/ohm/ - electronics general, the power fights you edition

[Anonymous No.1627131]

all tied up thread: >>1621755

>RULES
0. Electrics ≠ electronics. Appliances/mains stuff to /qtddtot/ or /sqt/. PC assembly to >>>/g/.
1. Do your own homework. Search web first. Re-read all documentation/datasheets related to your components/circuits. THEN ask.
2. Pics > 1000 words. Post relevant schematic/picture/sketch/9001.5 hours in MS Paint with all part numbers/values/etc. when asking for help. Focus/lighting counts.
3. Read posts fully. Solve more problems than you create.
4. /ohm/ is an anonymous, non-smoking general.

>I'm new to electronics, where to get started?
It is an art/science of applying principles to requirements. Find problem, learn principles, design and verify solution, build, test, post results, repeat

>Project ideas:
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Principles (by increasing skill level):
Mims III, Getting Started in Electronics
Platt, Make: Electronics
Geier, How to Diagnose & Fix Everything Electronic
Kybett & Boysen, All New Electronics Self-Teaching Guide
Scherz & Monk, Practical Electronics for Inventors
Horowitz and Hill, The Art of Electronics

>Design/verification tools:
LTSpice
falstad.com/circuit/circuitjs.html
NI Multisim
CircuitLab
iCircuit for Macs
KiCAD (pcb layout software, v5+ recommended)

>Components/equipment:
Mouser, Digi-Key, Arrow, Newark, LCSC (global)
RS Components (Europe)
eBay/AliExpress sellers, especially good for component assortments/sample kits (caveat emptor)
Local independent electronics distributors
ladyada.net/library/procure/hobbyist.html

>Related YouTube channels:
mjlorton
jkgamm041
eevblog
EcProjects
greatscottlab
Photonvids
sdgelectronics
BigClive

>Li+/LiPo batteries
Read this exemplary resource first: https://www.robotshop.com/media/files/pdf/hyperion-g5-50c-3s-1100mah-lipo-battery-User-Guide.pdf
>I have junk, what do?
Take it to the recycler.

[Anonymous No.1627160]

Opening Ritual

[Anonymous No.1627168]

>>1627160

[Anonymous No.1627179]

yesssss
that piece of shit relay is finally working properly now
i had to add a coupler there since the cunt wouldn't work with 3v and i managed to burn the usb power traces, but thank god the vin pin traces were spared so i can still power it via the vin pin so all is gud
but shit man. this is way more pieces that i hoped for. if i want to make a bunch of these plugs for to turn my house devices into iot bois, it will take a shitload of work to put together so many components for so many plugs
thank god for wire wrapping tho, it is making connecting all those pins together a breeze

[Anonymous No.1627193]

>>1627179
>that safety cap

[Anonymous No.1627196]

so why is this capacitor making the output goofy as fuck rather than smoothing the inverter's output

[Anonymous No.1627199]

>>1627179
>shitload of work
and that's why prototype pcbs are awesome
for funsies, post original board to see how much less of this you would have had to put up with had you just hacked the fw

>>1627196
>he doesn't know about resonant circuits and damping yet

[Anonymous No.1627201]

>>1627199
I know of them but I wasn't sure if that was going to make an LC tank circuit or not

how then would you go about smoothing the output of an inverter without making an oscillator

[Anonymous No.1627210]

>>1627201
usually you just call it a win since power was transferred
you might want to think about regulating the output voltage before worrying too much about wave shape, since true sine wave inverters start to look a bit more like a power amplifier anyway

[Anonymous No.1627264]

so all else being equal, an increase in current means a decrease in voltage?

[Anonymous No.1627268]

>>1627264
in the context of constant power, yes. was that the context of interest to you?

[Anonymous No.1627273]

>>1627268
I can't honestly say. I'm playing with diode clippers.

I see when the breakdown voltage is reached, the diode begins to conduct and thus shunts the current away from Vout. That's also where the waveform of the triangle wave begins to distort.

I'm trying to develop intuition for this. The way I'm thinking of it now is that in order to drive that current through the diode it must "spend" some voltage to do so. So some of the output voltage is redirected towards making the diode conduct, thus depressing the output voltage and distorting the waveform in the process.

Granted, that "spending of voltage" might just be from the voltage required to make the diode conduct and not be an inherent relationship between current and voltage.

[Anonymous No.1627286]

>>1627273
>not be an inherent relationship between current and voltage.

[Anonymous No.1627429]

>>1627193
>safety cap
what do you mean?

>>1627199
There is no original board, this plug had originally just a humble mechanical switch which i replaces with a relay and all that other ic stuff

[Anonymous No.1627499]

>>1627179
>Touch
No

[Anonymous No.1627524]

>>1627499
yes.
it is nice and flat and saves me from having to make an extra hole for an ugly switch
also i hope you aren't on about some reliability meme, i use touch switches in many of my iot devices and i haven't had a single misfire ever

[Anonymous No.1627532]

>>1627524
>an ugly switch

not trying to argue, but how do you use that "non-ugly" touch thing if you don't make holes for the three wires, and how is an ordinary 20 cent pushbutton uglier than your touch sensor? Do you have a pic of a finished project that uses a touch sensor? And if >>1627179 is a finished project then maybe you should disregard this entire post.

[Anonymous No.1627541]

>>1627532
you don't actually touch touch buttons you touch the casing covering them
for example i can glue the red part under my table and then when i place my finger ON TOP of the table it activates it is really cool, it looks like you are pushing an invisible button or can draw dick with a sharpie there and have a dick button

[Anonymous No.1627547]

>>1627541
>i can glue the red part under my table and then when i place my finger ON TOP of the table it activates it is really cool, i

that is amazing, if I understand correctly. You put the sensor on one side of a solid, stiff board, and it detects your finger through the board. Do you have a link or part name, because I'd like to try that.

For example, if I want to have 5 of them, how close together can they be if they are on the other side of a 3/4" thick board?

[Anonymous No.1627554]

>>1627547
just search for touch buttons, they are used everywhere these days
in fact you can make one yourself with just a piece of foil wrap and a wire

[Anonymous No.1627561]

>>1627554
>in fact you can make one yourself with just a piece of foil wrap and a wire

do you have an answer to the other part, where I'd like to have five or more of them on the other side of a 3/4" board? Also, how would I detect the signal from a piece of foil wrap and a wire located 3/4" from my finger? I assume it's capacitive, but can a weak capacitor like that really be used very far from your finger?

[Anonymous No.1627580]

>>1627561
I think they measure the impedance from the plate to "ground", but I might be wrong and they measure the fluctuating mains-frequency electric field coupled from your body instead. In either case, your body is a pretty good antenna for coupling to your surroundings.

A cursory glance at a product page tells me they're good to 5mm or so, but I guess you could multiply that by the relative permittivity of the relevant material. Some plywoods show they might have a relative permittivity up to 8, but MDFs look to be only good to 1.2 or so. But this also is quite dependant on frequency. A screw screwed most of the way into the board from the other side would certainly help though.

[Anonymous No.1627587]

>>1627561
>>1627554
>>1627547
>>1627580
https://en.wikipedia.org/wiki/Capacitive_sensing
https://www.youtube.com/watch?v=mWR9Q_pTagw

[Anonymous No.1627602]

>>1627561
Be the first to make it work.

[Anonymous No.1627727]

>>1627429
safety capacitor across the primary/secondary. apparently, instead of using a proper certified Y cap they just put a greencap in there. kek

>>1627547
>they are on the other side of a 3/4" thick board?
they work much better with only a couple mm of veneer separating them from their finger. 1/r^2 you know

>>1627561
>fucking touch switches, how do they work
http://ww1.microchip.com/downloads/en/AppNotes/00001334B.pdf

>>1627602
>>>/pol/ tryhard

[Anonymous No.1627749]

>>1627727
>fucking touch switches, how do they work

excellent reference. so they are wonderful, but rather challenging.

[Anonymous No.1627842]

hi im a brainlet and have no idea what i am doing other than a few college digital design courses i took. what can i do with parts of my old mp3 pic related

[Anonymous No.1627844]

>>1627842
read OP
>I have junk, what do?
Take it to the recycler.

[Anonymous No.1627867]

how do I become the recycler

[Anonymous No.1627908]

>>1627867
just a recycler or The Recycler?

[Anonymous No.1627931]

Has anyone ever found anything easter egg-y in a datasheet or elsewhere unexpected?

[Anonymous No.1627933]

>>1627931
closest I found was in a computer book's index, where there was a fake entry in the index for "daemon" or "demon" or something on page 666 (which wasn't in the book)

[Anonymous No.1627955]

>>1627842
The lipo (and its protection board) looks good, the screen may be usable if you can desolder that flat flex and find a datasheet for it, and some of the components on the PCB might be worth salvaging depending on your skillset and such. The main IC might be reprogrammable, but I can't see it being worth doing. I suspect the IC shown there isn't the main IC but the flash memory IC, so arguably you could replace it with a higher capacity IC to modernise it, possibly install rockbox on it if supported.

>>1627931
What about that "write only memory" datasheet posted a while ago?

[Anonymous No.1628041]

>>1627955
I'll see your Signetics 25120 datasheet and raise you the Umac 606 phantasatron
http://www.tubecollectors.org/archives/606.pdf

[Anonymous No.1628049]

>>1628041
the rare National Semiconductor LM0901A1411090451C "Polish Operational Amplifier", which "may be substituted directly for paper weights and fish lures". includes characteristic graphs, mostly characteristic of the comparatively un-butthurt workplace culture of the 1970s
http://idea2ic.com/FUN_DOCUMENTS/PolishOpAmp.pdf

[Anonymous No.1628066]

Noob here, can I use relatively thick audio cable instead of dedicated 6 amp cable?

[Anonymous No.1628078]

>>1628066
For power or audio? Or some other signal? What voltage? Frequency?

[Anonymous No.1628082]

>>1628049
>If a short length of 300-ohm twin lead is not available, use two short lengths of 150-ohm twin-lead
http://steamer.mindfart.com/

[Anonymous No.1628085]

>>1628082
>If a short length of 150-ohm twin lead is not available, use two short lengths of 300-ohm twin-lead in parallel.
works

[Anonymous No.1628106]

>>1627727
>safety capacitor across the primary/secondary.
Not him, but why would you want to add a short between the two coils? With ac it acts as a short and would defeat a purpose of the transformer?

[Anonymous No.1628110]

>>1628066
yes it's all copper inside so it doesn't matter (unless you got it from chinks in which case its aluminum)
the only difference is that audio and data cables have shielding around them

[Anonymous No.1628121]

>>1628106
that cap is kept small to keep touch currents non-dangerous
anyway its main purpose is to keep the entire output section and cable from becoming an antenna. it could be grounded instead or in addition, and if there were a ground lead, almost certainly would be

[Anonymous No.1628124]

>>1628078
220v, 50hz. Going to power two 30-45w light-bulbs.
>>1628110
It's actually both, aluminum for one polarity and copper for another. Don't ask me about it.

[Anonymous No.1628126]

>>1628124
>aluminium
In audio cable? Sure it's not tinned copper?

[Anonymous No.1628128]

>>1628126
I'm not but it's felt like a different, less flexible metal when I bend the tips around pins.

[Anonymous No.1628133]

>>1628128
>less flexible
Pretty sure aluminium would be more flexible. It's very difficult to solder onto aluminium, so that should give it away.
Without knowing the distance between the conductors it's hard to tell whether it's safe to put 220VAC across them. Half an amp should be fine if you described it as thick wire, but knowing the conductor diameter/AWG number would be good too.

[Anonymous No.1628234]

>>1627931

https://www.oreillyauto.com/flux-capacitor

[Anonymous No.1628251]

>>1628234
Jaycar (aus/nz overpriced electronic components store) has one of these on its online catalog for $10,000 or so.

[Anonymous No.1628296]

>>1628234
The line at the end tells me some retard tried to buy it

[Anonymous No.1628338]

Is my train of thought correct?
For reasons, the pure battery voltage of my lipo can be connected to the board. A DCDC converter that shares the ground with the battery supplies the entire board.
I used a pnp mosfet to prevent short circuits by reverse voltage protection. If I were to connect the mosfets ground to the boards ground and I connected the pure battery voltage I would create a short, right?
Consequently, if I didn't connect the mosfets ground to the boards ground and I connected the pure battery voltage cables the right way. Would the OPamps noninverting gate be powered by the pure battery voltage. Because they share a ground at the battery's boost converter pcb.

[Anonymous No.1628340]

>>1628338
>I connected the pure battery voltage in reverse*** I would create a short, right?
fixed

[Anonymous No.1628344]

>>1628338

Just for fun, use "pure battery" and "battery" in a sentence, so I can get an idea what you mean by pure battery.

[Anonymous No.1628359]

>>1628344
I thought that would have been more confusing but I guess you are right

[Anonymous No.1628421]

Has anyone used the capsense lib for arduino and measure how much delay there is in the detection. I am hoping it is on the magnitude of 1ms but I think Ive read that it is more like 5ms.

[Anonymous No.1628423]

>>1628338
Well, theoretically, your "pure battery" ground is shared with your DC-DC boost ground, which is your circuit ground.

I don't see why you put a mosfet on the "pure battery" ground.

[Anonymous No.1628428]

>>1628421
try the arduino general?

[Anonymous No.1628441]

>>1628423
Well if the Gate of the mosfet was connected to the circuit ground and the cables leading from the battery to the circuit were falsely connected (Battery voltage directly connected to circuit ground) there would be a short circuit

The battery is supposed to be removeable for charging so you would have to reconnect those cables everytime you connect its DC-DC converter to the circuit via USB ports.

So to prevent a short circuit I used the p-channel mosfet and connected its gate to the battery ground
This reverse voltage protection is not included in your schematic because I didn't go too much into detail regarding that

[Anonymous No.1628442]

>>1628338
>reverse voltage protection
Jeri Ellsworth did a vlog on reverse-polarity protection. you should find it and watch it

[Anonymous No.1628457]

The guy who taught me how to solder used to work as a cellphone repair tech. He had this amazing white flux that allowed him to beautifully rework microscopic components by hand and with no mess. He wouldn't tell me the brand, citing his NDA. Said his shop bought it in bulk. He was willing to part with this 1/10th of a CC because he was such a good pal.

Does anyone have any clue what this stuff is? I haven't even used it because when it's gone it's gone.

[Anonymous No.1628458]

>>1628442
also, your reverse polarity protection isn't protecting the dc-dc converter which almost certainly will release its magic smoke. instead just use a large-ish resistor between the battery and the voltage detector input. the comp's bias current is too small to worry about (if you chose your comparator correctly) so a large resistor (100k) won't cause significant error. in fact, as a general principle, a diff-pair (such as used in op amp/comparator inputs) should see the same resistance on both inputs for best balance and minimum offset, so you should add this resistor anyway, equal to the effective resistance to your voltage source on the other input. in the case of a simple voltage divider it's just Ra||Rb
in case of reverse connection, your dc-dc and maybe some stuff on the load side of it will be destroyed (but, thanks to the resistors, exceeding the common-mode range on the opamp/comparator or exceeding the input current rating won't be the direct cause of catastrophe)
anyway chink boost modules use a fair to large amount of current even with no load so don't expect more than a fortnight of operation from full charge

[Anonymous No.1628461]

>>1628338
I failed to decipher both the painting and the prose.

[Anonymous No.1628468]

>>1628457
Probably this stuff
https://store.rossmanngroup.com/index.php/amtech-nc-559-v2-30-cc-16160.html

[Anonymous No.1628475]

>>1628442
>>1628458
good video
The DC-DC converter has a built in short circuit protection, I suppose. good tip though
but ultimately the p-channel mosfet would take care of it too

>>1628461
Let me try again with this slightly altered schematic.
here, the mosfet's gate is connected to ground. If the battery voltages were reversed like in this picture, the battery voltage would short out every component on the board and probably destroy the dc-dc converter aswell
so my question is if it's a good idea to not connect the mosfet gate to the circuit ground

[Anonymous No.1628478]

>>1628468
Thanks for the identification and store link, Anon. It's cheaper there than Amazon by several dollars. And Amazon is FULL of chink knockoff fluxes of every variety.

Just bought a 30cc syringe. If it's not the same I'm sure it's a damn sight better than the rosin-based poop I need to throw away.

[Anonymous No.1628499]

>>1628457
that's what flux should be expected to do tho
the YouTubers who work with leaded solders seem to like *genuine* Amtech RMA-223 and NC-559 fluxes (as opposed to the vaseline available on alibay). those who work with lead-free have some no-clean options which are not quite as easy to find in hobbyist quantities
I've been using SRA's TF5000 tacky no-clean flux with the occasional coat of SRA's 99-20 RMA liquid when dealing with age-oxidized component leads. both are supposed to be safe to leave on the board, but the solder wire I'm using produces heaps of white powdery residue and burn marks. as a matter of caution and workmanship I wash those assemblies where possible by shaking in isopropyl alcohol for a few minutes

>>1628475
load short-circuit ≠ line reverse-polarity. review the absolute maximum ratings for the converter IC and you will probably see that the input voltage must never go negative
>ultimately the p-channel mosfet would take care of it too
it does cost an order of magnitude more than a resistor and is better suited to power protection than signal protection where a plain resistor won't work
... so, instead consider using a very-low-Rds(on) PMOS in line with the battery so that it also protects the dc-dc from reverse-polarity faults (Pic related, red). the lower the Rds(on) the less load-related voltage drop you will see in your voltage measurement under normal conditions. the AO3401 is an excellent jellybean PMOS for low-voltage switching if you can work with SOT-23s

[Anonymous No.1628528]

>>1628499
Hmm if I did it that way like in your schematic then the 5V of the DC-DC converter would be on the comparators input and not the lipo battery voltage which would be around 4.2V - 3.4V
Thanks but I'm already using the NX2301P which has similar specs

[Anonymous No.1628533]

>>1628528
>5V of the DC-DC converter would be on the comparators input
the comparator's upper input is connected to the battery through the PMOS, same as before. I've just placed the boost input "after" it instead of "before" it, so to speak. note the X signifying a broken connection
the dc-dc converter is a boost converter, correct?
cool, the AO3401 was just a suggestion

[Anonymous No.1628535]

>prototype pcb got into production 2 days ago
>check the manufacturer's design rules again
>minimum distance from trace to ground plane is 8 mil
>have 6 mil on my board
is it already over? this is my first pcb and I don't know if I fucked up and wasted 40 bucks in the process

[Anonymous No.1628542]

>>1628533
>I've just placed the boost input "after" it instead of "before" it, so to speak.
I realized that now. Wouldn't that overshadow the 4.2V-3.7V from the battery though?

>the dc-dc converter is a boost converter, correct?
I think it is. Though it's hard to tell since the markings on the ICs are barely visible.

[Anonymous No.1628549]

>>1628535
My opinion is that you should tie that knot again.

[Anonymous No.1628569]

>>1628535
>$40
>for an 8 mil design rule
should have gone with JLC
anyway you're not screwed, but you might want to pick up some pen knife blades

>>1628542
>overshadow
not sure what you mean. the boost just takes buckets of current from the input and throws them to the output. the input voltage is undisturbed (assuming an ideal source). there will be a small perturbation due to change in current demand from the dc-dc and its load. you could (and should, for reasons mentioned before) put a resistor on that input, and maybe add a capacitor so that brief load transients won't cause the comparator to change state based on spikes

[Anonymous No.1628575]

>>1628569
Oh damn I failed to see that the input of the dc-dc converter was connected infront of the opamp's input.
But since my dc-dc converter and battery are one unit I would have to hack it apart sadly. Thanks for the info.

[Anonymous No.1628580]

>>1628569
for that money im getting 3 boards and the option to revise my board which I did before but its too late at this point
also i want to support local manufacturers
ill definetely try that

[Anonymous No.1628584]

>>1628535
you're fine unless some idiot fucks with your gerbers. i've ordered 4/4 trace/space from houses that list 6/6 minimum. it means you're more likely to get a bad board but that's not really a big deal when you get 3-5 per order.

[Anonymous No.1628617]

>>1628535
The usual cheapo china production houses do test for continuity through the tracks so you're probably fine for open circuits, may need to inspect closely for shorts.

[Anonymous No.1628678]

>>1628499
Thanks for the flux info.

>those who work with lead-free have some no-clean options which are not quite as easy to find in hobbyist quantities

Any idea what those are?

[Anonymous No.1628690]

>>1628678
I was thinking 100g pots, but it looks like they do 30g syringes now, you serious hobbyist you https://www.kester.com/products/product/rf741-rework-flux
iirc this is the flux you see in action on the jkgamm041 youtube channel

[Anonymous No.1628716]

>>1628678
Don't bother friend, I was a lead-free fanboy until I realised basically every product out there was tailored for use with 60/40. The "joint gets weaker if you mix solders" is a meme, and the fumes contain no lead, so you should go to 60/40. Or 67/33 or whatever the cool kids are using. It's cheaper too, since you're not basically buying pure tin.

[Anonymous No.1628727]

Im playing around with an ah3503 hall effect sensor. Its supply voltage is supposed to be 4.5-6V but Im powering it off of 3.3v and it seems to be working. Also in the diagram it does not have a resistor anywhere but I remember the sensor heating up before. I put a 1k resistor at the end of the circuit and realized it messed up the output. If I use an internal pullup do I have to have an external resistor.

[Anonymous No.1628729]

>>1628716
>basically every product out there
out where, alibay?
>The "joint gets weaker if you mix solders" is a meme
true
>pure tin
3% silver probably doesn't help the price
but really, it's only 100 more °F, git gud

>>1628727
/ohm/ RULE 2

[Anonymous No.1628731]

>>1628729
sorry, thought I attached the diagram

[Anonymous No.1628733]

>>1628731
The a1321 is a linear sensor just like the a3505 so the wiring should be the same. The right one makes it digital.

[Anonymous No.1628738]

>>1628729
>alibay
Yes. Even Rossman reflows motherboards with leaded solder paste, apparently.
>but really, it's only 100 more °F, git gud
Personally I don't find lead-free any more or less difficult to solder, with or without my T12 temperature controlled meme station. My change was solely motivated by the available accessories and their prices.

[Anonymous No.1628797]

How the fuck do I get into networks? I'm a ee grad but more focused on hardware and power systems, networks are deep wizzardry for me. I'm thinking about making some sort of mesh network for some sensors with uC and aliexpress radio modules but I do not have a single clue on where to start learning, I can barely configure my router. (I can code alright)

[Anonymous No.1628811]

>>1628690
Thanks fren.

>>1628716
67/33 is very close to eutectic, so I stick to that.

I only know of one lead-free solder that's eutectic. But irony of ironies, it's 0.15% antimony.

https://www.sparkfun.com/products/10243

( If anyone else sells this stuff I don't know who. )

[Anonymous No.1628813]

>>1628811
>But irony of ironies, it's 0.15% antimony
Is that toxic? I know there are some interesting low-melt soldering alloys out there with indium and/or gallium in them, and also I think some specially designed to not dissolve gold contacts/pads. There's a wikipedia page that lists a bunch of different solder alloys (possibly also listed with other alloy types like brasses and such) and also states whether they're eutectic, and I bet at least half the ones I mentioned have semi-common eutectic blends. If not the ordinary 99.3/0.7% RoHS blend.

[Anonymous No.1628815]

>>1628813
Antimony is a poison, yeh. I don't know how much vapor comes off solder containing it, but I do know that a glass of lemonade with 0.013% antimony will send you to the hospital.

Concentrations are much higher in some lead-free plumbing solders: typically 5%.

[Anonymous No.1628821]

>>1628815
Well if they use them for plumbing I imagine it's safer than lead.

[Anonymous No.1628823]

>>1628821
I have no faith in get-this-horrible-awful-evil-material-out-of-this-industry fads. There are plenty of examples of substitutes being worse in different ways.

[Anonymous No.1628827]

>>1628823
Like the production of lithium ion batteries for cars being more environmentally damaging than petrol cars' emissions over their entire lifetimes? I'd tend to agree.

[Anonymous No.1628836]

Anyone have that DIY (rookie) project ideas image? I believe there were hundred different ones to choose from

[Anonymous No.1628858]

>>1628836
you mean the 00...99 /ohm/ projects list?

[Anonymous No.1628872]

what happens if you connect 5v to one of these chink power sources that normally turn 220v into 5v?
(the live and neutral side is not connected to anything)
when using it to power say arduino, and i plug the arduino in via usb, the light on the power source turns on and i am scared that the transformer will fuck my computer up by power surging it or some shit

[Anonymous No.1628882]

Tried to post on /adv/, got sent here. So:
I'm a EE major and I want to work on projects related to my major. I'm most interested in the field of Radio Frequency and the lack of intresting projects is killing my motivation. Not only for this major, but the others I've jumped from (Computer Eng, Mechatronics). I don't want to work on something that's at least hardly ever done, I can bring myself to do any of the common projects I've seen online.

Maybe I've set expectations way too high on what my projects should be. I am a undergrad after all. So any help on pegging down my expectations or feed my inspiration with some great project ideas

[Anonymous No.1628885]

>>1628872
Do you also expect mains voltage on the other side?
See for yourself why the LED comes up.

[Anonymous No.1628888]

>>1628885
Ah, that makes sense, the Dick 1 blocks the current flow so all is gud.
It is a mystery to me through why wouldn't they put the led before the dick, so I wouldn't get a scary 220v power source led on

[Anonymous No.1628904]

>>1628888
Interesting auto correction you have there.

[Anonymous No.1628919]

>>1628858
yes

[Anonymous No.1628921]

>>1628836
pls make free energy device i'm tired of energy bills

[Anonymous No.1628929]

Nice, it's working flawlessly

[Anonymous No.1628940]

>>1628888
>literally no knowledge of basic flyback operation
>unironically using it on breadboard shit
I'm even more suprised by your lack of knowledge on what inductor is

[Anonymous No.1628944]

>>1628919
voilà

[Anonymous No.1628961]

>>1628944
cheers

[Anonymous No.1628996]

>>1628944
Rolling on 57

[Anonymous No.1628998]

>>1628811
>antimony

[Anonymous No.1629000]

>>1628797
Halp

[Anonymous No.1629005]

>>1628797
it's kind of a big department. if I were being even more cheeky than usual I would direct you to something like the US Postal Service's Domestic Mail Manual, but nah
same general idea though: assuming you have a wire over which one or more nodes can send datagrams, it's more or less just names, addresses, envelopes, messages, etc.
what sort of range were you looking for? what level of MCU? have you settled on any radio modules yet? I would suggest the nRF24L01+ modules for maximum ease of use and minimum protocol bullshit
what you will have then is a radio that can send and receive packets of up to 32 bytes at 500kbps on any of 125 channels, unicast or broadcast, with a user-assigned node identifier up to 5 bytes long
then you can define command codes according to the operations that interest you (identify, configure periodic report, set actuator, etc.)
>>1629000
chekd

>>1628882
a bit surprised you couldn't find anything actually interesting in mechatronics, with such a short, sharp feedback path for the designer. unfortunately, not everything that needs to be done is interesting, not even necessarily on the way to an interesting project. maybe you have to do some chores first like reading a few hundred-page datasheets to learn about some component or how to control some IC, or characterizing a component or building block you've not used before

>>1628944
anyone else think this list is due for a refresh?

[Anonymous No.1629012]

>>1628998
why isn't she holding the metal part?
fucking amateur

[Anonymous No.1629013]

>>1629005
>refresh?
Feel free to update.

[Anonymous No.1629016]

Does anybody know why you would ever want to do this?
>2x part count
>2x cost vs just using bjt for higher power
>doesn't do shit for Power diss
Is the benefit that it's tracking, for multiple supply voltages?

[Anonymous No.1629029]

>>1628882
hey homie I'm basically you atm but I'm losing motivation bc there's the blurred line between low-hanging projects which seem easy and a waste of precious time vs. so challenging I lose interest or feel I'm in over my head. v frustrating.

But what subjects are you taking atm? How much time have you spent on projects (and when did u start ee)?

I've been building lab/test equipment bc it not only suits my needs but is only as challenging as you want to make it. If a Lm317 based psu is boring, try lm723 -> op-amp + pass bjt -> bjt diff amp w/ output stages. I hope you see the endless possibilities and opportunities to learn

[Anonymous No.1629034]

>>1629016
audiofags probably

[Anonymous No.1629047]

>>1629016
probably made a lot of sense back in the days when MOS ICs required triple supplies, could still make some sense in the event you need two rails to be a certain voltage apart, without regard to the distance from ground. e.g. building headroom for a non-RRIO op amp treating an RR signal from the lower set of rails, or a bootstrapping supply for high-side n-type pass transistors

>>1629012
some people would rather smell the antimony braps than hide the pungent aroma under burning chicken

[Anonymous No.1629051]

>>1629005
The idea that my school was selling to me is that a Mechatronics student learns CS, EE, ME for the application of creating autos. I don't have much intrest in creating automation, and felt the circullium was setting people up on being masters of none.
>>1629029
>Building lab equipment
That sounds like something I'll be intrested in doing. Will look into it

[Anonymous No.1629055]

>>1629016
>multiple supply voltages?
No, clean output.
>>1629034
>audiofags
One example; decoupling of line- and load-regulation.

[Anonymous No.1629077]

>>1629051
there ya go! bootstrap your workbench, working toward what does seem interesting by way of the more specific tools needed for it
>masters of none
once you're past that steep part of the learning curve and have that basic, working understanding, you can always pick up the details later if you don't feel like deriving them yourself for the exercise, and/or you can deal more intelligently with component vendors and their engineering staffs
an interdisciplinary approach did nothing wrong, ever

[Anonymous No.1629130]

Can anyone give me a transistor circuit for a SR latch that would actually recreate this effect? I've tried it with a few of the NOR gates implemented on falstad (TTL, ECL) and some simple other simple SR circuits, but none of them oscillate. It works with their logic gates though. Is this just an artifact of the abstraction process (aka a bunch of bullshit)?

[Anonymous No.1629144]

>>1629130
real life ≠ vidya. you're seeing an artifact of your simulator's discrete-time paradigm. it's acting as a hidden delay element
with real components, you won't get any oscillation without adding phase shift and gain. the parasitic capacitances etc. in your design aren't enough, aren't predictable, and are more likely to drown out oscillation than sustain it

[Anonymous No.1629185]

>>1628885
>implying any commercial converters won't just have a dedicated controller instead of a zener diode
You're probably right that the secondary side will be similar though.

>>1629130
please look into more rigorous oscillator topologies

[Anonymous No.1629212]

>Feel like I've finally learned enough about electronics to make my own analog design
>Start working on a simple VCO
>Realize that my design has a flaw when I start implementing it, turning my VCO into a horrible VCA
>That's ok, I'll just make a few changes here real quick
>Realize that my design has just turned into a shittier version of the venerable 555 timer.

WHELP, I guess I'll try again.
Either that or see if I can make some small improvement on the 555 to make it more like the VCO I was trying to make originally.

[Anonymous No.1629223]

>>1629144
I'm not following. You're saying the simulator is not mirroring real life but then saying that you don't get oscillations in real life... but that's what I'm getting in the simulator. And is that circuit you posted supposed to be what I asked for? I don't understand where the inputs are.

Pic is one of the circuits I tried that doesn't oscillate. Just copied and pasted the NOR gate example from falstad, don't actually know how they work, but it operates as an SR latch just fine, and when both inputs go from high to low the outputs stay low, no oscillation or unpredictability.

[Anonymous No.1629229]

>>1629185
I'm not actually trying to make an oscillator. I just want to know if digital logic is a lie.

[Anonymous No.1629234]

>>1629229
Well technically you could make an oscillator based around propagation delays, but I think it would tend towards a steady state unless you used schmitt-trigger gates (i.e. 74HC14 instead of 74HC04), and the propagation delays aren't very reliable.

>>1629212
Are you using JFETs or transconductance amplifiers? Because you should be. Relying on RC circuits is pleb circuitmongering. Capacitors + current sources/sinks is more acceptable.

[Anonymous No.1629243]

>>1629234
Cap + Sinking Current Mirror.
I've worked with transconductance amps before, but for this design I'd like to do the whole thing at the transistor level, as a personal challenge.

I haven't quite learned how a transconductance amp works at the transistor level yet.

[Anonymous No.1629246]

>>1629185
these days, sure. it's only in the past 5-10 years that controller ICs for switchers have gotten cheap enough to replace self-resonant transistor switchers

>>1629223
your logic sim is lying to you because it forces your design into a synchronous mode in order to simulate it. in essence, that turns your R-S into a J-K with a hidden clock of period 1 turn. your circuit sim is telling you the truth because oscillators like that don't happen irl
a more rigorous logic sim might be annotated with real min/typ/max delays, e.g. Verilog timing annotation
>posted
yes, there are no inputs. you can add another pair of npns across the b-e junctions (with obligatory base resistors) to hold the astable multivibrator in one or the other state

>>1629229
it's a lie, in the sense that all electronics is analog. the branch we call digital just happens to have looser standards on linearity and precision, being only specified at their extremes of input voltage, and as a rule have no ungated feedback path and run open loop (but the CD4069 inverter has been used as an oscillator and an analog building block with feedback more than once, and the CD4066 is famous)

>>1629243
prepare to be demystified
http://www.ti.com/lit/an/sboa117a/sboa117a.pdf

[Anonymous No.1629255]

>>1629243
Mind posting your circuit diagram? I'm interested in how you're minimising leakage in your capacitor circuit if nothing else.

[Anonymous No.1629260]

>>1627131
>replace batteries on a ups
>*a few minutes later*
>electrical arching and burning electronics smell
>*panic and cursing omitted*
>dissection reveals burnt looking goo from su'scon capacitors

Welp, I need a new UPS. Does anyone know off the top of their heads of any cheap-ish models that use good/Japanese caps (Rubicon, Chemi-con, Nichicon, Panasonic)?

[Anonymous No.1629285]

>>1629255
Sure, here it is.
I'm still early in the re-design, hence the schmitt trigger and op-amp, rather than discrete transistors.
I'm not really doing anything to minimize the leakage, this is a really simple design.

[Anonymous No.1629288]

>>1629285
Well using a 10µF cap does proof against leakages for the most part, but I'm concerned about the charge being dumped whenever you short it. More concerning is the arrangement surrounding that 4th NPN, surely a significant amount of current from the cap is being lost through that B-E junction?

[Anonymous No.1629298]

>>1629288
Yeah, I need to calculate what the short circuit current is.
Earlier I had a current limiting resistor, I just haven't put it back in yet.

>More concerning is the arrangement surrounding that 4th NPN
The emitter follower?
Input resistance should be about ~1MΩ, since Rin = beta*Re = 100*10,000.
It doesn't draw any appreciable current in the simulator, although I do admit that it is rather useless at this point, since the ideal op-amp and schmitt trigger both draw zero current.

[Anonymous No.1629302]

>>1629298
Oh that's reasonable I guess.
I'm guessing that you adjust the resistance of that 1k to change frequency?

[Anonymous No.1629308]

>>1629302
I change the voltage going into the 1k to set the frequency, basically a dead simple voltage to current converter.
I'll need to calculate the proper resistor and capacitor values though so I'll have an actual known voltage to frequency relation.
Right now I just have 1k and 10uf because it works and I can test the control circuitry with it as such.

[Anonymous No.1629312]

>>1629308
>Right now I just have 1k and 10uf because it works and I can test the control circuitry with it as such
Yes it's definitely easier when you know what to expect. Certainly better than dealing with those time constants from Rc circuits in any case.
I'd be interested to see what happens when you go from a 10µ to a 100n or so; whether you start to see nonlinearities in the charge curve.

[Anonymous No.1629315]

>>1629312
Me too, although I feel like that might be a better test for when I actually implement it with real transistors.
Simulators are nice, but this one doesn't even model things like leakage current as far as I can tell.

[Anonymous No.1629316]

>>1629315
>this one doesn't even model things like leakage current as far as I can tell
How about swapping to a free spice instead?

[Anonymous No.1629320]

>>1629316
I need to learn how to use spice.
At college we were taught how to use PLECs.

I do have LTSpice installed on my computer, but I need to RTFM.

[Anonymous No.1629332]

>>1629320
Is it a mac? Because if so you'll have to do everything with hotkeys or the right-click menu because they decided that a toolbar was too difficult to code.
All you really need to know for basic operation is:
>ensure you have a ground node somewhere on your circuit
>all basic parts must have a value
>part values can be written with standard notation like 4.3u, 10meg, 5m3, etc. (meg = 10^6, M = m = 10^-3, because they aren't case sensitive)
>all transistors and such should have a model name selected (diodes don't really matter as much as transistors)
>use ".tran 0 50m" to simulate for 50ms
>use "Pulse" voltage sources in order to have voltage sweeps (i.e. from 3V to 5V)
>feel free to change the names of components from "C2" to "charge_cap" or whatever you fancy
>

[Anonymous No.1629342]

>>1629332
Ah, thanks.
I am using an old mac. I though the interface seemed oddly barebones.

[Anonymous No.1629394]

I'm a total noob, is it possible to control a 40W RGB LED panel with arduino? It comes with a remote but I can't use it for what I wanna do (automatic f.lux-like behaviour)

[Anonymous No.1629397]

>>1629394
Definitely possible. How many wires are going from the receiver to the LED panel? If it's only 4 then it's an easy task, requiring only PSU hardware, 3 correctly rated MOSFETs, and possibly a few passives.

Also check whether the default controller is constant voltage or constant current, because if it's the latter you may run into some issues with PWMing it and may want to current-dim it instead if the power supply allows for it.

[Anonymous No.1629399]

>>1629394
>RGB
I don't think you're going to be very happy with the quality of light out of that. you are still going to have blue wavelengths in the light unless it's pure yellow. consider getting a warm white+cool white panel (or build one from convenient components on ali)

[Anonymous No.1629400]

>>1629399
It's not that bad, I just stick to colours without any blue in them. Mainly yellows and oranges. The poor colour rendition is certainly noticeable, but not annoying. Ideally I'd have 6000K-2000K dimmable white, possibly with 500-1500K or red also, but 2000Ks and colder are rare.

[Anonymous No.1629421]

>>1629397
I don't have the panel yet, but in this video I can see 6 wires https://youtu.be/2Dom80vEEas?t=29

>>1629399
I know that the quality sucks, but the "warm white" is usually not less than 2700K, which is still too cold for me after 9pm

>>1629400
What's your setup like?

[Anonymous No.1629430]

>>1629421
>6 wires
>RGBWW
That will be either 1 common cathode and an anode for each colour channel, or 1 common anode and a cathode for each colour channel. Since it has V+ in the video, the 5 channels will be controllable with N-channel MOSFETs. Someone else may suggest good FETs, otherwise I'd just search for a common voltage range (35V?) on ali or wherever and make sure it can handle the current. Should be easy enough to drive. I'd also grab a buck converter with which to power your arduino (assuming it won't be connected to a running computer all the time). I don't think you'll need gate resistors for the FETs.
Do you have a purchase link?

>What's your setup like?
Pitifully weak 5V 1.8A USB LED strip draped over my oscilloscope. It's the model with the RF remote+receiver, which occasionally is triggered by something other than my remote, which is a pain. The red is also way too weak, so the yellow looks like a lime and the orange looks like a yellow, and the remote just has those presets so I can't go any more orange.
But I'm slowly working on a more powerful RGB setup with a driverless RGB COB, which may or may not be unusable thanks to the 100Hz flicker. The external driving circuitry required is also stupidly complex, so I don't recommend purchasing one. But it will have nice adjustment knobs and an on-off remote, neons on the front, and a stylish laser-cut acrylic case. I'd be working on it now if the maker space wasn't closed for a few weeks and I didn't have an exam in 9 hours.

[Anonymous No.1629432]

>>1629077
>bootstrap your workbench
Is this a reasonable goal? Do people often use DIY equipment instead of buying their instruments in EE? Not him, but I don't want to get my hopes up.

[Anonymous No.1629461]

>>1629430
Thanks for the advice. This is the panel i was looking at: https://www.ledpanelwholesale.co.uk/led-panel-60-60-rgbww

>Pitifully weak 5V 1.8A USB LED strip draped over my oscilloscope
what do you use it for, is it just for decoration? And what are you gonna do with the COB, isn't that stuff used in live performances?

[Anonymous No.1629464]

>>1629432
People often make their own PSUs since they can use standard ICs or even pre-built modules. ±0.1V accuracy is pretty easy to obtain with an MCU ADC. Making one with a rotary switch or two and an old multi-multi-tap transformer (e.g. from a tube tester) is also somewhat popular. Simple function generators are also somewhat easy to make with a microcontroller driving a display of some kind with a rotary encoder and a few buttons. Scopes and more advanced function generators are less likely to be plausible to make, if only because of the fine temporal resolution required.
RCL meters are a neat project as long as they're not dealing with mΩ, nH, pF, etc. There are various degrees of depth you can go when characterising an inductor (ESR, parallel capacitance, core effects) but that's really just a DSP/software problem. Your accuracy comes down to what tolerance parts you use

>>1629461
Both used for lighting my bedroom.
>65 eurobux
That's a bit pricy. I wonder if replacement LCD backlights can put out enough power to be used?

[Anonymous No.1629472]

>>1629464
>replacement LCD backlights
Scratch that, they don't come as panels, just as the edge-lighting LED strips. You'd need a translucent panel to shine them through, which arguably isn't a difficult task. A piece of acrylic plastic sanded on one side with foil on the other and LED strips around the perimeter would do a decent job for under half the price.

[Anonymous No.1629521]

>>1629464
>That's a bit pricy
I can't find anything cheaper that delivers in EU

[Anonymous No.1629577]

>>1628929
Finally finished.
A fancy smart plug which i can easily turn on or off from anywhere in the world through my own api.
It was really easy to hook it up to my google assistant too so i can say shit like "hey google turn the fan on" and in couple of seconds it clicks (and i obviously plugged the desk fan into it)
I am very happy with the result
And its size is not that much bigger than commercial plugs.

[Anonymous No.1629608]

I'm looking at buying a red pitaya as a general electronics fuck around device. I want something cheap and compact with a lot of features because I'm an apartment bitch and I don't have any space.
Any better ideas? EEVBlog shat on the device 3 years ago and the default web interface looks fucking terrible so I'm skeptical about it.

[Anonymous No.1629617]

>>1629577
Good work!
Now I understand why type F plugs have this weird hole.

[Anonymous No.1629686]

>>1629617
>weird hole.
what hole? you mean the ground pin?

[Anonymous No.1629691]

>>1629472
>I have junk
20W (nominal) light engines can be gotten for like a buck each on ali, in your chioce of color or white

[Anonymous No.1629720]

>>1629686
Yes, (PE) pin in the socket, hole in the plug.

[Anonymous No.1629727]

>>1629691
>20W light engines
Not getting any concrete results from that search.
I think I'd prefer LED strips since they don't require a heat sink and have a good variety of styles and colours, but I am somewhat open to suggestion.

[Anonymous No.1629767]

>>1629727
there exist light strips with warm (like 3200K?) and cold LEDs, in the standard 4-pin configuration. if you wanted to you could augment with some monocolor strips in red, orange, and yellow
for engines you could try "hong li cob" and see what you find. you might be able to get away with simply thermal-gluing them to a metal sheet or plate if you're not pushing them to horticultural power levels

[Anonymous No.1629863]

>>1629767
You can also get strips with RGB+warm+cold white all together.

For my desk lighting I use a strip of the WS2812 clones with RGB+warm white, it's pretty nice, the white is pretty warm, somewhere around 3000K, and full white + full blue can get it to a real bright ~6500K

[Anonymous No.1629876]

>>1629767
>hong li cob
Woah those are cheap. What are they used for?
The same seller also sells ~130V and ~180V models, which look to be for fairly simple step-down converters running off rectified mains. Which could make a fun project, making a variable current-limited mains buck converter.
>4-pin
Don't you mean 3 pin? I found a couple of sellers selling single-color 2000K or 2500K LED strips, in particular this one:
https://www.aliexpress.com/item/strip/32858633850.html
Which I might go for, but they will require a power supply of some sort. And considering the power selection is "14W" and nothing else, regardless of how many metres, and there aren't any images of the strip face itself, it's hard to know what to go for. The description page says "14W/m" and "cut size 5cm", but also "120LEDs per metre" and "120 light beads per m" on two seperate occasions, with lengths of 1-5m. So I guess I'll want a power supply in the realm of 24V 3A and some sort of dimming circuit, since I can't seem to find any appropriate constant-current-dimming power supplies. Multiplied by two, since I'd want the 6500K and the 2000K.

>>1629863
I don't exactly need

[Anonymous No.1629893]

>>1629876
light fixtures, etc.
>3-pin
4. they use the same tape as the RGB strips but mount W+CW LEDs on them. one of the pins is unused
https://www.aliexpress.com/item/High-quality-24V-benis/32450008748.html
>cut size
is probably the distance between cut lines and the size of each parallel cell. at 120LEDs/m there are 6 per cell, which makes sense for a 24V strip
>constant-current
I have yet to see a strip designed for constant-current. they tend to be designed for constant-voltage for ease of use (e.g. parallel connections, trimming to fit, no need for a CC driver). just add a few kHz of PWM switch and enjoy

[Anonymous No.1629895]

>>1629893
>at 120LEDs/m there are 6 per cell, which makes sense for a 24V strip
Oh that's actually a perfectly reasonable number of LEDs. I figured it was far too many, but with 6 per 5cm segment that's quite plausible.
>I have yet to see a strip designed for constant-current
It wasn't that the strip had to be designed for constant current at all, but rather that it would be easier to control its brightness by varying the current than by varying the voltage, thanks to the Shockley diode equation. I'm unsure of what happens in this middle-ground between PTC and NTC characteristics, but would a strip with both PTC resistors and NTC LEDs be able to handle CC and CV operation without thermal runaway? You're already dropping 3/4 of the voltage across the LEDs but they run just fine on CV supplies.

I also wonder about the COBs with no apparent current limiting/PTC features. Are they meant to have some sort of CC power supply? What about the automotive ones? The battery voltage fluctuates far too much to imagine them working with LEDs.

[Anonymous No.1629981]

>>1629876
>variable current-limited mains buck converter.
could be exciting, take that as you will
an isolated converter would be a bit of trouble to put together (this is about 7 projects down my get-to list) but a buck would be ezpz once you've found the right converter IC (the HV9910 is a good choice, bring your own high-voltage MOSFET to reach current levels that shouldn't even be possible)

>>1629895
>had to be designed
doesn't have to be, but (for efficiency) it does help
>PTC resistors
sounds dicey, not least due to thermal matching, PTC dissipation and how bou dat inrush current on cold start
>no current limiting
COBs do generally depend on a CC driver
>automotive
they probably just run them over spec like low-tier household LED lamps. B+ has maybe 2.5V of uncertainty, depending on how shot your battery is
that said, there are two-terminal current regulators in SOD packages, from ON Semi and others, that can simply be placed in series with an LED string connected to a voltage source with a little bit of headroom (too lazy to look up right now)

[Anonymous No.1629983]

>>1629981
>the right converter IC
I was considering going for a shitty comparator-based bang-bang circuit, but they're not too good when you want them to be adjustable as they kinda need tuning for the frequency, duty-cycle, output voltage, etc. Are there not flyback ICs with provisions for a variable output? Or is it the transformer with feedback windings that you're battling with?

>>PTC resistors
I was just meaning normal carbon-film resistors. They have a slight positive temperature coefficient that prevents the LEDs from going into thermal runaway. Though perhaps this would happen anyway with a constant resistance.

>two-terminal current regulators
Apparently you can just use a JFET as a constant-current diode. Not that I think they did that, it's probably closer to an LM317 with the sense resistance chosen to give the desired current.

[Anonymous No.1629984]

>>1629876
see also https://www.aliexpress.com/item/SZYOUMY-24-Key-IR-Remote-Dimmer-DC12-24V-Dual-White-CCT-Color-Temperature-Controller-With-FOR/32879494805.html which you can augment with transistors of your choice so you can PWM an entire block of flats

[Anonymous No.1629990]

>>1629984
I don't like quantised color choices, I'd prefer a custom remote with knobs on it. Custom because they don't exist. 256 different PWM values would likely suffice, though I may want to split them up logarithmically. Ideally I'd add inertia to the rotary encoders to get fine and coarse resolution depending on the speed at which I turn them, but I could also use the push-in-centre encoders with the button=not in telling it to count more quickly.

[Anonymous No.1630009]

>>1629983
you could probably make a hysteretic approach work, if you're willing to accept a fairly high minimum output current
some flyback ICs use a bang-bang approach, using a transistor optocoupler and a TL431 or similar to pass a voltage-too-high signal across the isolation barrier. if driving a high current, you might need some extra circuitry on the secondary side to amplify the current sense resistor, in order to keep its dissipation low (monolithic drivers use reference voltages on the order of 200mV), or you use a feedback winding
sadly, switching power supply transformers are, for the most part, not off-the-shelf parts
>slight positive TC
look up the curves and see if they match
>Not that I think they did that
looks like not much more than a self-biased transistor. Pic related

>>1629990
>knobs
>porn music starts
capacitive touch sliders?
>porn music intensifies
if size doesn't matter
>porn music has escalated
you could go all out and get some high-end rotary encoders like the chinky $12 ones (cheaper than $46 compact multi-turn panel pots). put some modern weighted metal knobs on there and there's your inertia
>split them up logarithmically
2.0 gamma is computationally easy: just square the requested intensity. it's not precise but it's better than not. if you have a bit more than 8 bits on your PWM, you're set
might be fun to learn your way around the special features of the STM32 timers, like the quadrature decoders, DMA for making remote control protocol bits, etc.

[Anonymous No.1630016]

>>1630009
Op-amps on the secondary to amplify and schmitt trigger the signal (with low hysteresis), feeding an opto that feeds the oscillator enable? With step-down converters it might be easier to have a significant amount of your peripheral circuitry on the secondary, at least considering the required low-power linear dropper needed to feed the active components.

>you could go all out and get some high-end rotary encoders
>weighted knobs
Size would be the biggest constraint. Ideally I'd go for some thin multipole magnetic discs in laser-cut acrylic with a bushing or two and a hall sensor nearby for a 3mm-thick encoder, but that's likely a dream. I saw some of the single-dimmer remotes (either warm/cool or light/dark) have something like a capacitive dial, but I wouldn't trust its resolution.
As far as weighted knobs, I'd prefer the software inertia to such a clunky hardware implementation. The transmitting micro could fairly simply measure the direction and frequency of the turns, and square the frequency, before sending over data in the form of [bool=encoder, bool=direction, int=number-of-steps] every 10ms or so. Probably via RF, since the PWMing lights could interfere with the IR operation.
A standard arduino has only 8 bits of resolution in its analogwrite function, but I'd likely be able to custom bit-bang that up to at least 10 bits at a reasonable frequency. With some sort of non-volatile memory to store brightnesses between powerdowns.

[Anonymous No.1630018]

Inductor are more complex than I thought

[Anonymous No.1630019]

>>1630018
that PWM waveform had better not be the sine output of your function generator

[Anonymous No.1630022]

>>1630019
Hysteresis current control

[Anonymous No.1630040]

>>1630022
Well regardless it's those high-frequency components that will be going straight through that low-freq ferrite.

[Anonymous No.1630048]

>>1630040
Yes, it's all about core material

[Anonymous No.1630125]

>>1629983
>Are there not flyback ICs with provisions for a variable output?
There are, Innoswitch3 comes to mind (other manufacturers should have equivalent as well)

For cheapass version I had some success with simple flyback converters with optocoupler control where you design transformer for maximum output power and via optocouler on-time bring voltage down.

Fastest way is to use dc/dc converters after flyback

[Anonymous No.1630131]

>>1629608
>125MS/s
Does it have a single-channel mode where it can do more than that? Because that's pretty low otherwise.

[Anonymous No.1630136]

>>1630125
>Fastest way is to use dc/dc converters after flyback
Yeah I'm getting that feeling.
Is it even possible to use a feedback winding to provide current feedback?

[Anonymous No.1630146]

Hey /ohm/, got these LED strings from a friend who wanted to throw them out because the battery compartment broke, so I intended to just wire them to a new one.

But looking at them, this is just exposed copper wire running electricity through them. I have very little understanding in actual electronics - how do people not get electrocuted touching them when they're plugged in, closing a circuit with their finger by touching both wires? Is there a resistor of some kind near the batteries to lower the voltage significantly? Am I endangering myself by just connecting them to a live AA battery?

[Anonymous No.1630148]

>>1630146
Also I realize I sound dumb and ignorant, because I am, which is why I'm asking.

[Anonymous No.1630149]

>>1630136
partially
As load increases on secondary, feedback winding will also generate higher voltage
After than I have no idea if it's possible to get accurate estimations on actual current going through (especially with variable output voltage)

[Anonymous No.1630156]

>>1630149
How about a shitty parallel ADC feeding an array of optocouplers, which feed an R2R ladder "DAC"? Ideally your ADC would be passive like the R2R, but I'm unsure how you'd get that to work without some sort of array of comparators and reference voltages.
Doing it serial would also be an option I guess. Just have an MCU on both sides of the circuit, use one for the ADC to measure the current, and the other to receive the data and modulate the frequency and duty-cycle as it sees fit. That wouldn't be a terribly difficult circuit either, though a not terribly efficient one as far as power consumption and BOM cost goes. But I would like to be able to tweak the CC and CV characteristics and modulation methods purely via software. It would be dead easy to interface with a digital remote also.

[Anonymous No.1630163]

>>1630156
Actually, just having the main controller MCU on the secondary side that directly pulses the main FET with the optocoupler could work, provided you get your bootstrap MCU power supply right and optocouplers could be made to fire fast enough. Like pic related but probably with a totem-pole between the opto+pulldown and the main FET.

[Anonymous No.1630178]

>>1630156
>How about a shitty parallel ADC feeding an array
Needlessly complicated

>>1630163 example would be preferred way
But generally I would still prefer DC/DC on secondary side, especially with CV/CC, currents sensing and other requirements.

If you insist on having control over mains switching - I suggest reading ST AN4930 for reference

[Anonymous No.1630180]

>>1630178
I just figure control over mains switching would be more energy efficient and less noisy, and would also be a neat project for project's sake. The sort of thing I might modify into a variable benchtop power supply with the help of a linear regulator of some kind for ripple rejection.
Though perhaps feedback via an MCU would be too slow for a case with a highly dynamic load.

You're certainly right that stacking two converters would be ideal as far as cost and simplicity goes.

[Anonymous No.1630193]

>>1630146
I will give you a fast answer.
First, the copper is very likely to be coated with resin or plastic. So it wont conduct or short circuit when tangled.

Second, if it's a small light battery powered, you have no chance of being electrocuted. Your skin protects you against electricity in the following way :
Shortly put, DC burns, AC contracts your muscles against your will.

At low voltages (<24-50V) Voltage is too weak to go though your skin.
At low current (depending on voltage, <10mA for AC, 2A for DC 3-4W I guess?), even if the electricity flows through you, you dissipate the heat, and "everything is fine" (see capacitive touch).

If there is enough voltage, it will go through your skin and will "command" your muscle against your will". Funny to move your legs to exercise, lethal if the current decide to control your heart.
If there is enough current, an arc can form and burn you flesh (don't look picture of electrical burn by the way. Unless you don't want to sleep that night).
If both, you are screwed even before touching the wire.

An electric car is battery powered, and is fucking dangerous (battery wise) because of high voltage and current, even if DC.
Your house live is dangerous because it's high voltage AC.
Your car battery (to start your thermic engine) is mostly not dangerous because it's low voltage. Don't touch it with wet hand tho, it have lot of current and can burn (as in destroy) your hand.
Your cell phone battery can still burn you. But it have a protection circuit witch will prevent it.
An AA battery is tottaly safe (electricity wise. I'm not responsible if you shove it elsewhere).

A funcky urban says (legend or not, I don't know) is that you can die if you touch a 9V battery with your tong.
It's a really particular case of your tong being wet and full of nervous terminals and close to the brain, and a voltage that is sufficient to pierce your skin in these conditions. that seem plausible to me, but I have nothing to back it up.

[Anonymous No.1630210]

Im new, and I want to surface mount LEDs for flashlights onto MCPCBs.
Ive looked up surface mount soldering, but from what im reading bare LEDS are really really frail and finicky with heat. They have domes on top of the LED that can get fucked up with heat too.

Pic related is someone elses picture of the MCPCB I want to swap an LED on, its from a particular flashlight.

What would be a safe way to do it, that isnt prohibitively expensive.

[Anonymous No.1630241]

>>1630210
Do it by hand if you know how to solder :
Apply flux to PCB and LED.
Put solder on one AND ONLY ONE PCB's pad.
While gently massaging your solder with your iron to keep it fluid but not to hot, place the LED with tweezers.
If you can't have it placed correctly in less than two second, remove it, wait a bit and repeat.
As soon as the LED is placed, you want to remove your iron while maintaining your LED in place.
Inspect your one leg soldered LED and maybe try it.
If everything is fine and well aligned, just solder the remaining legs, one at a time leaving pause in-between.

Do it with a hot air gun if you are crazy :
Apply flux on both LED and PCB
Apply solder paste on the PCB
If needed, apply glue to the LED
Put in place the LED onto the PCB
GENTLY blow your hot air gun drawing circles atop of your PCB. (remember to fix your PCB with klapton tape or any other method of it not to fly.
You can use tweezers if the airflow is too heavy to maintain the LED.

Do it with a plancha if you already have on and know how to do it :
Apply flux on both LED and PCB
Apply solder paste on the PCB
If needed, apply glue to the LED
Put in place the LED onto the PCB
Turn on the plancha and wait for it to get hot.
Turn it off when the solder starts to meld, with thermal inertia, it will be ok.

In any cases, solder more than needed.
The newer to solder, the more you want to solder (or try to solder).
Like, buy a bag of 5 PCB and 5 LED if you ned 1.
Good luck, and learn well.

[Anonymous No.1630242]

>>1630148
>dumb and ignorant..
>>1630193
>you can die..
From Make-Electronics (free excerpt)
Motto: "... I want you to burn things out and mess things up, because this is how you learn the limits of components and materials."

[Anonymous No.1630285]

>>1630242
As soon as you burn components, I'm more than okay with your motto.
But hurting itself for life is not a good idea.
Shock yourself as much as you want, it's a good way to learn. But shock you on areas that are non lethal and with currents and voltages that wont leave permanent damages on yourself.
I shock myself with a 320V fully charged capacitor 100µF (flash lamp one) and an other time a 4000V 100nF across the heart, and I can tell you, it's very unpleasant, and I have to sit for 5 minutes to feel "okay, I can resume my task now".
If I were to be unlucky this very same day, I would just have died.
So, shock yourself on hands, or legs (circuits do happens to fall from the bench sometime).
But don't shock you near head or across heart.

By the way, if you shock yourself, remember to drink water afterwards. The current ionize your cells, and you have to fill them up.

[Anonymous No.1630327]

Searching for milifarad caps on ali is so annoids, all listings come out a microfards since mf and mf

[Anonymous No.1630328]

This must be a scam right? no way they sell 40f cap for $1.5
https://www.aliexpress.com/item/2PCS-super-scam-benis-capacitor-farad-capacitor-2-7V-2F-3-3F-4F-4-7F-5F-6F-7F/33014262131.html

[Anonymous No.1630351]

>>1630156
optocouplers are analog (current transfer ratio is an important figure of merit) and monotonic, just not necessarily very linear. only one is required

>>1630210
bottom heat (hot plate, air, free choice) AND soldering iron

>>1630178
>Needlessly complicated
it's that one guy's trademark

[Anonymous No.1630356]

>>1630328
weirdly, LCSC doesn't appear to offer supercapacitors and ultracapacitors. no benchmark to be had there. I still don't see that price as completely out-of-sorts (for a 2.7V device)
order one. be the dave for us and test actual capacity. then open it up and show us the gigantic MLCC inside

[Anonymous No.1630447]

>>1630193
Firstly. this was a thorough, exhaustive, base-level explanation in lamen's terms that I did not expect to get. Whether it's instant paste from some digital text is irelevant, you have my thanks.

Secondly, I don't think the copper is coated at all. Sure, I won't plug it into a wall socket and close the terminals with my tongue, I just want to connect it to a couple batteries; but what about other things that touch it and might be moist - curtains, bedsheets, animal fur? If they conducted the current from the (possibly) exposed wires, would that be enough to start a fire or otherwise be dangerous?

Are simple batteries DC?

There's some component in the battery box between the switch and the wires (pic related) - what could it be, and is it needed? (I assumed it's a resistor)

Despite the recent /pol/ invastion, /diy/ is still the best board by far.

[Anonymous No.1630506]

>>1630447

you're the worst scaredy-cat i've ever read. low-voltage DC circuits (especially ones with little batteries) are completely safe to play with. you dont have to worry about shocks until you're in the 50+ volt range, and even then it's just a tickle. you can even short small batteries (AAA to D size) and they'll just get a bit hot.

>I don't think the copper is coated at all.

thats crazy talk. i guarantee it is. else everything would be shorted together and nothing would work. it probably uses a very thin enamel coating.

> (I assumed it's a resistor)

looks like a 5.1 ohm resistor to limit current.

[Anonymous No.1630512]

>>1630506
>you're the worst scaredy-cat i've ever read
Well, which do you prefer - someone too scared to connect a simple battery to an exposed wire, or someone hasty and arrogant they don't give a shit and kill themselves? regardless, I'll give it some current and see how it works. Thanks again.

[Anonymous No.1630525]

What would be the best way to do this while not taking up a lot of board space? There also isn't a lot of current involved, mainly for connecting to industrial sensors and the like.

[Anonymous No.1630539]

>>1630447
Thx m8.
No, it's not a pasta, so happy to help.

As for wires, >>1630506 is right, if it runs on batteries, not only it's completely safe, but it is obviously coated (just try to put new batteries and when everything lights up, put a paper clip between the wires for a short time. If light goes out, it was bare if not, LEDs will still light up.
You only have two wires here, so the only possible way is that LED are mounted in parallel (meaning each (+) connected together and each (-) connected together). Let's simplify and say that it will act as a single 'big' LED.

The law you are looking for here is Ohm's law : U=RI
or Voltage = Resistance * Current
It only works for DC (Direct Current, meaning "stable" current, as in batteries and most supply < 12V)
Lucky for you, I think the module works on 3 AAA batteries.
So DC current @ 3*1.5V = 4.5V
FYI batteries don't delivers 1.5V, but instead from like 1.7V when full to 1V when flat depending on chemistry. But here, we don't care, let's keep it simple.
So, U=4.5 V or is it?
Nope.
The LED will need some voltage to light up. It will depend on the kind of LED. Red are the oldest and lest demanding of visible LED and can need as low as 1.7V. Blue (or purple) the most demanding at 4.5V. Here, you have white ones, so we can take 3.6V as a wild guess.
So U = 4.5-3.6 = 0.9V

Okay, great, you spot the resistor, and a nice Anon tells you the value : 5.1 ohm
Green : 5, brown : 1, gold(when on the third ring) : *10^-1 gold(when on the fourth ring) : +-10%
so, the resistor is 51*10^-1 or 5.1 ohm +-10% JFYI

U = R * I
so U / R = I
So, here 0.9 (Volts) / 5.1 (ohm) = 0.176 (Amperes) = 176mA (milli Amperes)

Great. Now, count the LED, if you have 25 in your strip, each one will have 1/25 of the calculated current. So 7mA.
As most of the time these kind of LED can take up to 10-20mA, you are good.

If you want to improve your skills, do the math for a 5V supply (a USB port).

[Anonymous No.1630544]

>>1630525
A step-up converter of course.
https://www.ebay.com/itm/MT3608-DC-DC-Board-2A-Step-Up-Converter-2V-24V-To-5V-9V-12V-28V-Boost-Module/123540180282
Beware, it will very likely induce noise on your power rail.

>>1630539
Aaand I shat myself up, no spoiler on /diy...

[Anonymous No.1630547]

>>1630544
I think you're misunderstanding the issue.
I'm not trying to power anything just read the state of say a switch but it needs to be flexible enough to work with multiple voltages.

[Anonymous No.1630575]

>>1630547
Nigga, you talk about "5V, 12V and 24V I/O" and "industrial sensors".
Thing like presence sensor or other delivering a 24V signal (analog or digital) needs a 24V supply.

If you wanted to read any entry from any kind of voltage, you should have say so directly.

If you just want to read a switch, why in hell do you want to use it with 24V?

If it's some kind of presence sensor, most of the time you can choose an open collector style, so don't care about the voltage.

If really you need to swap sensors using different voltage, use a phototransistor and a diode in the sensor side.
This way, no matter your sensor, you have something isolated.

[Anonymous No.1630622]

>>1630193
> A funcky urban says (legend or not, I don't know) is that you can die if you touch a 9V battery with your tong.
If that was true, I'd have been dead by the age of five. 9V is enough that you can actually feel the current when applied to the tongue (but not to dry skin; you need around 50V for that).

>>1630447
> Secondly, I don't think the copper is coated at all.
It's coated. Copper wire used as an electrical conductor always has some form of insulation. Copper "cable" (single-core or stranded) is surrounded by a tube of plastic, "bare" copper wire (used for inductors, transformers, solenoids, etc where you need many turns) is enamelled.

[Anonymous No.1630626]

>>1630193
>he doesnt check to see if a 9v battery is still good with his tongue

[Anonymous No.1630629]

>>1630626
do you kiss your no gf with that mouth?

[Anonymous No.1630668]

>>1628457
>>1628478
>>1628499
Hey anons, I just got my Amtec goo today. It's not the secret sauce my pal shared with me, but it IS pretty amazing stuff. I'm very happy with it and just wanted to thank you for telling me what "the good flux" is.

[Anonymous No.1630669]

>>1628457
>>1628468
>>1628499
Hey anons, I just got my Amtec goo today. It's not the secret sauce my pal shared with me, but it IS pretty amazing stuff. I'm very happy with it and just wanted to thank you for telling me what "the good flux" is.

[Anonymous No.1630670]

>>1628457
>>1628468
>>1628499
Hey anons, I just got my Amtech goo today. It's not the secret sauce my pal shared with me, but it IS pretty amazing stuff. I'm very happy with it and just wanted to thank you for telling me what "the good flux" is.

After him not telling me, and what seemed like deliberate obfuscation of flux brands by youtube rework techs, I feel like I've been let in on a wizard secret.

[Anonymous No.1630673]

>>1630670
show joints

[Anonymous No.1630677]

>>1630670
open board
show vajoints

[Anonymous No.1630679]

Im taking my electrical journeyman test for Miami Dade County, anyone one have any tips?

[Anonymous No.1630682]

>>1630679
electronics is about combining electron devices that generate and process signals and power according to universal physical laws
sparkology is about knowing applicable code for your jurisdiction. start with RULE 0 in the OP

[Anonymous No.1630685]

>>1630673
>>1630677
I'm just using it to de-solder a bunch of components right now. Don't have a board to work on atm; just a bunch of shit to repair.

This is what my joints look like when using rosin poo.

[Anonymous No.1630737]

Since a capacitor acts as basically a short at the start should i worry about my wires being melted before it chargers?
I have 0.1F cap across my power source and the wires are rated for about .7A tops, do i need to put some resistor there or somewhere?
I know you don't have to for small caps like 1uf since they saturate way too fast, but big caps like mine will draw current for a while before they are fully fed

[Anonymous No.1630748]

>>1630737
>I have 0.1F cap across my power source
and did anything smoke?

[Anonymous No.1630749]

>>1630737
oof...
https://en.wikipedia.org/wiki/Decoupling_capacitor

[Anonymous No.1630751]

>>1630512
I'll take the hasty arrogant asshole since they won't live long enough to go on /diy/ and post stupid questions.

[Anonymous No.1630757]

>>1630737
Does this look something that shorts anything?
(dielectric doesn't conduct electricity)

[Anonymous No.1630758]

>>1630757

[Anonymous No.1630823]

>>1630757

t.never spent one hour in electronics class

[Anonymous No.1630829]

Does the marking LS on a SMD diode in any way, shape or form indicate the type of diode?

[Anonymous No.1630841]

>>1630829
Of course. Why do you think diodes are marked at all?

[Anonymous No.1630843]

Bought this old portable refrigerator and it worked before I repainted it.
No clue whats wrong with it, converter makes a buzzing sound but no cold and when I screw down the red lid it shorts to ground.

[Anonymous No.1630844]

>>1630843
Blue wire with plastic cover shorts when connected to ground but connecting where it should go, temp control gauge, it does nothing. Same buzzing sound from converter connected or not.

[Anonymous No.1630982]

>>1630844
>>1630843
where does your "blue wire with plastic cover" comes from?
Do you have multimeter to measure voltage/resistance with?

[Anonymous No.1630993]

>>1630982
Down to bottom of converter with rest of the wires. Took some damn poor photos, thought they were better.
I do have meter but I don't know enough to understand the results. What I know its getting power alright.
Should mention is dual system 12 and 230v. Currently using 12v with another converter because 230v cable is missing.

[Anonymous No.1630995]

>>1630993
I'll make a electric circuit sketch later to better understand the pics.

[Anonymous No.1630998]

>>1630539
While I appreciate the sentiment behind all this non-spoilered information, this is well beyond my knowledge, understanding or necessity; any chance of me remembering any of that 5 minutes from now was out the window as soon as you started putting in 8th grade level equations, kek. I even failed to follow what it was you were trying to demonstrate - the leftover current after all the LED's are lit? I'm a sysadmin and these ideas and concepts are so foreign to my world I only know of them vaguely from old kids' books I read.

I still don't understand though - if I connect them directly to 3 AAA batteries without the resistor, could they stand the current or would it fry them? (or is it the high voltage that's dangerous to electronics?)

[Anonymous No.1631016]

>>1630998
>or is it the high voltage that's dangerous to electronics?

When in doubt, fall back on the hydraulic analogy. Voltage is water pressure. Current is flow rate. Resistance is the restriction of flow imposed on the water by limitations of the components.

Wire = pipe
Resistor = a constriction valve along the length of the pipe. Some can be adjusted, most are fixed.
Load = a widget that uses hydro power to do work

Your LED is a load. For sake of argument think of it as a little fish tank pump that uses household water pressure to push other fluids around

The danger is the combination of voltage/pressure and current/flow. The POWER aka the amperage consumed by a circuit is what has the potential to fry components. Your little LED/pump can be overpressured and break, unless you limit the flow and pressure of water going into it. That's what the resistor is for. If you just connect it up to your main inlet pipe it's going to crack open.

You need a resistor that will adapt the pressure and flow into your LED. You choose the resistor based on the source pressure (voltage) and the power rating of your LED in milliamps and volts.

How do you figure that out? Ohm's Law and the Power Law. See anon's post you skipped over.

[Anonymous No.1631027]

>>1631016
I understand the concept of a resistor, not the math; you're trying to educate me by giving me pieces of a puzzle and asking me to complete them, and again it's appreciated, but what I really need is for someone to tell me what the final picture is of.

Fuck it I don't care if they burn out they're free, I'll just connect them as-is and see if they fry, waiting further does not serve my best interests if safety is guaranteed.

[Anonymous No.1631044]

>>1630539

why the gay-assed attempt at spoilering? spoilers are for shit that you need to hide from redditors, like when you just have to show that you saw the recent kiddies movie and you know which transgendered 6 year old wins the soccer tournament. moot once said that the reason most boards don't have spoilers is because of shit like this, where someone tries to be cute and it just shits up the board even more.

[Anonymous No.1631061]

>>1631027
Oh. Hah. I followed the thread up a bit. What you're asking the first anon answered well and simply. You didn't understand or believe him because you're an idiot, and you complain about /pol/ out of nowhere because you're a faggot.

Don't bother repairing things. Just stick with mindless consumption. Subscribe to Söylent loot crates and play with your Switch while it's still under warranty.

[Anonymous No.1631081]

>>1630998
If you connect the LED without resistor, it may uses as much current as given by the batteries.
But pass a certain point, LED convert current less to light and more to heat.
So it will heat up as much as it can.
If it can self destroy, it will gladly do so.

So you add a resistor which will reduce the available current to the LED to protect them.

If you want to learn, cut a piece or your LED string, and put it to a 5V battery with resistor, and then without.
You will see what happen and how much heat is generated.

Ho, and try to remove your fingers from your ass and learn 8th grade math you faggot. A sysadmin must know how to make division to partition disks.

>>1631044
Even if I respect your dubs, I can't say so of you.
I used spoiler to hide unimportant but interesting information.
This way, the anon could either read the answer directly, or try to learn a little bit by reading the spoilers.
If you like to watch "movie whit 6 year old transgendered soccer player" and spam reddit about it it's your problem.

[Anonymous No.1631094]

>>1631061
Opinion disregarded.
FYI, I've been posting my work in woodworking, sculpting and metal/woodwork restoration threads since pretty much when /diy/ started. Not everyone who doesn't care to learn electronics just to get a simple question answered is a complete fucking moron incapable of functioning in modern society because they're your paranoid generation's boogieman. I'm also likely a decade older than you and judging by your language you've spent too much time in the /pol/ echo-chamber. Go breath some fresh air you little zoomer shithed.

>>1631081
>try to remove your fingers from your ass and learn 8th grade math you faggot
You really have no reason being hostile - I thanked your advice multiple times, and once I realized you were trying to educate me on something I have no desire to actually learn, only get a focused answer and leave, I told you so to save you further effort. I don't know what riled you up.
>A sysadmin must know how to make division to partition disks.
That has not required any amount of block number calculation in over a decade, and with the size of storage I work in and Docker/VM's I rarely get to install an OS from scratch anymore.
Thanks again, regardless

[Anonymous No.1631098]

Imma ask here since it's an electronic project, but this is unrelated to electronics

I need to package this thing i made in a nice wooden box. I have no idea how to build a wooden box. Are there places where i can get little pieces of wood and assemble them myself? I'm completely clueless

[Anonymous No.1631099]

>>1631081
In his case "sysadmin" means "I've been playing solitaire in the same middle class welfare job for twenty years." His brain ossified back in 1987, and nothing offends him more than asking him to learn something new. Anything. Even when he asks you how to do something he wants you to tell him he already knows.

>>1631094
Shhh. It's okay gramps. You'll be dead soon.

>>1631098
Nixie?

Check out the carpentry thread.

[Anonymous No.1631103]

>>1631099
>gramps
Wait, so am I a numale soiboi addicted to switch or am I an old man who can't understand a modern boy's problems? Which of your /pol/ boogiemen am I? :^)

[Anonymous No.1631104]

>>1631099
yeah they're nixies

went full gypsy with using pure transistors instead of decoders, and that voltage step-up board is much bigger than it needs to be

[Anonymous No.1631105]

>>1631094
Anon, don't listen to those guys they're trolling you. Just whack a 10-20 and ohm resistor in series with your LED it'll be fine. LEDs are very overcurrent tolerant and the resistor is just there to soak up some extra power. No need for math, just ballpark that shit.

[Anonymous No.1631108]

>>1631104
How much current can your boost converter provide at whatever voltage your HV rail is? If it can supply over 100-150mA I'm interested in the design for my own application driving multiple IN-9s.

[Anonymous No.1631116]

>>1631103
You've got the worst trait of the former, but outed yourself as the latter.

>>1631105
He didn't ask that. He wants to know if he's going to set his sleep-number mattress on fire with a pair of double As.

[Anonymous No.1631118]

>>1630829
yes, but it can take some digging to go from marking to part number. google "smd marking ls" and see what you come up with. might be a 6.8V zener, might not. NB codes are different across case sizes and manufacturers

>>1631103
both, obviously. kek, every manufactured """enemy""" of the USA has reliably managed, in teh same breath, to be both stunningly incompetent and singularly cunning at the same time

>>1631108
how do you feel about winding your own transformers?

[Anonymous No.1631123]

>>1631118
>every manufactured """enemy""" of the USA has reliably managed, in teh same breath, to be both stunningly incompetent and singularly cunning at the same time

Amazing isn't it? Thank G-d we've got patriotic boomers to vote for more wars.

[Anonymous No.1631125]

>>1631118
>how do you feel about winding your own transformers?
Don't love the idea but it seems like it's probably the only option I have. I'm doing 12V to 180V and I've been experimenting toroids with an effective permeability of about 60 and a ratio between 10:40 and 10:90. Those are the only suitable cores I have on hand. Everything else is ungapped with effective permeabilities near 20,000 which just ends up saturating. I probably want EI cores or ER or PQ or something with an air gap and an effective permeability of somewhere between 50 and 250 I think.

[Anonymous No.1631131]

>>1631108
Can't say for sure, it powers these 3 nixies just fine but that's all I have

At 150 V, probably ~2 mA each.
I basically copied this https://www.ledsales.com.au/pdf/555_kit.pdf

[Anonymous No.1631134]

>>1631131
Oh probably not then if it's coming from a 9V battery and plus the 555 circuits have no feedback. They work, they just don't work well. I've been using switched mode controller ICs in my designs. MC34063 first and I've recently switched to using the TL494. I have a MAX1771 to play around with too.

[Anonymous No.1631169]

>>1631123
>pic related
my intelligence level and my appetite have decreased

>>1631125
>60
how big, though?
if I were doing this I'd try a few more secondary turns on something like an EE20 core that can deal with a couple dozen watts. these look good https://www.aliexpress.com/item/EE25-185-265V-85-265V-5-12-12v-or-24v-FLYBACK-BENIS-TRANSFORMER/32793617794.html

[Anonymous No.1631174]

>>1631134
>555 circuits have no feedback
Nonsense. Can you read a circuit diagram?

[Anonymous No.1631212]

>>1631174
>vout to the right of vin
also that looks like a bang bang controller. i refuse to call that feedback.

[Anonymous No.1631287]

>>1631212
>vout to the right of vin
It's to be expected since the author is using the IC's actual pinout in the diagram instead of an idealised block with Vcc and Rst at the top and Ctrl and Gnd at the bottom like god intended.
>bang bang controller
I don't think so, it's semi-linearly pulling down the control line, not just toggling the reset line with a comparator or other voltage threshold.
Though if you can show a duty-cycle feedback converter using two or less fundamental ICs (i.e. comparators and op-amps), that would be great. I looked into it a bit and I think it requires rail-to-rail operation, or at the very least some funky split-rail action which can be needlessly complicated in terms of bootstrapping.

[Anonymous No.1631290]

>>1631094
>8th grade math
It was more in the sense "Come on, you have a job and don't know basic shit? Put your ducks in row".
Saying faggot is like saying hello here (or maybe /diy is more polite? my bad if so)
>Sysadmin job
Really?
You never need to divide the total ammout of usable diskspace by the number of docker you want to run?
Or share the user's workload equally between servers or mainframe?
Put that way, it sounds retarded, oviously you don't have to anymore, programs do it for you...
Okay, maybe you will never use a multiplication in your work, but what it you want to compare per pound price of f0od for different package?
Or check that your mortgage is correct?

[Anonymous No.1631341]

if my major is electrical engineering, is it required that I do any sort of complex analysis course for my degree?

[Anonymous No.1631345]

>>1631212
it's quasi-linear

>>1631341
yes

>>1631125
is Pic related what you've been looking for? if so, feel free to steal, but note the inductor peak/rms currents and select your inductor accordingly
also use hyperfast recovery diodes if available (3A 200V with no less than 30A surge rating)

[Anonymous No.1631406]

>>1631345
Input current is too high for my tastes. Is there any way to get it down?

[Anonymous No.1631419]

>>1631406
Increasing the inductance should do the trick.

[Anonymous No.1631429]

I have IC which turns on a relay. Like 9 times out of 10 it works fine but once in a while the relay flips on and instantly off and the ic reboots. I assume this is due to the power source being weak, but if it is weak why does it only do this once in a while? would adding a cap across the power source output fix the problem?

[Anonymous No.1631438]

>>1631419
I don't think he'll get the energy transfer he needs with this controller

>>1631406
it looks like it's in the ballpark of 90% efficiency. conservatively, probably about 75% in the real world, pessimistically. that's not too shabby for a back of napkin sketch that can't run over 50% DC. add input caps, 16V SMD ceramics are cheap. current ripple is generally
or use something like a switching controller with an external MOSFET and let it sort out the details

>>1631429
/ohm/ RULE 2

[Anonymous No.1631439]

>>1631438
I was assuming he meant the RMS current in the inductor of 2.9A, which is pretty high at 12V. I doubt the nixies use anywhere close to 35W, but I could be wrong.

Also why don't people just have converters from mains voltage instead of going to the trouble of stepping down to 12V only to boost it back up to what's quite close to the peak voltage of US mains?

[Anonymous No.1631461]

>>1631438
>in the ballpark of 90% efficiency
Where did you get that from? The simulated efficiency is about 58%.
>>1631439
>why don't people just have converters from mains voltage
A simple isolation transformer would not be complicated enough and it would work. Not /ohm/ compatible.

[Anonymous No.1631465]

>>1631461
>isolation transformer
Who said anything about isolation? A single diode rectifier and your neutral reference would be right as rain, provided you use a non-reversible plug. Twice the filter capacitance is a small price to pay.

[Anonymous No.1631469]

>>1631439
dude had some bar graph nixies with a lot of segments iirc

>>1631461
pulled it directly out of my ass. you are, of course, correct

>>1631465
but far from current- or voltage-regulated

[Anonymous No.1631472]

>>1631469
>far from current- or voltage-regulated
Dropper resistor and a zener. You happy now?
I'd personally quite like it if there were common HV linear regulators, like a "78150" or "78320". They'd be handy for getting rid of the 50/60Hz ripple for low-current things like neons and phantom power for diy audio stuff.

Off topic, could you turn a simple inductor (no magnet) into a guitar pickup by running a constant current through it?

[Anonymous No.1631479]

>>1631465
>Who said anything about isolation?
I did because I have 230V and a reversible F plug, L and N can be anywhere. The type C plug is my friend because you can have three of them in a single socket.

[Anonymous No.1631484]

>>1631479
Makes me wonder who designed those plugs. It's not like they need to be compact, since you've got an entire fucking wall at your disposal.

[Anonymous No.1631486]

any free drawing tool with this quality???

[Anonymous No.1631489]

>>1631484
>who designed those plugs
Certainly not the copper barons.

[Anonymous No.1631495]

>>1631472
>simple inductor (no magnet)
Yes, steel cores and current. Modulating the current modulates the volume.

[Anonymous No.1631508]

>>1631486
KiCad has something similar to that when doing nested schematics, but I don't think it's quite that symbolic unless you really put effort in. Still probably worth a shot, and I imagine it has some page layout options for designing a presentable schematic, as opposed to just cramming parts in and around the schematic outline in order to generate a PCB layout.

>>1631495
But they need a phantom power supply, right? Since the current density would be proportional to signal:noise ratio, I wonder what sort of current they settle for? There a name for that sort of pickup?

[Anonymous No.1631516]

>>1631508
Phantom is balanced, pickup is not. No name so far, too new. It was suggested on 06/17/19 at 10:33:24 UTC by a certain Anonymous.

[Anonymous No.1631738]

does overcharging car batteries cause water electrolysis releasing hydrogen or does it fuck shit up as well?
currently charging a ded battery at 13v and its been taking 300mA for 2 days now with very little difference, is it possible it's just making hydrogen?

[Anonymous No.1631747]

>>1631469
Glorious soviet multisegment electroluminescent display

[Anonymous No.1631761]

>>1631738
>car battery

>charging a ded battery at 13v and its been taking 300mA for 2 days now with very little difference


Alternators output over 14 volts at many amperes.
300ma at 13 volts will take weeks to charge a dead auto battery IF it can be charged.
You need several amps (2 to 8) at ~15 volts to get it going again.
Several hours at this rate then adjust to voltage down to 13.8 volts for extended period to finish the charge.

Easy Mode:
Get an actual automotive battery charger.

[Anonymous No.1631774]

Dumb question maybe, but does anyone know where I can buy like a box or bag of assorted components like this? I always need some random resistor or cap, and other than order like ten of them on Digikey and wait a week, I don't know what else to do. You can't just go to radio shack with a list and buy what you need from their big chest of component drawers anymore.

[Anonymous No.1631778]

>>1631774
You can get cheap resistor/capacitor kits on Ali/ebay.

[Anonymous No.1631835]

>>1631486
inkscape
no, it's not worth a try to try to use KiCAD to generate, when there are better tools that are more fit for purpose

>>1631774
order full assortments with most/all values on ali for cheap

[Anonymous No.1631843]

>>1631778
>>1631835
>ali
Don't the chinks sell counterfeit everything?

[Anonymous No.1631847]

>>1631843
It's cheaper to just send you a real resistor than making a counterfeit.

[Anonymous No.1631853]

>>1631847
Okay. Thanks anons.

[Anonymous No.1631872]

>>1631843
100 for 4 cents, dude. not even worth faking

[Anonymous No.1631882]

I have this VCA design here.
At first, it completely clipped the negative half of the waveform (triangle wave), but the positive output went up to ~7 volts from a 5 volt input signal.
The output amplitude can be controlled by changing the voltage in the upper left corner.

however...

[Anonymous No.1631887]

>>1631882
I modified the design by replacing the resistor to ground with another darlington pair, but PNP.

It worked, it now has both sides of the waveform.
But, the "amplitude" voltage control is now much more sensitive and also works primarily in a negative voltage

I don't exactly/actually know why what I did worked, what exactly did I do

[Anonymous No.1631893]

>>1631887
two notes:
the Ibias and Iabc inputs are current, not voltage. it's right in the name of the input. treat them as such
OTAs are single-supply devices and don't give a fuck about what you think is ground
please review existing VCA circuits for guidance instead of bumbling around and asking what you accidentally made

[Anonymous No.1631897]

God I hate microchip/atmel. I shouldn't need to patch my J-Link a demo board to get around a proprietary on-board debugger. At least I got it to work, so there's that.

[Anonymous No.1631922]

>>1631897

so tell us how to patch it, so it becomes a DIY post instead of a whining/bitching on-my-period post.

[Anonymous No.1632003]

New to /ohm/, has anyone had success with pic related? I want to control several switches plugged into a remotely accessed laptop via SSH.

The manufacturer's GUI doesn't pick up the board and I can't get any of the other options on Github to work either. Pretty sure it's not a driver issue. Pref to run laptop on Ubuntu.

[Anonymous No.1632011]

>>1632003
is the FTDI detected by the host machine?
is the user in the dialout group? (can't remember if it's the only group needed, maybe tty)

[Anonymous No.1632017]

Hi /diy/,
Is my design sound? I'd like to operate a beacon light with a dark activated switch.

The IC's circuit I used is taken straight from the spec sheet in common applications for lm3909 section. Im not worry about that, it worked before. I'd like y'all to check the switch line. The photo-transistor with direct sunlight will pull down the voltage coming in the base of the transistor, hence the transistor will be in OFF mode. When sunlight is blocked, the voltage is no longer blocked (current flow is reduced) or so I think... I took a snippet of the common emitter phototransistor circuit. Do I need to calculate voltage gain coming to the base or the 100kOhm is too much? The current gain is about 400-500. The LM3909 directs about 1mA so I want to use the 100kOhm as a current limiter.

[Anonymous No.1632031]

>>1632017
put the load on the collector instead of the emitter so that the switch can turn off all the way
other than that, sure, build it and see what happens

[Anonymous No.1632033]

God damn it, why does the buck conversion from 230v to 5v must be so big. The smol 3x3cm converter i got from chinks is wated for 700ma but shits itself around 500ma, so i have to use one that is 3 times bigger which works fine bus is two times larger than all the rest of the parts in my project combined
fucking hell, just make a law that outlets at home are allowed to only run 50V dc tops and all is gud in diy world, also way fewer fatalities

[Anonymous No.1632034]

>>1632033
buck converters are not isolated. lern2nomenclature
400V caps are gonna be kinda large. still, a real off-line non-isolated buck converter would offer more like 12W in that amount of space, see ST's VIPerx6 switchers
>he forgot to apply the chink derating factors for his product
procurement error

[Anonymous No.1632043]

>>1632034
>buck converters are not isolated.
It literally has buck converter in the product title
>ST's VIPerx6 switchers
unless chinks on ali sell it for pennies it is not an option
also i don't like nonisolated ac dc converters very much, since if you touch them wrong then will fill you with the hurt light
i will just have to suck it up and use the larger convertors which the chinks probably harvested from old phone chargers since they all come with soldered snipped off wires on the output contacts

[Anonymous No.1632049]

>>1632043
>unless chinks on ali sell it for pennies
Pic related

[Anonymous No.1632058]

>>1632049
I looked it up and it looks too god to be true, a small chip that let's you hook up an IC directly to an outlet? And it seems it is, it appears that you need to add a bunch of other parts to achieve 230V AC -> 5V DC conversion, so that won't help me much, i need something simple where i can basically just solder couple of wires between it and say an arduino an am good to go.

[Anonymous No.1632094]

>>1632017
>Is my design sound?
No, it's floating.

[Anonymous No.1632099]

What schemes have y'all used in the past to convey state information about an embedded device through an RGB LED? My current implementation just blinks a given color for its associated interrupt on the device. My thinking is that since I could convey a byte of information per LED modulation, it might be worthwhile to have an designated timer for the LED to emit debugging/state information with 3-channel PAM.

[Anonymous No.1632104]

>>1632099
if you can make a convincing and distinct brown and gray, you can blink out base 10 numbers via the EIA resistor color code

>>1632049
personally I have a 12V@10A supply under the desk and I just run stuff from it
anyway, you should avoid running components or modules very near their maximum ratings, just in case some tolerances all work out against you. if you need 700mA, add ~50% margin, round to 1A. these are slightly less likely to be chinked, not least because direct from the manufacturer. a little more than pennies, sorreh https://www.aliexpress.com/item/1pcs-new-ac-dc-converter-220V-5V-12V-24V-5W-ac-dc-power-supply-module-quality-benis/32990299677.html

>>1632058
that's the catch

[Anonymous No.1632158]

>>1631897
Its... its a demo board.
That's why it has on onboard debugger.
They have options without onboard stuff.

[Anonymous No.1632160]

>>1632003
>>1632011
Check to see if /dev/ttyASM0 (zero) exists, that will most likely be the board. (Or ASM1, 2, ect if you have other FTDI stuff hooked up)

You do also have to be in the dialout group, and under some circumstances, you may have to sodo a program to work.
I use the screen program to do quick serial communication to FTDI type chips.

[Anonymous No.1632229]

batteryanon here, got a 19v laptop charger and a 5ohm resistor, now charging at a little over 1A
i noticed the battery voltage while charging went down from ~14v to ~13 over the course of the day, why is that?
the charger is still outputting 19v
is it possible it's getting desulphated and the internal resistance is decreasing or is it gonna blow up?

[Anonymous No.1632254]

>>1632229
a battery's resistance is increasing not decreasing with age.
just like resistance to self improvement in humans

[Anonymous No.1632268]

>>1632254
could you tell me why the voltage across the battery is decreasing and increasing across the resistor?

[Anonymous No.1632285]

>>1632268
It's beginning to actually take the charge.
It's loading the charger more now.

[Anonymous No.1632295]

>>1632285
is it?
>before
resistor voltage 5v
battery voltage 14v
supply 19v
>now
resistor voltage 6v
battery voltage 13v
supply 19v

[Anonymous No.1632297]

>>1632295
the more load on the circuit past the resistor, the higher the voltage across the resistor will be.
Put a 6 volt battery on it instead of a 12 volt and ~13 volts will be dropped across the resistor as long a the charger stays at 19 volts.
That's just how it works. If you aren't aware of this perhaps you should just get a real battery charger for your own protection.

[Anonymous No.1632300]

>>1632297
i know, was just wondering WHY it's taking more current now
the cell voltage probably didnt go down so i'm guessing it's decreasing the internal resistance by dissolving shit off the electrodes or something

[Anonymous No.1632323]

>>1632300
I have a normal 'not smart' auto battery charger.
It's rated for 8 amps.
If I put a 'dead' battery that's really dead (< 6 or 8 volts) on it, most likely it will show almost no current being drawn on the meter.
After a while it starts crawling up and eventually makes it to 8 amps.
As it actually starts reaching full charge, the current starts falling back down until it goes to < 1 amp.

What you're describing in normal for a really fucked up battery.

[Anonymous No.1632372]

>>1632300
did you measure current?

>>1632323
i don't know what kind of batteries yinzth [1] are talking about but what you describe sounds like a 'charging profile', i.e. const voltage first then when it reaches a certain threshold it switches to a constant current and then the current will slowly decrease as the batter is almost fully charged. it is not just due the ohm's law. the charger controls voltage and current intentionally.

i don't know what charger this anon is using: >>1632295 but sounds it is a constant current charger.

[1] you both

[Anonymous No.1632406]

>>1632372
>'charging profile'
>>1632323
>a normal 'not smart' auto battery charger
transformer, rectifier, ampere meter

[Anonymous No.1632442]

Beginner here, experimenting with guitar effects.

What topology is this? Does anyone mind hand-holding me through how it works (in intuitive terms)?

[Anonymous No.1632457]

>>1632442
try redrawing it in the form of two common-emitter amplifiers, the first pnp, the second npn. input voltage drops, causes pnp to conduct more, pulling its output (across the 100k) higher, turning npn on more, pulling its output lower
when drive control is at highest resistance, 2N3906 emitter is supported by less capacitance (22uF in series with 0.1uF ~= 0.1uF), thus the npn output can push it around in the same direction as the input, providing negative feedback as the emitter voltage cancels some of the input and along with it some of the gain. with drive control at lowest resistance, the emitter now has has a bigger capacitor (stiffer spring) to push against, reducing the influence of the 47k feedback loop and increasing total gain
does that help?

[Anonymous No.1632463]

>>1632457
That definitely helps, thanks. I was able to identify the 2N2904 as being used as a common emitter amplifier, but I was confused by the feedback path and the absence of a collector resistor on the 2N3906. What difference would adding one make?

[Anonymous No.1632469]

>>1632463
>absence of a collector resistor
Not absent, it's the 100K resistor in parallel to the input resistance of the 3904.

[Anonymous No.1632472]

>>1632469
Of course, you did mention and then I blanked. Thanks again for your help.

[Anonymous No.1632547]

>>1632442
i am not that good at reading schematics but this one looks really cryptic. you really need to redraw it more according to standards and it will become much easier to read.

[Anonymous No.1632561]

>>1632547
Having two solid voltage rails might result in a lot more crossing wires, but I agree that it would help with the interpretation of the diagram as seperate blocks in a linear sequence.

[Anonymous No.1632595]

>>1632372
i'm using a laptop 19v power supply and a 5ohm series resistor
>did you measure current
yes, it increased as per ohms law

disconnected it stayed at 11.8v so i hooked it up to a 12v supply overnight with no problems
weird thing is an hour after i stopped charging about 10ml of the electrolyte came out but it didnt heat up or anything
what the fuck is going on

[Anonymous No.1632597]

>>1632595
>an hour after i stopped charging about 10ml of the electrolyte came out

batteries burp after a feeding, just like babies.

[Anonymous No.1632660]

>>1632547
Yes, I have redrawn it in the past because its layout is so strange.

[Anonymous No.1632666]

>>1632595
>disconnected it stayed at 11.8v
It has a dead cell
https://www.youtube.com/watch?v=_8qgZoovWHI

[Anonymous No.1632676]

I have a 5 volt relay, and i tried to run it with 3 volt and it works, but the click it makes when closing is significantly less loud than when it is closing with 5 volts
will that be a problem? i am using it to trigger 220 volt

[Anonymous No.1632689]

>>1632676
Not recommended. Pick-up voltage is usually min. 75% of nominal.
You trigger a circuit, not a voltage.

[Anonymous No.1632713]

>>1632033
>>1632043
>buck converter
>isolated
As it's name implies topology - buck converters are non-isolated.
There are variants like fly-buck but it's rare as biggest point of buck converters is they are cheap
The term you are most likely looking for is flyback

>why does the buck conversion from 230v to 5v must be so big
It does not. While one in pic only outputs about 100mA, I had one in identical size output about 1.5A@5V so size is not a problem.

There are vertical transformers where size further can be reduced, if isolation is not a concern - even smaller cores like EE8 can be used

[Anonymous No.1632716]

>>1632713
also, it's flyback (not buck) as buck converters usually have a lower current limit

[Anonymous No.1632734]

>>1632716
The buck stops here and nothing is flying back.

[Anonymous No.1632737]

>>1632689
well if it clicks it means the contacts are closed and holding them closed needs only 15% of the original 5V , so what problems could there be?

[Anonymous No.1632739]

>>1632737
contact lifetime; erosion due to slow closing.
click comes after contacts are closed.
don't care, just do it.

[Anonymous No.1632754]

>>1632737
perhaps it might not close every time?
it is like asking you to live on 3000 calories instead of 5000 and fly commercial airplanes. one of those days you will pass out due to hunger and crash the plane.

[Anonymous No.1632757]

>>1632754
>if I don't eat twice my recommended daily allowance of calories I'll pass out
wat

[Anonymous No.1632759]

>>1632757
nobody should eat less than 5000 a day. i mean it is possible to stay on a starvation diet of like 3000 but you will have hunger pangs and will eat another 2000 before going to bed.

[Anonymous No.1632767]

>>1632759
I'm a doctor, and I think you're getting your units confused.

[Anonymous No.1632778]

>>1632759
I'm beginning to understand the obesity epidemic. I run on 2000 for ages.

[Anonymous No.1632786]

>>1632767
>>1632778
i mean imperial not metric if that matters. i am in the us. 2000 is one meal.

[Anonymous No.1632792]

[Anonymous No.1632797]

>>1632786
There isn't an imperial vs. metric problem with calories, just a hidden 'kilo' multiplier. If you're using kilojoules (which you don't in the US), it's 8000.

I now suspect you've memorised the RDA values wrong. If you're eating 5000kcal a day, you need to stop immediately.

[Anonymous No.1632818]

>>1632797
In the SI world 1 cal is 4.184 Ws=J, which means my 2kcal/d or 8.368kWs/d fuel the machine for an average thermal output of 96.8W, very close to the estimated 100W per person.

[Anonymous No.1632823]

>>1632818
That's interesting. 2000kcal/day is the correct number, too.

[Anonymous No.1632824]

>>1632797
>eating 5000kcal a day
is physically impossible

[Anonymous No.1632826]

>>1632824
That's what you think. I had a patient who weighed a quarter of a metric tonne recently.

[Anonymous No.1632827]

>>1632823
This is confusing. In my world 2000kcal are 2Mcal like 2000kΩ are 2MΩ.

[Anonymous No.1632829]

>>1632786
>i am in the us. 2000 is one meal.

[Anonymous No.1632833]

>>1632827
Se my earlier post about the hidden 'kilo' multiplier and read the relevant Wikipedia page. When people talk about calories in food, they mean Calories (note the capital), which are actually kilocalories.

>>1632829
My thoughts exactly.

[Anonymous No.1632840]

>>1632829
>>1632833
inb4 muh fastfood
go to an average mexican restaurant and the average meal there in a range of 1500-2000 kcal easily. wash it down with a couple of beers and have an ice cream desert and you are at 3000.

[Anonymous No.1632844]

>>1632840
Yes, despite that being your whole day's calories. And it seems that some people believe that that is healthy, or that you'll pass out if you eat 3000kcal a day.

[Anonymous No.1632855]

>>1632824
>is physically impossible
Though Phelps later admitted the 12,000-calorie figure was an exaggeration, there is truth in that Olympic-level swimmers burn around 3,000-10,000 calories a day, depending on the intensity of their workouts. No surprise then, that the likes of Lochte and Phelps consume about 7-8,000 calories a day—four times the average adult male’s diet.

[Anonymous No.1632860]

>>1632855
that's very close to my daily menu, yes.

[Anonymous No.1632896]

the battery is now charging at 12.2v and only drops to 12.0v disconnected
with a 5 ohm load the voltage drops to about 11v
its almost behaving normally now

how dangerous is dilute sulfuric acid? some of it spilled earlier and i got most of it but i'm worried about tiny drops evaporating the water off and becoming concentrated
if the volume is small enough does all the acid do its thing and dissapear or will my hand melt off if i touch my desk in a week?

[Anonymous No.1632899]

>>1632896

[Anonymous No.1632902]

>>1632899
i started at 6v
does that mean it was at negative charge

the acid is definitely getting more concentrated as it's charging, started off being slightly sour and now it tastes like metallic lemon

[Anonymous No.1632904]

>>1632902
found the future street criminal

[Anonymous No.1632922]

I’m trying to build an amplifier for my electric guitar and i’ve been following the Forest Mims Getting Started in Electronics book. He keeps showing the variable resistor with three leads. R2 is the variable resistor here and im not sure how this works, since i don’t get why a variable resistor has 3 leads. does it mean the resistor can take in 2 values

[Anonymous No.1632931]

>>1632922
think of it as two resistors in one. you are increasing resistance on one side while at the same time decreasing on the other side (as measured relative to the center tap).

[Anonymous No.1632939]

>>1632922
also i have to say it is an extremely horrible and confusing way to explain biasing. that wiring with crossed non-connecting wires looks very confusing. you can just get rid of R2 and connect the two crossing wires and tweak R1 and R3 instead.

[Anonymous No.1632960]

/ohm/, is a fume extractor from chinkland sufficient? Is a fan with a carbon filter sufficient, or should I vent the exhaust out through a window? Or should I find a different solution altogether?

[Anonymous No.1632964]

>>1632922
>He keeps showing the variable resistor with three leads
https://en.wikipedia.org/wiki/Potentiometer

[Anonymous No.1632966]

>>1632939
>that wiring with crossed non-connecting wires looks very confusing
so too, apparently, is the sideways text
>R2 controls gain (volume)

>>1632960
since fume extractors are little more than fans in a frame with a space to hold a charcoal/foam sheet, you should be fine. any fan would be enough for a non-OSHA space, assuming enough air exchange via passive ventilation

[Anonymous No.1632977]

>>1632939

[Anonymous No.1632998]

Hey, I'm designing a headphone amp and I would like it to automatically sense what load impedance is connected, send a control signal to a transistor or relay to adjust the gain based on the load impedance sensed, and light up an LED or seven segment display displaying the load impedance.

The problem is I'd like to be able to load sense constantly. Even while playing music. I'm not sure how to achieve this. I thought about maybe something like a wheatstone bridge with the amplifier in the middle and a high frequency (much higher than audio frequency) low amplitude sine wave connected between two legs. Buffer the other two legs, add a high pass filter, and a differential amplifier. That's about as far as I got. Add a big inductor between the power amplifier output and the bridge to prevent as much high frequency signal as possible feeding back. This would negatively affect the high frequency response somewhat but it shouldn't be too bad if I pick the inductor carefully. Maybe do a T-network or something too.

Is there a better way?

[Anonymous No.1633001]

>>1632998
what's your schematic? can't you sense current? by measuring a voltage drop across a tiny resistor and feeding it to an instrumentation amp or a dedicated current sensor?

[Anonymous No.1633002]

>>1632998
what kind of meme-tier headphones do you have whose sensitivity changes on a minute-to-minute basis

[Anonymous No.1633007]

>>1633001
I can do that I guess. Measure and peak detect load current and voltage send to a micro to calculate resistance. I'd need two ADCs for that though no? Or I'd need to switch one really fast. Seems like that'd be inaccurate. I suppose I could use an analog multiplier then I'd only need one ADC but they're expensive. It's an idea. No schematics yet. I wanna to run this idea by people to see if it's possible before I dive into it. I do have amplifier early revision schematics but nothing for the output sensing yet.

>>1633002
I don't. I have various different cans with different impedances and it'd be nice to have an amplifier that automatically adjusts to an optimal output level to match whatever I have plugged in. Right now my current amp can't push enough power into my cans for my liking. On the other hand should I plug in my earbuds for whatever reason it could push enough power through to destroy them if I don't turn it down first.

[Anonymous No.1633024]

>>1633007
measuring on plugging and before activating the amp: measures the metric of interest instead of some higher-order derivative, is easily done with a quick imposition of a few mA dc, could be integrated with the anti-pop output disconnect relay (if used) so the measurement and audio reproduction stay well out of one another's way, if you can detect output opens easily and quickly, you can just pop the protection relay and keep running the detection process until you see something
measuring continuously: Xl = 2 * pi * f * L, Z = Xl + Rcoil, L = dependent on driver construction. if you're trying to use ac to sense dc resistance you'll therefore have to vary the frequency to solve for R, and also hope that L doesn't change from millisecond to millisecond due to voice coil position or turn capacitive at your ultrasonic test frequencies

[Anonymous No.1633027]

>>1633007
personally, I'd just add a low-level output jack with a resistor pad and label it "chinkshit and other consumer crap" lel

[Anonymous No.1633044]

>>1633007

seems a simpler solution would be to place a small resistor in series with each headphone so they all sound the same to you irrespective of impedance or physical proximity to your head-bone.

[Anonymous No.1633085]

>>1633044
and, if one simply must cock it up with complexity for shits and giggles, one could always place an RFID tag in/on the connector

[Anonymous No.1633098]

>>1633007
>peak detect load current and voltage
I don't think you'd need to detect both current and voltage. I mean you'd measure voltage drop across a resistor to sense current. I think you only need current and you can infer your load resistance from that. You can measure it with different loads. It should be a linear dependence. And yes using a micro would help. You can calibrate your ADC for different voltage thresholds that correspond to different current values for different load resistances. Let's say you solved this. How are you going to adjust the gain automatically? What is your micro going to do? You'd need some sort of a voltage controlled resistor? A jfet? Or PWM with LEDs/optocouplers?

[Anonymous No.1633100]

>>1633098
How can I infer my load resistance from just current? I mean, yeah with just a constant current source I can tell if my load resistance changes but I can't measure it's actual value. If I want to figure out the load resistance to the nearest ohm would I not have to measure the current and voltage and do Ohm's law in the micro (most likely after having to scale the current reading by some factor)?

[Anonymous No.1633136]

just stumbled across a video for homemade liquid tin https://www.youtube.com/watch?v=Hsw3lOnHaas

[Anonymous No.1633161]

>>1633136

seems to work but how do i get my dick out of the beaker?

[Anonymous No.1633166]

>>1633161
you don't

[Anonymous No.1633308]

>>1633100
I am not quite clear on what you are trying to achieve. Let's say you know your resistance. Then what? You adjust the volume? So essentially you are attempting to regulate the output current? By how much? Two different pairs of headphones may have the same impedance but one of them may still sound 'louder' due to the sensitivity and/or size. And that difference may be perceived differently based on the current volume setting. Also I don't understand are you plugging in different headphones or you are expecting the impedance of your headphones to change in real time??

[Anonymous No.1633316]

Software guy here. Could I control an LED grid some kind of frequency spectrum magic and two input waveforms? Like each LED has two bandpass filters tuned to its particular position on the grid and if they're both active it turns on?

Also can it be done digitally?

[Anonymous No.1633324]

>>1633316
or like a normal person you could use shift registers

[Anonymous No.1633328]

>>1633324
Just exploring my options. I've looked into shift-registers and a bunch of other IO-extenders but I feel like this could have some nice properties if it worked correctly.

[Anonymous No.1633345]

>>1633308
I'm plugging in different headphones. I have different ones ranging from 8-600 Ohms and I want a readout of the current impedance plugged in. Plus I want the amplifier to switch to a different feedback network that provides a higher gain when a higher impedance is plugged in. I'll probably have 3-4 different feedback networks for different impedance ranges and will switch them with a relay. Of course there will still be a volume pot so I have some degree of manual control but the base gain will need to be higher to drive the same amount of power through a higher impedance.

[Anonymous No.1633421]

>>1633328
such as?
some nice properties you definitely don't get with that setup is spectral efficiency, power efficiency, or response time
there are a wide variety of shift registers dedicated to LED driving, which include nice things like trimmed and matched current limiting (so no dropper resistors), sometimes PWM, and occasionally some multiple-row memory. many of them even share the same pinout/footprint. what size matrix were you considering?

>>1633345
so the real-time continuous measuring, instead of just a connection-sense and one-shot measurement, is just gold-plating?

[Anonymous No.1633422]

are there IC filter that operate in the audio frequency range? ~0-20khz is what I'm looking for

[Anonymous No.1633429]

>>1633422
no, you have to build one
https://www.electronics-tutorials dot ws/filter/state-variable-filter.html

[Anonymous No.1633432]

>>1633422
Yes. It's called "literally any op-amp ever."

>https://en.wikipedia.org/wiki/Electronic_filter_topology#Active_topologies
>https://en.wikipedia.org/wiki/Sallen%E2%80%93Key_topology

There's also some switched capacitor filters and there's also chips like the MAX274/275 which are highly configurable continuous-time active filter and allow for 4th and 8th order, Butterworth, Chebyshev, and Bessel filters. They are expensive though, like nearly $10 a pop and they require a metric crap ton of external resistors to set the different parameters of the filter.

[Anonymous No.1633434]

>>1633422
sorry, I lied
https://www.digikey.com/product-detail/en/texas-instruments/UAF42AP/UAF42AP-ND/251221

[Anonymous No.1633442]

>>1633421
Yeah you're probably right. I'll look into doing PWM on a shift register which I didn't think could be easily achieved.

[Anonymous No.1633443]

>>1633345
then why do you need to measure continuously??
just measure as you plug them in. so you are in a "measurement mode" then select the network and switch to "play".

[Anonymous No.1633447]

>>1633443
I don't want to have to manually switch modes every time. There's no point in even having any sensing circuitry if I need to do that. I could just have a switch. It probably does not need to measure continuously but at the very least it should be able to detect a disconnect, trip a relay to disconnect the output of the amp, enable the load sensing circuitry, wait until it stabilizes, disconnect the load sensing circuitry and hold the load impedance in memory or have an LED circuit that latches or whatever, then re-connect the audio.

[Anonymous No.1633448]

>>1633443
Look the bottom line is I don't really care if I NEED it or not. It's my own /diy/ design and I want the feature.

[Anonymous No.1633455]

>>1633448
>It's my own /diy/ design and I want the feature.
>so just shut up and tell me how to design it

never change /diy/

[Anonymous No.1633458]

>>1633447
Weill I didn't mean manually. i mean when there is no load you are in an input sensing mode. Once load is sensed and resistance is measured, the play mode is triggered by your circuitry/micro. But it is a moot point anyway since you want the continuous measurement "feature".
>>1633448
but the impedance will remain constant as long as the headphones are plugged in. You can measure it once and then just pretend that the feature is working as expected.

>>1633455
>how do i design this, lads?
>hey it is my design, don't tell me what to do!

[Anonymous No.1633470]

>>1633345
>I have different ones ranging from 8-600 Ohms and I want a readout of the current impedance plugged in
How is that going to help you? I have a pair of 300 ohm ones and when I plug them into my laptop they sound louder at any given volume than your average 50 ohm earbuds. I think you need a video camera based image recognition rig that would read the brand on the label and also measure the size (detect earbuds vs full size cans etc) and trigger the appropriate circuitry. Be careful though with that automatic volume adjustment or you may accidentally crank it up too much and those dbs will crush your cranium.

[Anonymous No.1633494]

>>1633447
that's a somewhat saner design, as you can time amplifier feedback control changes to avoid transients reaching the load
anyway, I'll spare you the 9004.5 hours in MS Paint of drawing a block diagram... one of which you should have thought through, drawn and posted in the first place, your design request involving interface to existing circuitry which quite probably will affect the exact means by which your requested feature would be enabled, and this being an image board and all, and not reddit

[Anonymous No.1633505]

>>1633442
>PWM on a shift register
how about pulse density modulation instead? you can transpose the bits of each channel's brightness and output the bit slices at bit-weighted intervals, with the same resultant average on-time, replacing a lot of counting with a little pre-calculation, which becomes even more important at higher bit depths. Pic related

[Anonymous No.1633509]

What's it called where
>spdt slide switches
>on one kind, during transition between poles, the contacts will be both ON
>on the other kind, during transition, they will be both OFF

[Anonymous No.1633510]

>>1633509
>on one kind, during transition between poles, the contacts will be both ON
make before break
>>1633509
>on the other kind, during transition, they will be both OFF
break before make

[Anonymous No.1633511]

>>1633509
use case to better describe what I mean

you're modding a 5v portable electronic device to switch between USB power and battery power.

You need to get a switch such that when you flip the USB/Battery switch, the terminals will both be off during the transition to avoid sending 10 volts into the board

[Anonymous No.1633512]

>>1633510
thank you

[Anonymous No.1633564]

>>1633511
you're thinking of series connections when the make-before-break switch would in fact make a parallel connection. with both contacts made, the lower voltage source would receive current from the higher-voltage one unless the lower voltage source were designed to block that current. that could be a big deal depending on the design of the lower voltage source, the dual-make time, and how much current is available: a stack of 4 NiMH supplying 4.8V will take it like a honey badger, a lithium rechargeable battery could go full triggered Fukushima on you

[Anonymous No.1633596]

>>1633316
Analog bandpass filters are a pain, require a bunch of passives, and op-amps too if you don't want to fuck about with inductors and/or shitty Q factors. With digital signal processing it's easy stuff, assuming your data is in the form of a series of numbers from an ADC, but you'd have to convert that into analog again to get the same visual effect, which would be a pain even with PWM+low-pass filtration if you had more than a few LEDs.
You're likely better just doing an FFT and feeding that data to your LEDs directly or with shift registers. Probably with shift registers, if you want more than 10 LEDs total. With good enough programming you can almost certainly recreate whatever you were going for with analog filters, with a powerful enough MCU. Something like a STM32 would be plenty, and have a pretty good ADC if I recall.

[Anonymous No.1633763]

I bought some ac to dc converters from chinks to power my arduinos and they work fine, but sound like tinnitus, is that normal?

[Anonymous No.1633767]

>>1633763
that's generally normal when you overload them, and (with some designs) when you underload them

[Anonymous No.1633770]

>>1633767
Yes, cycle skipping at light load. Increase load to hear if it disappears. If not try a potted converter.

[Anonymous No.1633776]

>>1633770
>potted
you mean sealing it in epoxy? won't it overheat?

[Anonymous No.1633796]

>>1633776
Well considering he's suggesting you buy a seperate converter that's already potted, I imagine it would have those tolerances already built in it. Not to mention you're underloading your converter anyhow so it probably wouldn't reach thermal maximum, and the heat sink for the FET could easily be left uncovered. I believe the whine is coming from the inductor, which could probably have its windings slathered in epoxy. Provided it's not already getting too hot, that is.

[Anonymous No.1633822]

I'm looking for an IC, circuit, something something that will let you run a circuit off battery, but also let you charge the battery while the circuit it running.
Kinda like a cellphone, you can charge and use it at the same time.
For the life of me I can't find anything that lets you charge a LiIon, but also powers the system it is connected to at the same time.

I'm not too certain about power limits, maybe in the 5V 2A region?

[Anonymous No.1633828]

>>1633822
I have used bq24195 with fine results

[Anonymous No.1633843]

>>1630146
>Am I endangering myself by just connecting them to a live AA battery
Holy shit, come on anon, use your brain.
I'm sure you've held an AA battery longways between your finger and thumb before. Did you die?

[Anonymous No.1633847]

>>1633822
Load sharing chargers are cheap now.
https://www.aliexpress.com/item/MCP73871/32779483651.html

[Anonymous No.1633851]

>ordered PCBs came
>realized my custom footprint's through hole for a few break out boards have the wrong sizes
>had to drill them wider with a dremel and a 1mm drill
>now only the through holes connected to ground conduct
How could this happen? My drilling was precise
Any way to fix this?

[Anonymous No.1633854]

>>1631098
Not an expert by any means - but from what I know from doing woodworking at school:

You can make a simple box by using finger joins (pic related) for all the sides and then adding a top and bottom.
To make the finger joints you'll want to use a coping saw, if you look at pics you'll see it has a big arch over the blade which allows you to cut at any angle, unlike a regular saw where the big metal blade would get in the way.
You basically mark out the fingers and then hack away all the wood you can out of them using the coping saw, then use a file to remove any excess and clean them up. Then you piece the box together, add glue between the joints and clamp. You can then glue + nail a thin sheet of MDF to the bottom of the box as a base, and then make some kind of lid for the top.

[Anonymous No.1633857]

>>1633851
if it's two layer board - just scrape some soldermask nears pins and resolder
If it's 4 layer board and pins connect to internal layers - they you have to run some wires

[Anonymous No.1633859]

>>1633851
>How could this happen?
What do you think?

[Anonymous No.1633863]

>>1633857
good idea thank you
>>1633859
I guess the vibrations from the drilling ripped apart the trace near the pins

[Anonymous No.1633870]

how would i go about making a current meter from a mini voltmeter
i was thinking a low value resistor, feeding the voltage across it into an opamp, outputting into the voltmeter and then tuning the gain so it's accurate
is this a bad idea?

[Anonymous No.1633877]

>>1633870
>is this a bad idea?

it's the simplest and most obvious way to do it, so it's a bad idea, coz nobody's gonna be impressed by that. do like the earphone guy and built insane complexity into it, with at least two computer boards.

[Anonymous No.1633885]

>>1633877
>at least two computer boards
his concept is bs and he will not build anything

[Anonymous No.1633907]

>>1633851
>>1633863
I made a pcb to avoid this mess
Looks better than my through hole board thing anyway

[Anonymous No.1634002]

>>1633885
Fuck you. I'll show you how wrong you are fag. In fact I'll build the original that measuress continuously in real-time with an audio signal applied. I don't need to but I will anyway to prove to you how wrong you are.

[Anonymous No.1634053]

>>16340>>1634051
1634051
51>>1634051

>>1634>>1634051
051
>>16>>1634051
>>1634>>>1634051
>>1634051
>1634051
051
34051
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>>1634051
>>1634051
51
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>>16340>>1634051
51
1

[Anonymous No.1634586]

>>1627131
Dear GOD/GODS and/or anyone else who can HELP ME (e.g. MEMBERS OF SUPER-INTELLIGENT ALIEN CIVILIZATIONS):

The next time I wake up, please change my physical form to that of FINN MCMILLAN of SOUTH NEW BRIGHTON at 8 YEARS OLD and keep it that way FOREVER.

I am so sick of this chubby Asian man body!

Thank you!

- CHAUL JHIN KIM (a.k.a. A DESPERATE SOUL)