/ohm/ - electronics general, time, time, time, see what's become of me edition

[Anonymous No.1322757]

old thread: >>1317446

>I'm new to electronics, where to get started?
There are several good books and YouTube channels that are commonly recommended for beginners and those wanting to learn more, many with advanced techniques. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty.

>What books are there?
Beginner:
Getting Started in Electronics Forrest Mims III
Make: Electronics Charles Platt
How to Diagnose & Fix Everything Electronic Michael Jay Geier

Intermediate:
All New Electronics Self-Teaching Guide: Kybett, Boysen
Practical Electronics for Inventors: Paul Scherz and Simon Monk

Advanced:
The Art of Electronics by Paul Horowitz and Winfield Hill

>What YouTube channels are there?
mjlorton
paceworldwide
eevblog
EcProjects
greatscottlab
AfroTechMods
Photonvids
sdgelectronics
TheSignalPathBlog

>What websites feature electronics projects or ideas?
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Where do I get components and lab equipment from?
ladyada.net/library/procure/hobbyist.html
Search the web for "hobbyist electronics sources" to find plenty.
In the US and elsewhere, mouser.com, digikey.com, arrow.com, newark.com are full-line distributors that entertain small orders.

>What circuit sim software do you use?
This mostly comes down to personal preference. These are the most common ones though:
NI Multisim
LTSpice
CircuitLab
iCircuit for Macs
CircuitJS (quick, dirty, interactive)

>What software should I use to layout boards?
Altium
CircuitMaker
Circuit Wizard
ExpressPCB
EAGLE
KiCad

>My circuit doesn't work. Halp?
Check wiring, soldering, part pinouts, and board artwork if applicable, then post schematic. Supply ALL relevant info and component values.when asking a question.
>Li+ batteries
Handle with extreme care, or... https://www.youtube.com/watch?v=gz3hCqjk4yc

[Anonymous No.1322774]

>>1322757
this thread's digits are brought to you in part by the LTC2757 18-bit parallel DAC. it's bretty fast.

[Anonymous No.1322779]

>>1322774
... and by another bretty fast thing, the KSC2757 RF transistor.

[Anonymous No.1322803]

I'm trying to choose an EDA tool to learn for the first time. It seems like there are a lot of equally good choices, so I've just settled on whichever one does curved traces well. I know theyre pointless, but i think theyre beautiful and would like to occasionally use them on personal projects. I know there are some weird github projects that sort of do it, like liquid pcb, but I'd rather learn a proper tool. So which major pcb layout programs have the best support for memey curved traces?

[Anonymous No.1322835]

oh magic conchshell, should i quit my comfy wagecuck job and pursue an electrical engineering degree?
did you guys regret your decision?

[Anonymous No.1322865]

HA take that anyone who doubted
working augmented reality prototype

[Anonymous No.1322866]

>>1322865
Dang, anon. Shit's pretty cool.
I don't know why, but this got me way more excited about AR than I ever was (not very, but that's a lot more than zero).

[Anonymous No.1322887]

>>1322865
Well. That's impressive. Good start.

[Anonymous No.1322924]

First time poster here
I'm in the need of buy/make an audio amplifier for a raspberry pi (first one), you see, I had this old AIO computer that shit the bed, it has a great 1080p screen and built in speakers, those are 5w 8ohm but when connected directly to the PI 3.5 audio jack the volume is low as fuck and I know the speakers can do more than that.
I'm looking at the OP sites and there is plenty of amps and even pre-made amps to buy, but I don't know if I should just buy the "5 watt amps" or should make my own, I have not problem soldering, Im pretty good at that.
Also, someone recommended me to use a PI specific amp because this board can induce noise

[Anonymous No.1322928]

>>1322865
I didn't doubt you could do it, I just thought that it was dumb and pointless

[Anonymous No.1322979]

Can anyone help me identify this component? The front is labeled 04E, under a stylized A. The back is labeled 1210 125M.

[Mr.T !LeoPard6uk No.1322981]

>>1322979

https://www.digikey.de/product-detail/en/allegro-microsystems-llc/A1104EUA-T/A1104EUA-T-ND/1005917

[Anonymous No.1322986]

I was thinking a few years ago about how some games don't work with joysticks and that instead of having one with an actual ADC feeding a USB IC, you could instead have one that PWMs a particular key on a USB keyboard IC instead. So now that I know how PWM works, I was thinking that making this sort of thing wouldn't be even too hard. For a 2-way axis (like pitch or yaw, but not throttle) I'd need to PWM "w" when pitching down and PWM "s" when pitching up, therefore I'd need to make 2 triangle waves, with movable upper and lower boundaries such that I can define the dead-zone and full-on zones. Needless to say, I'd feed these into a comparator, and use that to switch a transistor that fakes a key-press. I can make those voltage rails easily with trimpots and probably buffers and caps to keep the rails stable, but I don't know how I'd produce a triangle (or sawtooth I guess) wave at the full amplitude of between these rails. I could use these rails to power a couple of 555s or comparator-oscillators, but their triangle waves would only be 1/3 or 1/2 or so of the full amplitude they should be, which would mean the top oscillator's V+ would need to be greater than the +5V rail, and the bottom oscillator's V- would need to be lower than the 0V rail. I also don't particularly want to put resistors in series with either leg of the potentiometer, as that will mean I need a bunch of resistors hanging off the board. So, how should I go about getting those triangle waves?

>>1322979
Looks like a hall-effect sensor, but not sure about the numbers.

[Anonymous No.1322987]

>>1322986

[Anonymous No.1322991]

>>1322981
Awesome, thank you. You're quick on the draw.

[Anonymous No.1323006]

>>1322865
nice anon, info on how you did it?

[Anonymous No.1323020]

>>1322986
Why not use a single triangle wave compared to two DC levels - one controlled by each axis?

[Anonymous No.1323024]

any reason i couldn't connect a 32.768k crystal directly up to a schmitt-configurable cpld as a pierce circuit and clock it off that? i can't think of any but i can't find any examples of anyone doing such a thing. presumably because my application is retarded and nobody else needs to.

[Anonymous No.1323032]

>>1323006
Raspberry pi 3 with a small LCD shines through the lens from a cheap VR phone device so it will be in focus. projects onto a piece of plastic at a 45 degree angle from your eye

using raspberry pi camera and opencv to do haar cascade face detection then mirroring the image so it will be the right way in the reflection

Need to compact it and make a housing not held together with packing tape. depending how small I can get it might be a headset or a handheld monocular. once I do that I'll see what other AR/CV stuff I can pull off

[Anonymous No.1323046]

>>1323032
That a TFT or just a regular non-touch screen?

[Anonymous No.1323056]

>>1323046
it is a TFT, non touch

it has a weird problem where it looks like pic related 4/5 times when powered on. No amount of jiggling the connections and ribbon cables affects it once it is on. it just stays like that no matter what.
Then I have to keep cycling the power until it works, not even touching any connections at all, it just randomly works after cycling it a few times. same deal once it is on, no amount of messing with the connections will affect it either way at all. once it is on, it stays like that no matter what
Then sometimes when I turn it on it just stays white and gets extremely hot near the ribbon cable/backlight LED like it is shorting somewhere. just cycling the power will fix it

I havent researched enough to understand what is happening and why it is seemingly not dependent on the connection

[Anonymous No.1323063]

>>1323056
I too have had problems with those Adafruit screens, though for me I simply couldn't use it as a touch screen.

[Anonymous No.1323084]

>>1322981
https://youtu.be/YgHNtzxO0y8

[Anonymous No.1323086]

Are MOSFETs the same shit?


I need to replace some in a HV PSU for cathode tubes, but I cant find a cheap/good source for exact number matching ones.
Old one datasheet: http://pdf.datasheetcatalog.com/datasheet/infineon/1-buz102sl.pdf
New one datasheet:https://www.infineon.com/dgdl/irfz44n.pdf?fileId=5546d462533600a40153563b3575220b

[Anonymous No.1323089]

>>1323086
They're reasonably close, however the new one you're looking at isn't a bit slower and lower rated power dissipation, so if it's running a high frequency might not be acceptable.

[Anonymous No.1323091]

>>1323086
no clue what your 55v fet is doing in the psu but power dissipation in switching fets is a combination of Rds, Qg, and (only for high voltages) Coss. if a replacement fet has lower figures and the same thermals it'll most likely be an acceptable replacement. threshold voltage can also matter but psus generally drive gates with 10v+ so you don't care here. the other anon compared your fets before i could.

[Anonymous No.1323094]

>>1323089
>>1323091
I don't know what they're doing either.
Here's a pic of everything around them.
Big red bit is transformer

If it doesn't work, will it result in a fire? Or just cause flicker or something?

[Anonymous No.1323098]

>>1323094
does it include an off the shelf isolated mains supply? these fets are in a switching configuration (not going to trace it out) so if there is one they may be generating the hv from a 12-24v rail, so the low rated voltage would make sense.

[Anonymous No.1323100]

Doesn't look like it'd be crazy high frequency, I'd go for it. Note you need the IRFZ44NS variant in the D2Pak package.

If the slower switching is an issue it'll likely just result in the MOSFET running hotter and potentially failing again.

[Anonymous No.1323101]

>>1323098
Its in a car. So the voltage comes from an alternator through a rectifier I think?

I've read that all three fets do the same job. A common failure is that one falls off or stops working, and the other two continue on until one dies.

[Anonymous No.1323102]

>>1323100
I can only get that package with prime. I'll have to make it fit.

[Anonymous No.1323103]

I built a flyback converter for experimenting with tubes. It works decently and will give a regulated voltage anywhere between about 40 and 180V. It's based on a boost converter for nixie tubes I found online though I've made modifications. I'm wondering if there's any way to improve it though. Right now it can deliver the full 180V into a 10k load but not much lower than that it starts dropping voltage. I'm only getting 147V into a 5k load and about 68V into a 1k load for instance. I want to get more current. Up to at least 100mA would be nice. That'll require the full voltage to be maintained across a load of 1.8k or less. What changes do I need to make to make this happen?

I'm sure some of these parts are not optimal, especially the transformer but I'm working with parts I had on hand. In a final design I would prefer an off the shelf transformer that I don't have to wind. Recommendations for that and other parts are welcome.

[Anonymous No.1323104]

>>1323102
D2Pak is TO220 chopped with the leads bent down and half the tab chopped off, so should be fine. Make sure you get decent contact with the tab to PCB

[Anonymous No.1323105]

>>1322757
how do you ID the pins of a transistor using just a multimeter? say no datasheet is available.

[Anonymous No.1323109]

>>1323104
Is the pcb contact for thermal transfer? or both thermal and current?
I dont have a hot air blower, so they are not going to get the best contact, but I could always just remote mount them with heat spreaders.

[Anonymous No.1323110]

>>1323103
everybody and their dog is building these fucking things.

your fet and driver look fine so the limiting factor is your transformer. calculate your primary inductance, use (Vin*Dmax)/(L*f) to determine peak current, and then figure out how badly you're saturating your core. i find it's convenient to relate to max energy in a core instead of max flux so if you determine your saturating current (plus margin) with a given turn count you can equate 1/2 L I^2 = Pout and determine what your transformer's output capability will be. there's a few flyback transformers on digikey, and a ton of cores/bobbins that you can wind yourself.

[Anonymous No.1323112]

>>1323110
sorry in the second equation i meant 1/2*L*I^2*f

[Anonymous No.1323114]

>>1323105
A bipolar transistor is made of 2 diodes, base to emitter and base to collector. A diode check will get that for you. From there you can see which way works as a switch, preferably with 3V and medium-high impedance loads so you don't fry the thing. A $15 part tester will also get that for you.

[Anonymous No.1323116]

>>1323114
thanks anon!

[Anonymous No.1323117]

>>1323116
Oh though if it's a FET that won't work.

[Anonymous No.1323143]

>>1323109
For both. If your iron can't handle getting enough heat into the tab, can do it sticking up with middle pin attached to the board where the tab would go, then add a heatsink.

[Anonymous No.1323167]

>>1322835
my magic 8-ball's sources say no

>>1322924
yeah, a lot of devices drive a synthetic ground about halfway between the power supply rails. if your design and your power supply scheme don't account for that, you'll get noise and possibly damage the audio output
build, buy, whichever you feel honestly capable of and comfortable with. imho better to buy for now just so you can hear something. you can always replace it with self-built later

>>1322986
why don't you just the whole thing in software, including the USB HID interface

>>1323056
>garbage
improper or ill-timed start-up sequence?
>hot
sounds like that LCD controller is latching up. be sure all the outputs driving it are low before powering it on

>>1323105
assuming BJT, as other anon said, find the two diodes and you'll have found the base. the B-E junction will measure just a few millivolts higher than the B-C junction
if it's an enhancement-mode MOSFET, there is of course no base and you'll usually find only one diode, the body diode. the third lead will be the gate. you can try shorting the gate to the other two leads to see which one of the diode leads causes the anti-diode direction to drop some voltage, which is the drain.

[Anonymous No.1323169]

>>1323167
>software
But that's not as fun. And since I imagine keyboard controller ICs are a buck a dollar a dozen, it's probably a better way too. I realised I could just limit the actual supply voltage to the pots to Vcc/3, which is probably the easiest option.

[Anonymous No.1323174]

>>1323169
>keyboard controller ICs are a buck a dollar a dozen
yes. they're called microcontrollers and you need to write a USB HID function anyway because they don't come preprogrammed with it

[Anonymous No.1323178]

>>1323174
>microcontrollers
Oh shit, really? Surely the first USB keyboards used a dedicated IC? I'll have to take some apart to see, because if I have to program anything like that I think I'd rather just nab a ready-made one out of a broken keyboard. I guess a wireless one isn't a terrible idea either, but they've probably always been micros.

[Anonymous No.1323186]

>>1323110
not me because I can`t find them in brazil. :(

[Anonymous No.1323196]

How Good are these?

https://www.aliexpress.com/item/Digital-Oscilloscope-DIY-Kit-Parts-with-Case-SMD-Soldered-Electronic-Learning-Set-1MSa-s-0-200KHz/32783300788.html?spm=2114.search0103.3.24.305c225d4WUhYE&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10344_10068_10547_10342_10343_10340_10548_10341_10084_10083_10618_10615_10307_10313_10059_10534_100031_10103_441_10624_442_10623_10622_10621_10620_10142,searchweb201603_40,ppcSwitch_5&algo_expid=c3961768-d51c-493c-b9d8-91dcaf740542-3&algo_pvid=c3961768-d51c-493c-b9d8-91dcaf740542&transAbTest=ae803_4&priceBeautifyAB=1

[Anonymous No.1323201]

>>1323196
>STM32F103
cute
>1MSa/s 0-200KHz
okay if you're only doing audio-frequency stuff and babby-tier digital
not useful for monitoring any serial bus faster than I2C or the usual async

>>1323178
recommended reading: http://www.usb.org/developers/hidpage/HID1_11.pdf
early keyboards may have been mask-programmed. still, the USB HID class is complicated enough on top of USB itself that you probably wouldn't want to be the sucker designing raw logic for the function
if you want fun, check out the V-USB stack, which bit-bangs the I/O port on an AVR to implement the lower layers of the low-speed USB device protocol. a lot of USB-HID prank projects that e.g. toggle caps lock/shift/etc are based on it

[Anonymous No.1323204]

>>1323201
Yeah, just you run out of the mill analog shit with some ampops and 555s. I`ll probably buy a decent probe for it.

[Anonymous No.1323212]

>>1323103
I guess this is part of the old 12V -> 180V/0.1A project. Excellent diagram, found the datasheet for the toroid. What is the URL of the original source and what did you modify? I'm interested in the calculations. With Ct=30pF I arrived at L=14µH and Ipk=3A (ignoring efficiency). Your L is 2.2µH (AL=61nH) and you limit Ipk to 1.3A. I'd like to understand that.

[Anonymous No.1323223]

>>1323196
For that price I would buy it, no matter what.

Also: you do not need to post your personal session data. Anything after .html is not required for the link to work.

[Anonymous No.1323225]

>>1323223
sorry m8. No need to hack me. No bully pls

[Anonymous No.1323241]

>>1323212
The circuit is based on this regular boost converter. Only mods I made was to change the boost topology to flyback, added 10k pot in feedback path to make output voltage adjustable, adjust select component values and change parts based on what I had in my parts drawer, and add the relay and PTC thermistor to quickly drain the output capacitors when power is turned off.

After posting I did wind a new transformer on the same core. It has about 2 more primary windings and probably about 20-30 more secondary. I can pull around 39mA at 180V before the voltage starts dropping so about 7W. Haven't gone through the calculations yet but awhile back though based on what you posted sounds like I need more primary turns.

[Anonymous No.1323244]

>>1323241
Ah, I also increased the output capacitence. I took 2 sets of 470uF 100V caps in series and put those sets in parallel. Added to the 47uF 400V cap I have a total output capacitence of 517uF. Each 100V cap has 90V across them so barely within their ratings. There is a 1A current spike at start up while the caps charge but it drops off once they reach steady state. The PTC does get hotter during discharge now because I'm dumping more energy into it but it seems to survive it okay.

[Anonymous No.1323249]

I unintentionally bought a soldering tip that's too small to accommodate the heating element of my iron.
Will any catastrophic harm come to me if I attempt to drill the hole a bit larger?

[Anonymous No.1323251]

Got alil problem you guys might beable to help with.
When I switch to HDMI or component (y/pb/hr, whatever) mode I can get a picture on my TV. But when I switch to TV mode I get a black screen but with sound. Now when I autotune, the screen is still black even though it should be showing static. I think something on the board must have gone bust. Any explanation as to what could be wrong? Or how much I can expect to get it fixed?

Also sorry I googled but all the results end up about black screen and with sound and not my specific issue

[Anonymous No.1323259]

>>1323241
>0.55ohm Rds(on)
welp there's half your power
you got another one or two of those FETs to add in parallel?

>>1323249
yeah, if you try to hold it in your hand while drilling
it might or might not last as long as in the intended application the iron plating on the outside is very important, but if you're just drilling out the iron plating on the inside, it won't blow up in your hand or anything.

>>1323251
consumer electronics are better on >>>/g/

[Anonymous No.1323262]

>>1323259

>consumer electronics are better on >>>/g/
They're not very practical/technical over there. But thanks

[Anonymous No.1323263]

>>1323259
it's just the interior's diameter is too small, pic related. I'd only be drilling the interior.
I'd need to figure out how to hold it though since I don't have a vice. I'll figure something out.

[Anonymous No.1323264]

>>1323259
>you got another one or two of those FETs to add in parallel?

I do though I'm not sure how many more heatsinks I have.

When I built the circuit according to the original schematic the MOSFET needed to handle the high voltage switching and high voltage MOSFETs tend to have high Rds(on) it was unavoidable. With the transformer doing some of the boosting there shouldn't be such large pulses on the primary side so I should be able to get away with lower voltage MOSFETs. I don't have much on hand but I think I have two IRL3103's that I hopefully haven't blown up already. Rds(on) of 12mOhm.

[Anonymous No.1323265]

>>1323251
have you tried with known working cables?

[Anonymous No.1323279]

>>1323264
>12mohm
those would be beautiful. only other thing I can think to check in the meantime is your transformer, in particular whether it is connected in the right direction, whether winding the primary over the secondary, or adding yet more turns to both windings, might improve coupling

[Anonymous No.1323288]

chinkshit oscilolscope br guy here. I think I`ll buy an arduino uno and directly use the 328 functions for ad conv and other shit so I don`t get crippled by retarded interior designer arduino speak and get fast enough to be a decent scope.

[Anonymous No.1323303]

>>1323288
that's a lot of wrong for just two sentences

[Anonymous No.1323343]

>>1323288
atmega328p adc has a max conversion rate of 76.9ksps (from the data sheet)
Not fast enough to be decent, only slightly better than being blind.

[Anonymous No.1323347]

>>1323241
>Haven't gone through the calculations yet
Do that first, don't fiddle around without valid data. What made you chose Ct=27pF? That's almost off chart for the 34063 and I had to count pixels in the ton/toff diagram to arrive a the values posted earlier.

[Anonymous No.1323369]

>>1323343
Well I think I can get it to 1Mhz if I do stuff right. No idea how to make a computer interface, UIs and shit are dark magic for me. You can make the conversion faster if you use less bits, the default is 10 and I think 8 would be fine for audio resolution. You`d also need to deactivate the digital pins before the AD because that draws power and transient response makes some weird noises that close.

[Anonymous No.1323370]

>>1323369
1Mhz of bandwidth that is. I`ll have to probably have to save stuff on a file and plot on gnuplot but well, life sucks.

[Anonymous No.1323374]

>>1323370
which means NO LESS THAN 2Msps.
nice shitpost tho

[Anonymous No.1323386]

>>1323369
>Well I think I can get it to 1Mhz if I do stuff right.
How exactly? The data sheet says the minimum conversion time is 13 microseconds. That is at the lowest resolution.

[Anonymous No.1323396]

>>1323374
ah, ok then.
>>1323386
the input clock to the ad is between 50Mhz to 200Mhz, I think if you lower the resolution from 10 to something smaller say 8 bits you can increase that clock and speed things a little. But yeah, It`ll need 13 cycles for the conversion.(And 20 something for the first one? I don`t remember much from class) But it`s better than no scope and I can get a nano for cheap near me.

Then it`d be a matter of decoupling the signal from the arduino so it doesn`t get damaged and making some hardware shit for switching the coupling, dc offset and the likes. For the trigger thing I THINK I could use PWM and a low pass filter to get an average value to compare to or a trimmer to set the voltage manually. PWM would allow me to set it using software which would be nice. But I`d have to read that long ass sheet and remember the specific regs they use for the PWM. Then there setting the sweep time and yada yada yada.

[Anonymous No.1323402]

>>1323396
>the input clock to the ad is between 50Mhz to 200Mhz
>I don`t remember much from class
You are off by a factor of 1000
"By default, the successive approximation circuitry requires an input clock frequency between 50kHz and 200kHz to get maximum resolution. If a lower resolution than 10 bits is needed, the input clock frequency to the ADC can be higher than 200kHz to get a higher sample rate."
It isn't going to happen.
>But I`d have to read that long ass sheet and remember the specific regs they use for the PWM.
Good idea, unlearn everything you think you "learned" from tarduino class and stick to the datasheet my dude.

[Anonymous No.1323405]

>>1323396
in any case, the STM32F103 as used on that $20 "DSO Shell" pocketscope is as well-known quantity, easily hackable, and has far faster ADCs. if you don't like the software, no problem, rewrite it

[Anonymous No.1323412]

>>1323402
Oh fuck. See? I had the MC class literally two years ago in the first semester, we used nanos because they were available but we used mostly the low level things. It`s just that I never really used them again and forgot or remember stuff wrong.
>>1323405
Thanks my man

[Anonymous No.1323415]

>>1323412
S'all good bruh. I don't remember shit, I always have my nose buried in datasheets.

[Anonymous No.1323416]

So my tv broke, tracked down a burnt crispy bjt, with a 2N6063 code on it. I looked it up, but couldnt find original bjt. The specs for 6063 seem to be 100v 50a l, but is there anything else i need to consider or can i just slap any 6063 in there? (Or are all 6063s to the same spec?)

Pic related, where bjt blew up. Also its application is switching right?

Electronics nuub pls no bully

[Anonymous No.1323421]

>>1323416
oh, hey, here you are
if you're the anon who had the thread about the Sharp TV not long ago, the part that went in that place is not a 2N6063 because the package is also a part of the JEDEC spec and that is clearly an IPAK package, not a stud mount package
more likely it's an 02N60 FET. like this one https://www.ebay.com/itm/5PCS-SPU02N60C3-MOSFET-N-CH-650V-1-8A-IPAK-02N60-SPU02N60-/192198302385

[Anonymous No.1323424]

>>1323415
>>1323405
I was going to buy one of those right now, but then I remembered I`d have to mess with LCD screens and my toes curled in agony. I think I`ll buy the scope..

[Anonymous No.1323426]

I have a Fender Blues Deluxe Reissue that one day just started sounding.. bad. Normally it's crystal clean and beautiful, but now it always has a hint of distortion.
After noticing it smelled like over heating, I opened it up and found some joints in the power supply to be burnt (circled in red) - The 5W resistors there get very hot (no idea if this was the case before or indicative of whatever the problem is).
Replaced tubes, problem persists.
Checked some voltage points with a multimeter and they seem to be correct.
Where do I go from here?

[Anonymous No.1323439]

Latest WIP: a fully differential audio amplifier
Shitty old car has shitty old head unit/amplifier that is dying. Instead of buying some walmart piece of shit with 5000 LEDs in it I thought I'd have a go at making my own and using the original face/knobs.
I don't want to fuck around with a class D amp and I don't want to fuck around with switchmode power supplies; getting any amount of power out of the meager ~13.8 V the alternator spits out demands running the speaker between two bridged amps, which still only maxes out around 16-20 W per speaker, but that's still plenty loud enough for me and my tiny car. The normal way to bridge amps is to just build two of them and use some op amps to invert the signal going into one and wire the speaker between the two outputs, but then there's the possibility of DC offset and burning up the speaker if the two amps aren't identical and the op amps have anything but zero dc offset. So, the idea is to forgo coupling the speakers with huge expensive capacitors and just build one amp with differential output so that the feedback loop keeps DC at zero between the two outputs. Differential output also has a few nice quirks: The load is put inside the global feedback loop, so even-order harmonic distortion is reduced significantly (according to a TI app note on their differential op amps). I'm using retarded amounts of medium-power transistors on the outputs in parallel because I have literally got bags of them laying around. They should do fine since I'm only working with 14V.

[Anonymous No.1323443]

>>1323439
I doubt simulation means much, but as promised, no 2nd harmonic distortion, 3rd harmonic is already down to -80dB. Not bad! This is with a simulated speaker, too, as in the schematic, not just a resistive load.

[Anonymous No.1323444]

>>1323094
Guys, another stupid question.

If I remove all three Mosfets, and attempt to use the board will it result in fire? Or will the backlight just simply not come on.

[Anonymous No.1323446]

>>1323426
If those resistors are getting hot that means the +/- 15v rails for op amp and other auxiliary circuitry are probably shorted somewhere. It still makes sound because the power amp is working fine, but the inputs and tone controls or whatever it has (i'm not familiar with guitar amps) are all fucked up. If those op amps are seated in sockets, it'd be worth seeing if swapping them out fixes the problem (or fries the fresh chips). Otherwise, search for shorts on the low-voltage side.

[Anonymous No.1323447]

>>1323426
Yeah it's a 5w resistor, it will get hot it's trying to dump 30v at whatever current, it wouldn't be 5w if it could do that and stay cold.
Measuring voltages is a good start really you want a scope to follow the signal see where noise is introduced, check the power is clean(ish)

[Anonymous No.1323448]

>>1323415
gets it. 60-90% of electronics engineering is library science

>>1323426
heat might be normal for that sort of regulator design.
if all of TP41-TP46 are correct, then your problem likely lies elsewhere. my wild-ass guess is that one of the opamps U1-U4 got damaged somehow, possibly due to a power surge or to static. U1 and U4 in particular have sensitive inputs
lacking a scope, you might build a probe like Pic related, connected to a small speaker amp (battery-powered is best). if you replace the speaker with a dummy load, you can use this probe to listen your way along the audio path and try to find where that objectionable edge appears. a 120V waffle iron or similar ~1500W non-PTC heating device makes a surprisingly competent 8 ohm dummy load

>>1323444
only the designer of the device knows for sure and he ain't tellin'

[Anonymous No.1323451]

>>1323447
a handful of op amps, so probably 50-100mA -ish

>>1323443
have you tried randomizing the hFE and resistances to see how well it self-balances vs. component tolerance?

[Anonymous No.1323478]

>>1323451
>have you tried randomizing the hFE and resistances to see how well it self-balances vs. component tolerance?
and after learning a little bit about monte carlo analysis, it's back to the drawing board

[Anonymous No.1323507]

Guys, I need some help identifying these fuckign resistors.

I can't tell which way is which, so either these are 11.0k or 2.2k Basically the resistors are being used to make sure the wires don't send 5v (its a 3.3v shield) to the pins

[Anonymous No.1323568]

>>1323507
If in doubt, just measure it.

Either value is fine.

[Anonymous No.1323591]

>>1323478
alas. one technique to compensate for op amp offset voltages is to put the same impedance on each input. you will occasionally see an inverting amp design that places a resistor between the + input and the reference voltage. that's why

>>1323507
I haven't ever in my life seen a 2% resistor, so it's pretty safe to suppose 220 x 10^1 ±1%

[Anonymous No.1323593]

Hi, new guy to diy here. I'm actually studying to be an EE. But anyway, I was wondering if an easy project to get hands on in electronics would be a computer case fan converted to run on USB A power. Would this be a good project for a novice like me that's all theory and no practical? I've worked with circuits before in digital logic and circuit analysis labs.

[Anonymous No.1323597]

>>1323593
>converted
you're gonna need to give some more detail there, like exactly what sort of circuit you plan on to do that. you might want to read through a lowish-power step-up converter IC's datasheet (the TPS61040 datasheet is good) and see if it all makes sense to you, as step-up converters can be touchy about certain things, like layout.

[Anonymous No.1323614]

>>1323507
Tolerance bands always have a slightly greater gap than the value bands, 11k 2%'s and 1k1 1%

[Anonymous No.1323619]

>>1323614
wat
where in blazes have you seen 2% resistors being sold?

[Anonymous No.1323623]

>>1323288
I own a $20 mini chink scope (DSO138), it's fine for audio stuff and looking at switch bouncing, but it's not good at very low frequency stuff (100ms or longer) or anything higher than 200kHz. It can be a bit of a fiddle getting it to trigger on lower amplitude waves, but maybe some of the trimpots I haven't touched help with that.

>>1323405
>easily hackable
Tell me more...

[Anonymous No.1323636]

>>1323619
Can get them from digikey https://www.digikey.com/products/en/resistors/through-hole-resistors/53?k=&pkeyword=&pv3=4&FV=ffe00035&mnonly=0&ColumnSort=1000011&page=1&quantity=0&ptm=0&fid=0&pageSize=25

Kinda pointless though, 1%s are even slightly cheaper.

[Anonymous No.1323650]

>>1323623
200Khz is the upper limit of the bandwidth according to the manufacturer.

[Anonymous No.1323651]

>>1323597
>TPS61040 datasheet is good
True, it tells you that the chip is unusable because it can only supply about 10% of the current a 12V case fan needs.

[Anonymous No.1323652]

>>1323623
200Khz is the upper limit of the bandwidth according to the manufacturer.
>tell me more
You can reprogram the arm processor, make it in a data logger or some other shit, the manufacturer tells you so in their website.

[Anonymous No.1323666]

>>1323568
Even though I have beige resistors that have ~5% tolerence, should still be fine for keeping pins safe from 5v ruining them?

From what I understand even if you grab 3.3v from arduino board, some boards can still send 5v to digital pins (miso,mosi,ss,sck for example) Sorry if that sounds butchered, its 5 am, and making this reply real quick before I go to work.

[Anonymous No.1323668]

5V on the output - 0.7V drop across the protection diode in your AVR - 3.3V = 1V to drop across the resistor. 1/2k2 = 0.45mA going into the pin. The recommended limit is 1mA continuous for a typical AVR, so you're all good.

[Anonymous No.1323669]

>>1323666
>>1323668

[Anonymous No.1323673]

>>1323623
there's a crapton of community support for the STM32F103 including toolchain walkthroughs etc. and some bretty gud tooling from ST for project skeleton generation and config code writing. see also the famous "bluepill" dev board

>>1323651
150mA from 5V->12V should be just alright
anyway I cited that ds because it's the one I happened to have at hand that was not written in engrish

>>1323636
well, sheeit. looks like they only have 4 bands though so should be easier to tell at which end to start, unlike those 5-banded blue specimens whose start end is not entirely obvious
>beats trying to read the invisible resistance code off an 0402 1% any day

[Anonymous No.1323757]

Hey /ohm/, what stuff should i look into if I want to do analog electronics at ~10Mhz?
I have a 0-100mV signal that I want to amplify and demodulate. I know how I would go about this in the kHz range with opamps but I don't know what considerations I have to make at higher frequencies and how to select the right components. Know any places where I can learn about those things?

[Anonymous No.1323762]

>>1323757
Opamp have ' gain bandwidth product' where you multiply bandwidth by gain so the faster you go the less amplification you will manage. How are you doing the demod? Nothing really special about it if the components can handle it you just have to account for parasitic effects, things that have small impedance like wires and tracks start to have more influence. Pretty much any textbook will help you.

[Anonymous No.1323763]

>>1323762
>How are you doing the demod?
I was thinking precision rectifier + low pass

[Anonymous No.1323773]

>>1323673
>150mA from 5V->12V
Maybe you are confusing switch current (Ipk) and output current (Iout).
Simplified: Iout < Ipk*Vin/(2*Vout) for a boost converter.

[Anonymous No.1323776]

>>1323763
>10MHz precision rectifier
Good luck. Post if you have one, I'm interested.

[Anonymous No.1323781]

>>1323763
you might want to look into the NE612/NE602. things get a bit... different at higher freqs

>>1323773
indeed I was. thanks for the bitchslap

[Anonymous No.1323785]

>>1323776
It is what I would have done on lower frequenciesas I said in >>1323757
I don't realy know what to do at 10Mhz

[Anonymous No.1323794]

What is the Hakko FX-888D of scopes?
~$100-150 but decent quality with everything you could need/want

[Anonymous No.1323806]

>>1323794
>~$100-150 but decent quality with everything you could need/want
"Everything you could need/want" is asking for a lot. That could be a thousand or ten thousand dollars without knowing what you have in mind.
$100-150 is bottom of the barrel for a new scope.
That'll get you a USB oscilliscope from aliexpress or ebay which has no screen which you hook to a computer to see the waveforms.
A decades-old used tektronix usually costs more than that.
So if that's what you want to spend, look for used equipment.

[Anonymous No.1323849]

does anyone know anything about LCD TVs? I have an issue with horizontal lines on my TV appearing occasionally and I've been told it's probably a T-Con board (top board in this pic). Or it could be LCD screen itself it's fucked.

Anyway, what are the boards on the side called in this pic? I know that top is T-Con, middle right is a power board, middle left is main logic board (not sure what the right name is) and I have no idea what boards on left/right are called. They look like LCD drivers maybe? Anyone know?

[Anonymous No.1323907]

>>1323849
remove and re-seat the ribbon cables first. It may be something as simple as the traces not exactly matching up with the ribbons (happened to an LCD display I was working on, and reseating them fixed it)

[Anonymous No.1323909]

>>1323849
Those are inverters. They drive the ccfl bulbs in the backlight.
They can not cause any lines.

[Anonymous No.1323914]

>>1323907
>>1323909
Thanks guys!

[Anonymous No.1324093]

hey guys I bought cc1101 transceivers, and I am able to go to 315mhz on it (according to quick test of spamming signals)

I am trying to figure something out, I am new with radio frequency, and not sure what term this would be, but apparently there is Low,Middle,High frequency or numbers. To get 433mhz I have
>freq0 - 0x62
>freq1 - 0xA7
>freq2 - 0x10

And based on formula it comes out to 433.00000000000 or something like that. Luckily I had the hex saved for 315mhz so I was able to modify the library to have 315mhz as default.

BUT my question is what is the formula, and what can I google to find more about it.

[Anonymous No.1324126]

>>1323794
There's not much useful in that price range IMO. I'd either spend less for a used CRT scope, or go up to the ~$350-450 new entry level digital scopes like the DS1054z or it's competitors.

[Anonymous No.1324155]

>>1323794
>Hakko FX-888D

If you're on a budget, for about 40 bucks right now , weller wlc100 on amazon. I have been using mine only for about 5 months, and love it.

[Anonymous No.1324161]

>>1324155
I have a Hakko and love it.
I'm asking about scopes.

>>1324126
>>1323806
I just don't understand what makes these things so expensive...
What sort of used ones should I be looking at?

[Anonymous No.1324164]

>>1323849
Gee anon, why does your TV give you 5 boards?

[Anonymous No.1324165]

>>1324161
>I just don't understand what makes these things so expensive...
They're kinda niche devices, with some kinda expensive hardware like very fast ADCs, a decent FPGA+CPU, some fast RAM, and a lot of effort in the software development for a product that likely sells in the tens of thousands of units.

For cheap, I'd recommend looking for something like pic related, a bog standard analogue 20MHz dual trace model. Digital doesn't really matter unless you need to capture signals that don't happen often, or need to do accurate measurement. There were hundereds of manufacturers doing similar models, buying used ones made back in the 80s or 90s is fine.

[Anonymous No.1324168]

>>1323446
>>1323448
I guess with nothing to lose I will try just replacing the op amps.
If something else is what killed one of them though and it just happens again, I guess I will not know...

Explain to me more about this probe.
Speaker output of the amp I'm working on goes to the outlet prongs of a waffle iron (for real?...),
and the jack in your picture goes to a different battery powered amplifier,
and I play some constant clean signal at the input of the broken amp,
then touch things along the signal path with the wire?

[Anonymous No.1324174]

I fucking love this circuit. So is it worth making my own mixer out of small PCB-mount transformers or even winding my own transformers, or should I buy a dozen of them somewhere? I imagine the modern ones are pretty damn good, but I can't seem to find ones that will work well with audio frequencies on both inputs, which is what I may well want to end up doing. Not to mention they're $2.50 each and I may well use half of a dozen in the coming year.

[Anonymous No.1324177]

>>1324174
ring modulators are neato.

What sort of frequency range are you looking for?

[Anonymous No.1324200]

>>1323279
No bueno on IRL3103. V(br)dss of 30V. I've made some changes to the circuit and have been experimenting with snubbers but I can't get the ringing on the primary side under about 70V best case and to getting the voltage spikes that low requires a relatively large capacitor and consequently small resistor that burns a lot of power and gets hot as fuck.

I've tried RC, RCD, lossless LC and transformer based snubbers, and well as zener and TVS diodes and more and have burned up a fair number of components. Part of the problem is I don't know the leakage inductance and don't really have a great way to measure it, plus everything is on a breadboard so loads of parasitics are involved. Calculations are basically useless so everything has kinda been trial and error though I have been making rough estimates of leakage inductance based on the 1% rule to get a starting point for RC values.

Right now I'm still using the NTE574 with the high Rds(on). I have another MOSFET that's 100V V(br)dss rated with 25mOhm Rds(on) but I only have one and in testing I'm occasionally getting ringing above 100V so I'm not using it. 2SK3216 I think.

[Anonymous No.1324202]

>>1324200
*NTE2900 or IRF634

NTE574 is the output diode. Not the FET.

[Anonymous No.1324210]

>>1324174
>ring modulator

eww. I hate these things. I could never get mine to work plus I hate winding transformers. NE602 is a cheaper and easier option for a mixer though any line level audio going in will have to be attenuated. Max input level is -25dBm which is 68mV into the 1.5k input impedance of the NE602. You could use a passive attenuator but for continuously varying signal levels like with audio a VCA might be better.

I've also been experimenting with pentagrid tubes which seem promising. I'm not used to tube circuit design so my first couple of designs haven't been that great but I'm figuring things out slowly but surely.

[Anonymous No.1324219]

>>1324210
That's the coil I used idk where the other one is but it was identical. No idea why it didn't work. It was low inductance, so low my shitty component tester couldn't even measure it and I was testing with low frequency signals probably 100kHz LO 1Vpp and 1 or 10kHz test signal 2Vpp, whatever the case impedance wasn't really a problem. Diodes were general purpose small signal 1N914 or 1N4148.

[Anonymous No.1324225]

>>1324177
Mainly audio (100Hz to 5kHz or so) which I guess requires higher inductance coils. I definitely want to get into radio stuff sooner or later, but for now I'll stick to audio.

>>1324210
I know it says "OSCILLATOR" here, but can I feed any old low output-impedance audio signal into there and expect it to work? Also why are there two inputs and outputs?

>>1324219
Looks like you've wound it far too coarsely, but then again I've never dealt with MHz. What was your estimated w*L impedance for your RF frequency?

[Anonymous No.1324232]

>>1324225
You don't feed your signals into the oscillator pins. The NE602/SA602 is capable of generating the local oscillator (your carrier) by itself using that internal transistor there. Adding external capacitors and inductors in colpitts or hartley configurations or crystals in fundamental or overtone mode will allow you to use the chip to generate the carrier for you. The internal oscillator works up to 200MHz. You can also feed in an external carrier to pin 6 directly and leave pin 7 unconnected.

Audio goes in pin 1 or 2. Output is pin 4 or 5. The reason there are two outputs is because the IC is a double balanced mixer. If you are feeding in balanced audio you will use both connections. Since you probably aren't you can use it single ended by using one of the two inputs and outputs, doesn't matter which you pick. Leave the other one unconnected or bypass it to ground with a capacitor. DO NOT simply short it to ground. These pins are internally DC biased and shorting them to ground will make things get hot fast. It's worth noting because of the DC bias on the inputs and outputs all your signals into and out of the IC should be AC coupled as well.

[Anonymous No.1324239]

>>1324232
I don't want to use a carrier, I want to see if I can use it as a mixer for two audio-frequency signals. I'll keep note of the shorting tip, but I'd probably look at the equivalent circuit before using and hopefully figure that out.

[Anonymous No.1324245]

>>1324239
AD633 looks like it'd do what you want without needing transformers.

[Anonymous No.1324246]

I want to charge laptop with 5V2A phone charger. Laptop takes 16V.

There are cheap constant current DC DC boost converter on ali that I could use.

What really happens with laptop when much lower than required current is supplied? Phones doesn't care about it but I've never done that with laptop before.

Will it still charge battery (don't care how slowly) while laptop is turned off? What happens when it's turned on and requires more current than 5V2A can supply, will it pull difference from battery or just go berserk?

[Anonymous No.1324249]

>>1324239
>I want to see if I can use it as a mixer for two audio-frequency signals

Uh, yeah it should work. Not sure why you'd want to but there's no reason you can't use an audio signal for the oscillator I guess. Just leave pin 7 unconnected and connect your audio source to pin 6 through a large capacitor that presents a low impedance for audio frequency signals. Connect your other audio source to pin 1 or 2, again through a capacitor like above and take your output from pin 4 or 5. Audio on the oscillator pin should be above 200mVpp and audio on one of the input pins needs to be below -25dBm for proper mixing.

All that said are you sure you want a frequency mixer? This is usually used for RF stuff, modulators/demodulators, etc. By mixing do you mean adding two audio signals together to do something like mix stereo audio down to mono? You wouldn't use a circuit like this for that purpose. For that you'd want a summing amplifier. Hell you can do it with two resistors at the expense of some signal amplitude.

[Anonymous No.1324250]

>>1323781
>look into the NE612/NE602
Thanks for the reminder. Listen >>1323785, the best AM Demodulators are double-balanced mixers when you feed the input signal to both inputs, essentially squaring the signal. Get the appnote AN531 and look for 'AM Detector'. It's about the MC1496 but the principle can be applied to the NE612 as well (pic).

[Anonymous No.1324269]

>>1324161
My bad, anon. When I saw Hakko I assumed soldering station.

[Anonymous No.1324272]

>>1324246
What happens will depend on how your boost converter deals with an overload, if it smoothly goes into current limit mode it might work properly, if it shuts off or worse doesn't limit and just overheats and catches fire, no.

[Anonymous No.1324275]

>>1324093
see p57 of the datasheet, register 0xD description

>>1324168
>explain to me more about this probe
you pretty much got it, anon. use your ear to find the objectionable distortion as you probe thru the signal path
>waffle iron
yes, for real. a small electric room heater, any dumb heating appliance on the order of 1500W/120V. turn it up to maximum and check that you measure a resistance not far from 5-10 ohms across it

>>1324200
>parasitics
well, one rule you definitely do want to follow in switching power supply design is to keep your high-frequency nets short, sweet and to the point. don't even bother routing those through the breadboard. tack 'em together ugly style in the air using the shortest leads and use a shorter, fatter piece of metal as a bus bar for your high dI/dt paths. I'm a bit surprised that a high-current Schottky across the primary didn't work out, did you check to see whether connecting one of the windings the other way round helped? I'm thinking you could be tapping the inductive spike instead of the pulse, thus the poor load regulation
also I think you want a lot more turns

>>1324225
Craig Anderton's _Electronic Projects for Musicians_ included a ring modulator circuit based on some long-obsolete FM demodulator chip, so it certainly can be done

>>1324246
>I want to charge laptop with 5V2A phone charger. Laptop takes 16V.
oh sweetie.jpg

[Anonymous No.1324285]

>>1324272

voltage booster is constant current so you can set maximum draw on the boosted side.

[Anonymous No.1324287]

Hey. I know little about electronics but would like to make some research to help my 90 year old grandmother.

How would one go about repurposing a portable headphone amp as a "tele-coil"/audio induction loop transmitter for hearing aids? She has a purpose-designed device for this but it's shit quality and the price of repair and replacement is straight up criminal.

[Anonymous No.1324291]

>>1324287
the interwebs contain many simple DIY resources on this task. in short, just get enough wire to match the output impedance of the amp and wind it all in one direction
you could prove the concept by removing the magnet from a small headphone-type speaker element and placing the coil near the hearing aid while driven by the amp with an audio signal

[Anonymous No.1324292]

>>1324285
Should kinda work then assuming the laptop has been designed to watch for voltage drop. Set current limit on the boost to get rated current on its input

[Anonymous No.1324293]

>>1324287
First, calculate your current and voltage requirements for the size of room you're covering and size of wire, that'll tell you the current and voltages required. A headphone amp probably isn't going to be good enough.

[Anonymous No.1324294]

>>1324293
http://signet-ac.co.uk/manuals/Signet%20Loop%20Calculator%20V1.3.xls

[Anonymous No.1324295]

>>1324293
>>1324291
I want to make a neck loop which the amp would hang from rather than cover a room. This is the sort of setup she wears right now.

That means I'd need some exotic kind of wire right?

[Anonymous No.1324301]

>>1324295
The wire wouldn't need to be anything particularly special, but you'd need to do quite a few turns to get sensible impedance for a headphone amp.

[Anonymous No.1324303]

>>1324301
Alright. Thanks anon.

[Anonymous No.1324378]

>>1324295
34AWG copper is specified at ~265 mohm/ft at room temperature. figure 15ft = 4ohm so 120ft to get near 32ohms. that's probably about 40 turns for a neck yoke. be advised that wire this thin is not really recommended for repeated bending or physical strain and won't do well to just hang out there unprotected. one thing to try is winding a coil of it on a long mandrel and putting it inside some sort of long fabric tube with cushioning and/or support

[Anonymous No.1324402]

i need to make an otg cable to interface nolo vr to the oculus go when it comes out. i'm wanting to make something that looks semi-professional but am wondering if shit from ali would be good enough quality
>this will be the first project i do since summer camps as a kiddo

https://www.aliexpress.com/item/OOTDTY-10-Sets5-Pin-Right-Angle-Micro-USB-Connector-Male-Plug-Kit-with-Black-Cover-Solder/32842537408.html
https://www.aliexpress.com/item/10pcs-Micro-5P-USB-Male-Welding-Wire-Single-Plug-5-pin-5PIN-Connector-Adapter-DIY-Kits/32821916799.html

[Anonymous No.1324420]

Hi. I don't understand a lot about electronics. This circuit used to be a 12v .5 A DC out wall wart for cigarette lighters. I'm trying to boost the output amperage. Will replacing the resistor in the circuit with one of lower resistance accomplish that without burning down the building?

[Anonymous No.1324433]

>>1324420
>Will replacing the resistor in the circuit with one of lower resistance accomplish that
no

[Anonymous No.1324463]

Want to get into DIY, got what I think is a pretty typical project in mind - a handheld game console. Got a stupid question before I spend lots of money on this stuff.

I'm looking at using some board that can more or less handle PSP emulation, and I want to use a 5-6 inch screen with at least the resolution of a PS Vita (960x540 or anything higher works). Looking at Pi3, bananas, rock64, tinkerboard and - that thing is looking so cool - up core. I definitely don't want to use the certified Pi screens or Adafruit displays, they're either too big, too small or too low-res. What options do I have, and what options do I have if I want a touchscreen as well?

From more or less realistic options I see Manga Screen 2, but it's not in stock (if it's even out) and it would take up HDMI/USB ports. There are some chinese driver kits that convert HDMI to MIPI, but they cost 50 bucks and I'm not sure if they support touchscreen - and again, taking up ports. But I can live without having a free HDMI if everything else works fine, just not sure that it will.

Then there's what I would see as an ideal option, just directly plug a MIPI/DSI screen from a random chinese supplier on ali or globalsources. But I know that Pi only supports its own MIPI screen, so does Pine/Rock, and I have no idea whatsoever whether tinkerboard or Up would work with any random MIPI screen - how compatible are these things with generic smartphone-like displays, and is there a board known to work with at least some of those?

Also, do I understand correctly that the touchscreen functions via an i2c connection in the MIPI itself, so as long as it's otherwise compatible I shouldn't have to worry about connecting it to the separate i2c on the board or anything?

[Anonymous No.1324480]

>>1323421
ty senpai, upon further inspection im reading "02N60C3"

I found the exact one.

Pic related, shows where FET got burned.
So do you think i probably need to just replace that FET and this 200v 33uF capacitor with the same value?

[Anonymous No.1324484]

>>1324420
no, the transformer needs to be upgraded
you'll need to buy something bigger

>>1324463
typical but not beginner-tier project.
dealing with MIPI requires some experience working with low-level video programming and driver development. a 1GHz scope wouldn't hurt either. without all that, you might be stuck with proven solutions

>>1324480
worth trying. but, properly, you should probably also have a look and a probe at the circuitry around it. I can see D7215D and Q7201D that could be related and possibly damaged due to Q7202D's gone splodey, and who knows what SMD components on the solder side that could also have potentially failed. at least if you buy 5 you can try the simple thing and have some left over if it pops again
be sure you clean the hell out of that part of the board with acetone and IPA. carbon is, after all, conductive

[Anonymous No.1324515]

>>1324484
I see, thanks, so going full MIPI is better left for another time. Either way the console won't be my very first project so I hope to get some experience along the way.

I just wonder whether for now I can get touchscreen to work with any of said proven solutions, the HDMI converters look nice but there is no information whether touch works with those...

[Anonymous No.1324540]

>>1324484
Ok, so i desoldered the cap, read 45 uF,
then checked the diode(while soldered) im reading .45 volts one way, 0 the other, and its the same as the other 3 diodes at that point.

I attempted checking the mosfet, it's a bit confusing. I wasn't able to get a reading of any volts on the diode test for the fet. ill just order one

[Anonymous No.1324543]

>>1324540
i ordered these

howdidido.png

[Anonymous No.1324566]

>>1324246
>just go berserk?
It'll go to hiccup mode.

Builtin power supply is turned off when voltage drops to a certain point and enabled again at higher voltage.

Since your PSU is merely 10W it's way-way less than a laptop requires. Once laptop starts to pull current input voltage will droop and laptop PSU will stop pulling current. Your 10W will recover and then the cycle will be repeated.

Generally laptop's will work with lower wattage PSU but not that low (unless you have a net book or something),

[Anonymous No.1324570]

>>1324480
PCB for Q7202D is burned to ashes, you have to clean it thoroughly and remove burned material as it's likely conductive (yes you have to use exacto knife or something along these lines and scrape the PCB until it's clean)

[Anonymous No.1324573]

Will someone please explain how an alarm is supposed to be wired on this PID? Thanks

[Anonymous No.1324592]

>>1324573
pin 11 & 12 are open with no alarm, closed during alarm.
maximum is 250v @3A resistive, you have to supply the power it's just a relay.
are you sure you should be playing with this? show us what you are doing if you want a help

[Anonymous No.1324604]

>>1324592
I have a fair amount of hobbyist experience with electronics, but I still struggle with simple concepts from time to time. The PID has power (110v) coming in at 9 and 10. I'm using the SSR output with a K-type thermocouple and otherwise everything works fine.

I had assumed I would be able to bypass having a relay for the alarm if the alarm was a resistive load and the alarm's power requirements were similar or less than the alarm output. This does not seem to be the case. When I have an alarm signal on the display screen I still get little or not output from the PID at 11 and 12 (>.02 VAC). It may even just be error in my meter. Thoughts?

[Anonymous No.1324626]

>>1324604
Figured it out. I assumed the alarm output created an output to drive a relay, not realizing the alarm pins themselves were the relay. Is the diagram above a normal way to depict that in electronic schematics?

[Anonymous No.1324648]

>>1324245
Looks pretty nice, but slightly more expensive. Maybe I'll buy a couple of both and see what gives me good results, I'm bound to use them all anyway.

[Anonymous No.1324654]

>>1323086
Guys, I got the FETs.
I swapped them out, then tested them using this guide:
https://www.utm.edu/staff/leeb/mostest.htm

Testing the ones I removed, they work, but when they should be open, they are actually reading voltage, at 2.5V or so. the new ones test and just give me OL on my meter.

I also lifted the legs on another FET the same as the three I pulled off. it tests like the new ones, giving OL when discharged.
Does this mean that this was my problem?

[Anonymous No.1324665]

>>1324239
The complete kit is about $6, Xicon 42TM018 x2, 1N34A x4 plus PCB. The 'carrier' is your output, just like in your simulation. Nothing beats a passive ring modulator.

[Anonymous No.1324670]

>>1324246
>5V2A phone charger
10 watts - how many watts is your laptop?
5v > 16v @ 90% efficiency = 16V 0.56A

[Anonymous No.1324717]

Hey /ohm/, beginner hobbyist with breathy LED-design from last thread here again.

As usual for my projects, this has started to get out of hands fast. I got fed up just simulating stuff in LTSpice, so I decided to dabble a little bit on PCB-design. Downloaded KiCad, watched through Getting to Blinky 4.0 by Contextual Electronics and went to town. Gonna run this through electronics department prof and see if I could get couple printed. Does it look like something I shouldnt be too much ashamed to show? Its 2-side board with front being Vcc-plane and ground-plane on bottom, all components beign trough-hole for easier soldering.

Dont mind about resistor and cap values in the schema, those are the placeholder values I got by playing with 5v simulation without additional LEDs in the circuit. I propably end up using either 1 or 2 3v coin cells. I'll play around with it when I have validated on breadboard that this thing even works, and then when I have decided on the actual LEDs im gonna put on the finished product.

Also, it took me a week to realise that I might need multimeter to do anything at home. Im so used to have one on my toolbox at work that I can borrow when needed, that would be kinda hard now that im student instead of working full-time. I could go to say hi and ask to borrow one but meh, its easier to have one of my own. Went with 50€ Tenma 72-7780, seemed like good enough piece for my needs.

[Anonymous No.1324732]

>>1324543
jesus fuck that char looks bad. is there even any copper left there?
also, blowing your nose by C7203B is a nice touch and will aid the subsequent solder job almost as well as a shot of black
to quick-and-dirty verify MOSFET action you want to read ohms from source to drain with gate to drain open then shorted. this might not work if Vgs(th) is higher than the ohmmeter's open circuit voltage.

>>1324543
you probably should have ordered 2 just in case there's a yet undiagnosed fault. at least digi-key doesn't gouge hard for shipping.
youdonedidgoodson.jpg

>>1324626
yep, perfectly normal. if you were intended to provide the relay it would be drawn outside of the box

>>1324717
SMD isn't as hard as all that. get some tacky paste flux and you'll be fine. 1206s are piss-easy to solder. you should consider, just for giggles, to add some 1206 components and footprints in parallel to and under your THT resistors, and you'll have a practice board too
THT aside, this board's kinda big. why not 1/4 or 1/8 watt resistors? it's not like they'll even see that much in this circuit
consider the capacity of the button battery is probably not more than 50mAh. then consider the current consumption of all your LEDs and the timer, figure out how long it's going to run, and then consider a AAA battery on- or off-board for power
my personal autism wants to see R4 in a row with R3 and R5
D2 might be closer to the board edge than necessary, ditto the add'l LED Vouts (also we don't call it Vin, it's +Vout and -Vout since it's not an input per se)
generally, in production, it's a good idea to minimize the number of distinct parts/values you're using. you should make both NPNs the same type
a circuit like this "should" be able to fit on a single-sided board. since fabrication costs increase with layers, maybe you could try to route everything on one side. it's no sin to throw a wire jumper or two in there if truly needed
bretty gud first attempt, just tighten it up :DD

[Anonymous No.1324770]

>>1324717
a few more thoughts:
the cost of manufacturing a board falls within a broad range, but usually on the order of €0.1/cm^2/piece. check out pcbshopper .com to get an idea of manufacturing cost. good idea to get a couple or few extras, sometimes this pushes the price per board down
another benefit of reducing your board to single-side is easier and cheaper manufacturing. your EE department may have a low-tech fabrication lab consisting of little more than a few trays, a drill press, a light table, a dark room, and the necessary chemicals and supplies. thus, in just an hour or two, you can go from layout to boards in hand. plated through-holes are considered high-tech and are not easy to fabricate in small quantities. without plated through-holes, you will need to solder both sides of some components, which may be impractical with sockets/connectors or the battery holder. you would also probably want to fatten the traces, as low-tech methods are much more reliable when all features or spaces are 16mil or larger
if you do get the board done professionally and double-sided, consider putting your battery holder on the "solder" side of the board to make better use of real estate
and remember, we're only brutal because we <3 you

[Anonymous No.1324871]

Just fuck my shit up senpai. I just realized this after creating the board. How do I fix this bullshit?

They're 74HC595 shift registers and ULN2803 transistor array to drive a nixie tube.

[Anonymous No.1324882]

>>1324871
"untwist" those 7 signals and swap the bit order in software
OR
route the traces under and through the sides of the chip(s), or between pins if possible.

[Anonymous No.1324897]

>>1324882
Well, fuck me, you're right, I could've just reversed the pin order in the schematic since it doesn't matters in which order I connect the transistor array. Fuck I'm stupid! I spent 30 minutes routing all the traces in between the pins. Now erase everything and start again.

[Anonymous No.1325015]

>>1324897
Looks like it'd be easier with U1 the other way around.

With all the super cheap chinese PCB houses doing single sided boards isn't really worth the bother IMO.

[Anonymous No.1325033]

>>1325015
spotted the non-autist with no impulse control problems and no 10 ft^2 of copper clad innabox somewhere

[Anonymous No.1325088]

What item of consumer electronics is best value if you want to buy it to harvest parts? I know it will probably never be worth doing, but as something to watch out for when checking out roadsides and garage sales.

[Anonymous No.1325113]

>>1324654
Guys it works.
Kind of sort of.

It seems like it isn't lighting up one of the tubes all the way, and the others are dim.
It also started smoking after 5 minutes of it being on, but it eventually stopped smoking. I drove around for 30 minutes or so and it stayed on the whole time. Not blowing the fuse like it used to.

I really don't care about its current sad state, but I am going to convert it to LED at some point maybe.

[Anonymous No.1325124]

>>1323781
>look into the NE612/NE602
Thanks. I even found a circuit that does what I want with slight modifications in a Spice simulation.
One thing I don't quite undestand yet is how big inputs it can handle.

[Anonymous No.1325132]

>>1324732
>>1324770
Thanks for the input, love all the help I get as im in totally new area for me and going without a guide.

I started do put together a board with SMD-components. Also trying to do it 1-sided. This is really relaxing way to spend your evenings, at least with board this simple. I can imagine its gonna be lot less fun when talking about big boards with metric ton of parts.

On the battery side, the problem is that I need to fit everything inside a pretty small plastic model so im not sure if Im able to fit even AAAs there. Gonna go and get the model later today so I can start to get some measurements. I think the best case scenario is that Im able to fit 9v battery there with easily done magnetized "lid" so I can change it too.

Also realised that I dont have any kind of swich on my schemas. Gotta put that there somewhere between battery+ and Vcc-plane. Outboard 9v/AAA-box would make that pretty easy.

I come from /tg/s Work in Progress-threads where I get some good, straight critique on my models, you are far from brutal with your comments <3

[Anonymous No.1325139]

>>1325124
>how big inputs it can handle
Less than 100mV I guess. Also consider the MC1496 mentioned at >>1324250 which works well at 10MHz. One OM from .cz made a simple AM radio using the NE612. Final version at http://599.cz/view.php?cisloclanku=2014092201 (Translate this page).

[Anonymous No.1325206]

>>1325015
i don't know about him but i make such a habit of not routing anything on the bottom until i have to that some of my boards end up single sided by coincidence.

[Anonymous No.1325248]

>>1325132
>relaxing
this. the swearing comes in proportion to density, but even then layout is mostly a quite pleasant pastime. you just keep iterating on sections until it all fits and meets whatever other criteria. they say in layout, "if it looks good it'll probably work good"
>9V
the trouble with that is you start to burn a lot of power, either in voltage dropper resistors on LEDs or in voltage regulators. you might consider putting LEDs in series if you go for a higher supply voltage. fortunately forward voltage is inversely proportional to wavelength, so in order to make better use of a 9V supply, 4 red LEDs can be connected in series to share a single dropper resistor (say 470 ohm)
for the flashing LED you might want to consider series-connecting a number of LEDs, or consider a PWM by a second 7555.
still, it's going to take a bit of engineering to keep this running for a whole weekend on one 9V battery. pussying out and going microcontroller is the easiest way to achieve that sort of power efficiency and size

>>1325206
gets it
>bonus: free and rock-solid ground plane

[Anonymous No.1325281]

>>1325248
>inversely proportional to wavelength
Not a continuous function. Diagrams from Nichia data sheets.

[Anonymous No.1325284]

Is a capacitor not draining the fault of its respective resistor or is it the cap itself?

[Anonymous No.1325305]

>>1325284
Maybe you could post a drawing explaining what you mean.

[Anonymous No.1325307]

I got this soldering station for free, and the tip is a fucking wire. Am I safe to use it? Looks like it hasn't been used in 50 years.

[Anonymous No.1325318]

>>1325307
station? where's the temp control?
also, almost certainly NOT ESD-safe

[Anonymous No.1325325]

>>1325015
>Disdainforplebs.jpg
One single board, one 0 ohm resistor, 9̶0̶0̶0̶ ̶h̶o̶u̶r̶s̶.

[Anonymous No.1325329]

>want a pcb designer for throwing together pads and traces quickly without a fucking schematic or netlist
>find "pcb artist", works great
>go to export gerber files
>no option
>can literally only order pcbs through the company that distributes the software
into the trash it goes

[Anonymous No.1325336]

>>1325307
That's the temp control in the background. It has no real temperatures listed just numbers from 1-4

[Anonymous No.1325344]

>>1325329
>not using inkscape

[Anonymous No.1325346]

>>1325344
from a quick google it seems that i'd need additional software to convert the pdf or svg or whatever into gerbers, and the point at which this becomes a new toolchain is the same point at which i'd rather just make this shit in altium with all its bloat.

[Anonymous No.1325369]

>>1325336
Looks quite modern, try if it works.

[Anonymous No.1325370]

>>1325325
looks good man

[Anonymous No.1325381]

>>1325325
I don't necessarily love pin 14's lack of clearance. give it another 1~~000~~ hours but otherwise berry gud

>>1325346
nice design rule checking

[Anonymous No.1325409]

>>1322757
Are synthesizer geeks the cucks of all hardware engineers?

[Anonymous No.1325411]

>>1325329
Easyeda , you tard.

[Mr.T !LeoPard6uk No.1325437]

>>1324219
You wound the transformer wrong.
1st, changing winding direction from CW to CCW effectively changes "start" and "end" leads.
2nd, you should wind it trifial (either twist three wires together or just wound using three wires in parallel).
3rd, it looks like for 100kHz you have too low magnetizing inductance (use thinner wires and put more turns).

[Mr.T !LeoPard6uk No.1325442]

>>1324219
>was testing with low frequency signals probably 100kHz LO 1Vpp and 1 or 10kHz test signal 2Vpp, whatever the case impedance wasn't really a problem.
It wouldn't work with voltages like that, you need like p-p 1V (feeding through a series resister) as a LO so it commutates the diodes and your test signal must be lower than that (so test signal doesn't commutate the diodes), like 100mV.

[Anonymous No.1325466]

>>1325411
>web interface
NOPE

[Anonymous No.1325468]

Maybe I should drill the holes in my PCB before drawing the traces and etching it, so I can make up for any misalignments...

[Anonymous No.1325473]

>>1325468
>not using a cross-slide vise on your drill press
understandable, because it's $50, but solves the alignment problem neatly
>through-hole
dubious

>>1325466
>can't draw a schematic in two minutes
>through-hole
lmaoing at your life

[Anonymous No.1325474]

>>1325409
that's a bit of a strong term, isn't it? "engineers"

[Anonymous No.1325485]

>>1325473
Hey I make PCBs designed with GIMP with magic marker and a 1mm drill bit, and I'm not going to stop doing so unless I absolutely need a compact SMD board or components that don't come in through-hole. I prefer using boards with nice thick traces and obscure metal-can transistors, and I'd be using CDIPs and those epoxy-blob single-inline-packages if I could find any. Not to mention I can use IC sockets to replace any broken ICs I have without busting out the iron.

[Anonymous No.1325486]

>>1325485

[Anonymous No.1325507]

im making a heinously bright led panel. they are 100w 32-36v 3 amp cobs wired up 6 in series and 3 banks in parallel. i plan on running it off the wall and 125vac rectified gives about 175vdc, so each cob is getting about 29v (undervolted for thermal management) and the whole thing draws around 9 amps.
as i found out, as these things heat up the current draw increases and leads to thermal runaway which aint no good. what is the best way to keep them under control?
hard mode: no chips or controllers, only passives if at all possible

[Anonymous No.1325512]

>>1325507
You could make a simple constant current LED driver only using a capacitor and a bridge rectifier.
Just have the capacitor on the AC side of the rectifier. to choose the capacitor, find the nominal voltage drop across the LED array, and choose a capacitive reactance that will have enough voltage drop across it to give the right voltage across you LED array.

[Anonymous No.1325533]

>>1325512
so basically what youre saying is that for example, if one row was like 10 ohms, you would look for a 30 ohm cap which at 60hz would be about 65uf right? and this will prevent the array from pulling more than 9-10 amps? will post rectifier filtering affect this at all?

[Anonymous No.1325535]

>>1325507
PTCs, maybe

[Anonymous No.1325545]

>>1325507
>>1325535
Anything resistive will make a bunch of heat, that is unless you can get a low-resistance high temperature coefficient current-limiting shunt of some sort. About the only other method that doesn't require an IC would be a capacitive dropper like >>1325512 suggests, but that requires it to run off AC in the first place, which probably means some fairly beefy output caps if you're pulling over 250W.

If you've already spent that much on all those LEDs, the last think you want is to run them off a shitty PSU. Buy or make a switching CC PSU, you'll regret not doing so. So do you plan on running it off mains or a battery? If mains you'll need those filter caps anyway, but a capacitive dropper still isn't that ideal, and may even waste more power than a switching PSU. Since the total voltage needs to be 174, I assume you're running off 240VAC not 120?

[Anonymous No.1325560]

>>1325442
>resister
your not only a tripfag, but a fellow eurofag?

[Anonymous No.1325562]

>>1324420
The voltage rating is the output voltage, but the current rating is not the output current. It is the maximum amount of current that it can handle without smoking.

[Anonymous No.1325565]

>>1325562
>without smoking
But isn't that what a cigarette lighter is made for?

[Anonymous No.1325610]

>>1325533
This is all nonsense. If you have 175V peak voltage after the (200V 10A) bridge rectifier and you need 180V (30V per LED module) there's no headroom left for current limiting. Let the fuse do that.. Brightness will be far less than expected but you can use your contraption as a line voltage indicator. Did you merely glue the modules to a steel plate? If so you have no heat sink to speak of. Be sure to ground it and touch it a minute after 'first light'. Good luck.

[Anonymous No.1325629]

>>1324232
Did you notice the fatal error in the diagram you posted?

[Anonymous No.1325631]

>>1325442
>>1325437
Feel free to kill yourself at ant time tripcunt.

[Anonymous No.1325632]

>>1325442 #
>>1325437 #
Feel free to kill yourself at any time tripcunt

[Anonymous No.1325638]

>>1325442
>>1325437
Feel free to kill yourself at any time tripcunt

[Anonymous No.1325646]

>>1325610
>If you have 175V peak voltage after the (200V 10A) bridge rectifier and you need 180V (30V per LED module) there's no headroom left for current limiting.
the stated spec is 32-36v (and required for full output) but the actual vf is closer to +/- 24v so they can be underdriven by a bit so 28 or 29v will still make them plenty bright and still be somewhere around 80-85w id guesstimate
>Let the fuse do that.
why would i want to keep replacing a fuse every 5-10 minutes? thats retarded. the whole problem im facing is increasing current draw as they heat up so a fuse absolutely will not solve the problem.
>Brightness will be far less than expected
as above the actual vf is far lower than the spec and they still put out an incredible amount of light at just under 30v
>you can use your contraption as a line voltage indicator.
i... why?
>Did you merely glue the modules to a steel plate?
of course not its an aluminum heatsink and i used thermal adhesive. im an idiot not a retard.

pic related has been its power source for testing and like i said it works fine except the chips heat up then draw more current and eventually can start to burn the phosphor because they get so hot so current limiting is a requirement if i want these things to last more than 30 minutes (and like i said theyre thermally glued on so it would be a huge pain in the ass to remove them)

[Anonymous No.1325686]

So, here is my current try at doing SMD-board out of my breathing LED. Got it down to 56mm x 20mm. Bought the model im gonna light up and measured everything up, with some cutting I get 8cm x 2cm x 2cm area for my PCB to sit on, with nice little access door for on/off-swich. I also managed to fit 4xAAA-battery holder in there, so I guess voltage im gonna use is 6V.

LTSpice is telling me that my whole board with 4+1 LEDs takes little over 100mA on average. That translates to something like 8 hours of battery life with alkaline AAAs. And LTs version of 555 is ideal so I believe there is going to be some more current going through the circuit in real life. Im gonna test this on breadboard before burying it, but I started to look at microcontrollers as an alternative.

Now I only need to learn how uCs work, find one that fits my needs, hope that I can program it with arduino and make circuit around it.

[Anonymous No.1325690]

>>1325646
Ok, understood. Did you try to run it without the storage capacitor after the rectifier? That should decrease the average current because the conduction angle per cycle becomes smaller. If that prevents overheating you could use a smaller value to find the right current.

[Anonymous No.1325695]

>>1325690
no because i didnt want to risk the pulsed dc somehow damaging the cobs

[Anonymous No.1325700]

>>1325565
("""optional""") add-on component

>>1325686
a few connections missing but otherwise pretty good
there's still a bit of power consumption that can be squeezed out of that design. 20mA is bright for an LED. you should obtain the LEDs you intend to use and check their brightness under lower currents. also, did you try Pic related? with 6V or even 5V supply, you could easily put 2 in series under one dropper resistor. viola, current consumption cut almost in half
>not using SOT-23 transistors to decrease height of board
there are MMBT3904 etc. types for some of the common JEDEC 2N types if you want to try that
>smolduino
start here, PWM example at the end http://tronixstuff.com/2011/11/23/using-an-attiny-as-an-arduino/

>>1325695
>pulsed dc
this is literally how most LED dimmers regulate brightness
just make sure the peak current and average current are within the LEDs' ratings

[Anonymous No.1325701]

>>1325700
i figured 100-400khz wouldnt be damaging because its so fast vs 60hz. also the microflashing that would ensue would probably drive me nuts

[Anonymous No.1325703]

>>1325701
wouldn't it be 120Hz due to the full-wave bridge? that should be less objectionable

[Anonymous No.1325704]

>>1325703
yep thats what i meant
ill give it a shot i guess

[Anonymous No.1325717]

>>1325686
The typical supply current of a CMOS 555 is less than half a milliampere at Vdd=15V and even less at 5V. The 'placeholder' section of your circuit needs a re-design.

[Anonymous No.1325815]

>>1323439
Why the fuck would anyone build a fully discrete amplifier these days?

There are single stage high power audio amp ICs with THD of sub 0.01%. It might be a bit more expensive but you don't have to fuck around with literally dozens of different transistor characteristics. More components makes things more complicated which means more failure modes, and since you obviously don't have much real world experience you're just shooting yourself in the foot.

[Anonymous No.1325836]

>>1325815
Because they find it interesting. You are not required to understand that.

[Anonymous No.1325848]

>>1325815
sometimes, it's the journey, not the destination. you are not required to understand that (but it sure would help)

[Anonymous No.1325849]

>>1325836
It's more like some faggot took circuits101 and wants to show how "smart" they are to a bunch of people who know better.

[Anonymous No.1325857]

>>1325849
>t.too tryhard to be seen to fail

[Anonymous No.1325904]

psycho sunday

[Anonymous No.1325967]

Do I *really* have to learn to look at schematics with electron flow notation in mind?

[Anonymous No.1325969]

>>1325967
no. just follow the engineering (wrong) notation consistently like everyone else and it'll become second nature pretty fast.

[Anonymous No.1325971]

>>1325969
Thank god. I could probably learn to look at diodes in reverse but it seems like a big pain.

[Anonymous No.1325974]

I started writing this post asking for help before I realized I was using a negative number as the magnitude for the capacitor's impedance and it was throwing off my calculations because I'm actually retarded.
Is the current through the capacitor 29.22 amps with a phase shift of -110.195 degrees?

[Anonymous No.1325981]

>>1325629
No. And that diagram is taken from the SA602 datasheet. I'd imagine the IC was extensively characterized and the datasheet is accurate. More than likely you are misunderstanding something.

[Anonymous No.1325983]

>>1325974
I don't think so. By adding the complex impedances together, calculating the total current flowing, calculating the voltage dropped across the 2Ω, and dividing that voltage by the impedance of the capacitor, I got 47A peak (33.33A rms) with a phase shift of 63°, which is a pretty nice round number and probably the correct answer. What method were you using?

I also threw it into spice, but it gave me a 50A sine with no phase shift at all, so I'll ignore it.

[Anonymous No.1325988]

>>1325967
It is possible to see it both ways at once, you know.
Be conscious that positive voltage is actually a pulling force that pulls electrons up from lower voltage. The voltage is positive, the current that results from it is also positive, but the electrons are pulled not pushed.

[Anonymous No.1325991]

>>1325983
>What method were you using?
I'm trying to find the complex impedances of everything and then add them up, but I think I'm fucking up the parallel branch. I tried again, and ended up with (2.25, -1.25j) for the whole circuit. Does that sound right or did I make an error?

[Anonymous No.1325993]

>>1325991
X1 = 2+2j
X2 = -1j
X1+2 = 0.4-1.2j
Xt = 2.4-1.2j

[Anonymous No.1326160]

>>1325981
>No.
You are not alone..
The (correct) 1991 diagram is from the Philips application note AN1982.
The Power of Copy & Paste can supersede even the most obvious error.

[Anonymous No.1326228]

Does anybody know where I can buy a low value SMD resistor kit? I need 0.1 ohms all the way up to 1 ohm. Aliexpress only has separate reel strips, I don't need that many, I need around 10-20 of each value.

[Anonymous No.1326250]

>>1325983
>>1325993
I came back to it this morning, you're right.
My problem came from doing the inverses of complex numbers in a stupid convoluted way.
Thanks for the help!

[Anonymous No.1326271]

>>1326160
kek, mapmaker's error

>>1326228
here you go, reels of 5 :^) https://www.aliexpress.com/item/50PCS-1-2512-SMD-Resistor-Samples-kit-10-valueX5pcs-50pcs-1R00-R500-R470-R330-R220-R200/32826742429.html

[Anonymous No.1326389]

I want to create a lamp using an arduino uno r3 and RGB LEDs. How do I figure out how many LEDs I can power from it? Is 16 too many to power? I wouldn't know where to start for the calculation. I'd like to use the PWM outputs rather than the analog.

[Anonymous No.1326394]

>>1326389
If you're planning on powering them from Arduino's pins then 1 is too many, especially RGB.
You need a proper power source than can output a few amps of current. Arduino can do fraction of that.

[Anonymous No.1326418]

>>1326394
>1 is too many
6 PWM ports, 40mA each = 2 RGB LEDs, because 2x3=6.
'that funny smell, all these scorch marks..'
From 10 Ways to Destroy an Arduino

[Anonymous No.1326471]

>>1324480
>>1324540
>>1324543
>>1324732
Ok, i'm still getting LAMP ERROR CODE when i turn the tv on, although now i believe the signaling led is as bright as it should be. Not really sure what to do here, i started tracing the power, researching what some parts were and whatnot. I guess it's time to learn psu circuits.
Does anybody know a good source to learn some information on how to decipher what's wrong with this circuit?

There's no power to the mosfet i replaced, or any of the other three, i checked the ic that runs them, and i traced it to a lead that goes to the motherboard i believe, so would i needd to disattach the mobo from the tv and connect to the psu to actually test it properly?

[Anonymous No.1326510]

How can i plug 200 smd temperature sensors to a single microcontroller while avoiding crosstalk, EMC and other bullshit?

[Anonymous No.1326517]

>>1326471
I'd start with the service manual for that model. have you looked for that yet?

[Anonymous No.1326528]

>>1326510
One at a time.

[Anonymous No.1326570]

>>1326510
stop posting this shit without more details about your application.

[Anonymous No.1326578]

>>1325646
Install incandescent light bulbs in series to each branch. Incandescent light bulbs are natural current stabilizers.

For example 12V 36W light bulb would pull roughly 3A when it's supplied with 6-12V.

If you have six COB in series and voltage drop on each COB is 26...29V then the total difference is 18V, thus you can install a 24V incandescent light bulb with enough wattage to provide the needed amount of current (or few 24V light bulb in parallel).

[Anonymous No.1326581]

>>1326271
Thanks m8y, I was able to find a cheaper 1206 pack thanks to you.
>>1326389
Arduino has 40mA or so outputs, you need to use a transistor, like an irf540 MOSFET. Here's a wizard that will help you with the LED configuration http://led.linear1.org/led.wiz once you have that, connect one end to the power supply and the other end to the MOSFET's drain.

[Anonymous No.1326594]

>>1326510
Use ADC’s on each sensor and send the data back digitally.

[Anonymous No.1326643]

I usually do arduino programming but I have a bunch of atmega8s laying around and need to use vusb. I dont fully understand hid programming. Ive been looking at examples of just using an atmega8 as a type of controller consisting of only buttons. But the closest thing I can find is https://github.com/raphnet/usb_game12/blob/master/main.c which is only 12 buttons and Im looking for 14 or more. I dont really understand how I would add more.
Alternatively theres this for the atmega88
http://www.avrfreaks.net/forum/atmega328p-v-usb-button-box
The thread is talking about adapting it from an atmega88 to atmega328 but Im curious if I can adapt it to an atmega8.
Any guidance would be appreciated.

[Anonymous No.1326649]

>>1326643
see the snes_descriptor.c file, where the buttons offered by the device are described (USAGE_MAXIMUM and REPORT_COUNT)
also increase the REPORT_SIZE #define in analog.c and/or twelve.c
for best results, add buttons in groups of 8 to prevent having to wade through the HID spec to figure out which end of the last byte to pad
if you need to add more inputs, you could chain 74HC165s to read many many moar buttons, using the SPI port (recommended if available) or bit-banging the clock and data lines, all limited only by V-USB's packet size or available RAM. the parallel load pins on the '165s are of the wrong polarity to directly hook to the SPI module's automatic SS' so you would need an inverter on the SS' output or to use a separate GPIO to strobe

[Anonymous No.1326653]

>>1326649
>snes_descriptor
Was ignoring that since I thought it was a specific emulator thing. Since I dont need the analog input stuff, I was considering removing those 2 bytes and replacing them with 1 byte for another 8 buttons. Or maybe two because I dont want to screw up the expected array anywhere.
I appreciate the help. My goal is to reverse engineer this to the point of being able to make something on my own.

[Anonymous No.1326661]

>>1326653
heh, so was I, but I didn't see the report descriptor anywhere else, soooooo I had a look
I still suggest you set aside a few hours and read the HID class spec, so that you understand the report descriptor and how the host uses it to turn the report into actionable key/button presses etc. some HID hosts might not be too helpful in reporting errors and inconsistencies to the developer

[Anonymous No.1326698]

I want to make a flexible pcb with an array of 200 sensors to measure temperature of women breasts, however im not sure if i should use I2C for this, SPI or what since i have never used above 10 sensors for this

What kind of uC should i go for?

Also should i stick to Digital or analog sensors any advantages?

I'm thinking on using TI TMP104 http://www.ti.com/lit/ds/symlink/tmp104.pdf

[Anonymous No.1326700]

>>1326698
I2C has a 7-bit wide address field so you can't get more than 128 devices in a single network. With SPI slave select is a separate wire so a network of 200 is a lot of wires. Use a UC with two I2C buses.

[Anonymous No.1326704]

>>1326698
those are decent sensors. nice and smol
>uC
looks like you would want something with plenty of UARTs, for fastest scanning. if you don't have one UART for each row, you could use an outboard demux and data selector for each RXD and TXD, to connect the uC to your chosen rows in turn to be worked
do you just want to push all the data back to a PC, or do more with it onboard? STM32F1xx USB variants should be plenty for pushing data back via USB. maybe something more upscale would be needed if you wanted to display a heat map on an LCD or something like that

[Anonymous No.1326712]

>>1326389
Use a transistor and a separate power source for the LEDs.

[Anonymous No.1326749]

>>1326700
so... how do you deal with 200 tracks in a pcb/flex circuit without having crosstalk/EMC all over the place, ?

[Anonymous No.1326755]

Was browsing for embedded jobs

suddenly read "Experience with DFM or DFT"

what the fuck does this mean?

Design for Manufacture and Decision field theory??

WHY ARE THESE 2 IN THE SAME LINE

send help pls

[Anonymous No.1326780]

Is there anyway to bring old NI-CD and NI-MH cells back from the brink?

I've got some that take a charge but will slowly self discharge themselves to less than 1.2v over a few days and will eventually read 0v.

They don't need to be 100% like new but would like to salvage what I can.

[Anonymous No.1326783]

>>1326749
Crosstalk has to be super bad to corrupt a digital signal in the first place and that's not even what SPI slave select is. Only one SPI slave select wire can ever be high at a time and it's not used to transmit data. It's just a signal to tell one slave at a time it should start reading and writing to the bus.

[Anonymous No.1326788]

>>1326755
DFT is design for testing. It's not the same thing as design for manufacturing.

I once had a firmware dev job where I had to desolder a bunch of shit to get the JTAG to work, then solder it all back on to test the code I'd flashed. I don't think the guy who designed it knew what DFT stood for either.

[Anonymous No.1326789]

Any one have any experience with designing pcbs for tube circuits? Any pro tips? I was going to run the heaters dc to minimize routing issues, I reckon. Any input is appreciated.

[Anonymous No.1326875]

>>1326788
so basically

Design for Manufacture (setup gerbers, remove programming pins, prepare silkscreens)

Design for testing (Add Testing nodes for oscilloscopes/voltmeters, removable microcontroller, led indicators)

[Anonymous No.1326876]

>>1326581
thank you very much

[Anonymous No.1326896]

>>1326780
sometimes. there are reports of people discharging large caps into them to clear out dendrites. there aren't many reports of people blowing their hands off in the process, so they must be taking good or even paranoid safety precautions, OR they just haven't typed out their reports yet

>>1326875
DFM is a paradigm, not a task. the general idea is to match the design to manufacturing capabilities e.g. designing a board to be wave-soldered vs reflow-soldered, reducing processing steps to reduce cost such as SMT vs. THT or fewer pcb layers
aside from making sure the JTAG ports are available, DFM and DFT together suggest work at the semiconductor level: designing a chip that works well over process/voltage/temperature variations, and designing it to be fully testable from the outside

>>1326789
speaking of DFM, kek
yes, run those heaters dc. pc mount tube sockets can be nice but could end up prohibitively large for multiple-tube designs. obvs keep grid lines short. most tube circuits aren't high current so usual cautions related to solid-state design don't necessarily apply, but keep voltage carrying lines wide apart (see also creepage distance)
it's a good idea to add a neon lamp and resistor across the B supply to discourage your mitts from poking around the circuit when powered
aside from that, whatcha makin?

[Anonymous No.1326904]

>>1326896
hmm, so it may be best to just discard them? I have a 5000uF 330v capacitor bank at my disposable.

[Anonymous No.1326926]

>>1326789
transformers are the most expensive part so build around the transformers that you can easily get. primary and secondary output voltage and current ratings will limit your tube selection. use balancing resistors across your heaters. decouple all your grounds on the signal side to reduce hum

[Anonymous No.1326941]

>>1326904
If a NiCd has 0V and shows a short you can try the capacitor thing. I did this a few times and the process is totally harmless. I used a 4.7mF/40V capacitor charged to 30V and discharged it through the NiCd cell by hand, without any precautions. You get a crack and a small spark in the moment of contact and after that the internal short from the metal whiskers was gone, you could charge it again. It's not worth it, the capacity of the 'rescued' NiCd is as small as it was before. You do it only if you have no replacement.

[Anonymous No.1326980]

>>1326896
I would like to build a couple of preamps for guitar and bass. A Soldano SLO type preamp that I intend on tapping into my twin reverb (which I built, it was in the pic of my first post) just before the reverb stage. As well I’d like to build an alembic style preamp for bass to DI into my interface. Everything I want to build is relatively small and I am takin a modular approach.

Thank you for you input. Good ideas.

[Anonymous No.1326991]

>>1326980

>>1326896
Also: (sorry I just woke up and forgot to ask the relevant questions) Do I need to take care with trace width on, say, the B+ or heater lines? If I am using a transformer with 6.3V secondaries will this be sufficient after rectification and filtering? If not is there any way to make it work? Say a doubler then regulator, maybe. I’ve seen that guys have done it but I would really rather not have a weak design if I can help it. Also is it worthwhile and advantageous to place different signal types on different layers? Sorry for the perhaps dumb questions but I’m a lowly technician and all of the circuits I’ve designed or modified for this type of thing have been eyelet boards. Trying to step it up into the late 20th century via EAGLE here.

[Anonymous No.1327012]

I want to compactify a series RLC circuit with fairly high L and C values by wrapping a fuckload of super fine wire around an electrolytic capacitor and letting the R be made up by the resistance of the wire itself. But would having the capacitor INSIDE of the coil fuck with it in some way? We're talking on the order of hundreds of ohms, a few millihenries (several thousand turns) of enameled magnet wire wrapped around an axial couple-hundred uF ~50V aluminum electrolytic.
I'm aware that there's a magnetic field generated inside of a coil with current passing through it, and that capacitors function on the premise of producing electric fields across a dielectric, but I'm too dumb to figure out what the interplay, if any, would be.

[Anonymous No.1327014]

Let's say I have a 3 prong 240v outlet (l1, l2, g, no neutral). If I were to take a 4 prong 240v outlet and try to use the neutral of a 120v socket (just use a screw together plug and only hook up the neutral) would this work or would I end up tripping/frying something?

[Anonymous No.1327033]

>>1327014
See for yourself.

[Anonymous No.1327034]

So I have this old guitar effects pedal. Its a breddy gewd pedal but the adapter is toast.

The UL listing says its an 8 watt input (110v 60z at the wall, burger here)

It says its a 40v DC output, 1,000 mA

My only question, is making something like this a reasonable first project in electronics? Or should I save my time and start with something easier.

[Anonymous No.1327038]

>>1327014

What the fuck are you trying to do? If you are trying to put a 4 prong where a 3 prong used to be, just use ground (green wire) as neutral. Hook nothing up to the ground terminal on the receptacle. My company does it all the time. Its fine by code most places. Better than voiding your UL for sure

[Anonymous No.1327042]

Fake post time?

[Anonymous No.1327045]

>>1326991
B+ traces don't need to be wide, but observe precautions to prevent arcing or other electrical strain http://www.smps.us/pcbtracespacing.html
heaters will generally pull a fair amount of current. try to keep those traces kinda wide
6.3V secondaries should be fine. for 12AX7 dual triodes you would of course connect the ends to one side of the heater supply and the center tap to the other
>layers
probably not really. a double-sided layout should be fine, just use as much of the topside as a ground plane and route your signals and powers underneath. of course, consider shielded sockets. four layers would probably be overkill. if you're using tubes you're probably not all that worried about density anyway

>>1327012
electrolytic caps are often themselves coils of foil. you sure you don't want to connect a few 10uF multilayer ceramic caps together instead?

>>1327034
>40Vdc 1000mA
sounds like one too many zeroes
a transformer-driven dc power supply project is hard to fuck up as long as you don't connect anything backwards. finding the right transformer might be the hard part

>>1327042
it's that time of day again

[Anonymous No.1327051]

>>1327033
Soooo it would be fine or...?

>>1327038
no.

[Anonymous No.1327055]

>>1327051

>no

Lmao, then I hope you have a perfectly balanced load, otherwise, enjoy your energized appliance fag

[Anonymous No.1327065]

>>1325307
>>1325336
>temp control in the background
It's obviously a 'stick' version of pic related.
The 'gun' is a transformer reducing the mains input to a volt or so at high current.
Your transformer is in the box with the switch to select different taps for higher or lower power.
I've actually made a tip for one by deforming copper house wire to suit.
>beat the wire kinda flat in the middle
>fold the wire in the center of the flat part
>bend the ends to fit the lock-nuts
>all done

[Anonymous No.1327074]

>>1326991
What drives the (costly because obsolete) optocouplers VR1..4?

[Anonymous No.1327132]

>>1327055
>hurr lemme just say fuck the ground and hook it to the neutral
>durr if you ground your neutral youre gonna have a hot case
instead of a captcha you should have to take an iq test to post
>lol fagggggggggggg
pot, meet kettle

[Anonymous No.1327156]

>>1327074
Those will not actually be in what I am making as they are there to switch channels and I’m only building the OD channel. But they are switched with a foot switch on the SLO 100.

>>1327045
Thank you again. Very informative.

[Anonymous No.1327333]

>>1327065
Thanks for the info.
>>1325369
I tried it and it actually works. Never would've guessed.

[Anonymous No.1327343]

>>1327132

Lol. try it yourself and see what happens chump. I hope i realize "a 120v wall outlet" as you put it, uses #14 awg. Whatever your 240 shit, its probably #8s. Your neutral will be massively undersized. Something will probably go wrong. Whether you have a load on your ground/chassis, or the neutral your stealing is part of a network and its gonna instant trip every time.

>has safety concerns about not hooking up green ground wire to ground terminal on plug
>wants to nigger rig terminals off a 110/15a receptacle and wire from a 15a circuit onto a 220v receptacle

Its your house, you can burn it down if you want.

[Anonymous No.1327368]

>>1326991
> 6.3V secondaries will this be sufficient after rectification and filtering?
Depending on the filter capacitor size, the end result can be anything between serious undervoltage and overvoltage. If you want maximal hum reduction, you'll end up overvolting the heaters. If you want to filter the heater voltage, consider doing that for the input stages only and adding a series resistor to reduce voltage.
>trace width on, say, the B+ or heater lines?
The heaters take several amperes, so use somewhat thicker traces for them. There are trace width calculators available for determining suitable width. B+ is pretty low current, but you need to pay attention to clearances.
>is it worthwhile and advantageous to place different signal types on different layers
It is more important to pay attention to the layout in general so that the routing remains short, the grounds are good and that you aren't routing sensitive signals near the noisy ones. More layers makes it easier. That said, when the tubes were still relevant, the PCBs were predominantly single layer. If you need more than 2 layers, you're doing something wrong.

>>1327012
The can is made of aluminum, which will kill your coil's inductance.

[Anonymous No.1327432]

>>1327343
because when you use a 240v welder or oven or whatever the 120v totally isn't used solely for the display and controls with the 240v doing the actual legwork

[Anonymous No.1327627]

Does anybody here have experience with windshield washer pumps? I'm considering using one for a project where I want to squirt small amounts of water up to a few meters away, once every few minutes. Would these pumps do the job? What kind of power/current do they draw, does anybody know?

[Anonymous No.1327650]

>>1326517
Yea, found it, this page here shows the error code, 1st 1 in brackets.
Is ERR_PNL (19 pin) referring to the main ic?

[Anonymous No.1327658]

>>1327650
page 7-1 says the monitor microprocessor is IC2001
did you try clearing the counts in process A, whatever that is?
also is it possible the lamps and/or the on-board fuse are, in fact, blown?
I believe you'd need a scope to get much further into this unless you buy a repair parts kit such as Pic related

[Anonymous No.1327688]

>>1327627
A long time ago my parents had a station wagon with a rear windshield wiper and washer where the nozzle was broken so the stream was directed directly backwards instead of towards the window. It shot pretty far.
They are all going to be 12-15v rated if it's pulled off of a car. I cant imagine it would pull more than an amp, so you can probably just wire it directly to a 12v wall wart with a switch and be done with it. I don't know if they use the type of motors where you could get faster pumping / more pressure simply by upping the voltage, but its worth a shot.

[Anonymous No.1327693]

>>1327650
actually, hold off on the repair parts kit, it may or may not be relevant to this side of the circuit. but do take a pic of the repair, for quality control purposes
after you check the LED bank and clear the lamp failure counter in process A, whatever the fuck that is, also check the stuff downstream of the blown FET. on various pics around the net I see some small SMD bits on the return line from the LED banks that might serve as lamp fail sensors and might have blown along with that FET
did you also do the big diode by the transformer (D7215D I think)?

[Anonymous No.1327695]

>>1327688
Thanks. I was asking about power because it's for a battery-powered robot

[Anonymous No.1327697]

>>1327688
>Typical wattage for a 12V washer pump is around 45/50W with a maximum current of 5 Amps. A 7.5 Amp fuse should be OK for your purpose.
imagine harder

[Anonymous No.1327698]

>>1327695
yeah, those are hungry little sons of bitches. if you can't feed it 5A, consider the micropumps from our esteemd chink friends

[Anonymous No.1327710]

>>1327698
>5A
Yeah I think that's actually doable, unless I've completely misunderstood how to calculate this stuff. But right now I'm looking at this kind of batteries: https://hobbyking.com/en_us/turnigy-2200mah-3s-25c-lipo-pack.html?___store=en_us (might go higher on the capacity, but it depends on how much space I want to take up on my rover). The way I understand you calculate the discharge rate with the C rating is you multiply it by the capacity (somehow converted to ampere), which would give plenty of room seeing how most of these LiPo batteries I've seen don't go under 20C and I'm looking for something with 3000mAh and above, which would give a maximum discharge current of 60A

>micropumps from our esteemd chink friends
You mean like aquarium pumps from aliexpress? Or something else?

[Anonymous No.1327725]

>>1327710
"nC" is the discharge rate, where n = the number of like packs you could discharge in 1 hour
that pack would do, though the voltage might be a little lower than an automotive component would expect. also, auxiliary automotive components like windshield pumps aren't really designed for maximum power efficiency, more toward maximum cost efficiency. just sayin
>micropumps
pretty much. some of them in the $5-$10 range are designed to run on the low side of 12Vdc and also have enough lift to drive a respectable nozzle for long distance shootin'

[Anonymous No.1327732]

>>1327725
I went with 11.1V because i'm also using a couple of 12V motors and the alternative was 14.8V, so between the two I thought i'd go with the 11.1V.
> cost efficiency
Hadn't thought of that, cheers

I'll also have a look at the chinese stuff. Thanks for the pointers

[Anonymous No.1327739]

I just bought my first genuine hakko fx888d station and the manual states "temp setting" and "adjustment setting" what is the difference? i thought the iron regulates the set temp and thats it. do they mean calibrate when they say "adjustment" ?

please explain. thanks

[Anonymous No.1327742]

>>1327739
mostly for industrial users going for strict reproducibility
>*Adjust the tip temperature to match the set temperature in case that there is a difference between those temperatures due to tip shape, heater replacement, or other factors.

[Anonymous No.1327746]

>>1327627
>small amounts of water up to a few meters away, once every few minutes
Doesn't that sound like a job for a piston pump?

[Anonymous No.1327748]

>>1327742
so in basic words its calibration when changing tip size, heat element etc. why don't they call it calibrate instead of "adjustment" like that is confusing to new people because i see "temp setting" and then "adjustment setting" sounds VERY similar in English. probably asian language barrier when writing the manual.

and if that line you quoted is in the manual im going to be embarrassed. i should have read it better.

[Anonymous No.1327754]

>>1327748
adjustment is the right word for it, reflecting its intended purpose as a temporary offset for particular tooling. calibration is something you send equipment out for
I grabbed that line off of hakko.com, no idea whether it's in the manual

[Anonymous No.1327756]

>>1327754
it says very similar but not exactly that otherwise i would have understood it straight away.

so i can just use the presets which are 250c to 450c in 50c increments. if i change to larger tip ill up it to 50c extra to make up for larger surface area needed to keep the heat and not worry about offsetting/adjustment mode. this isnt for industrial.

[Anonymous No.1327765]

>>1327739
>fx888d
D = digital deception
https://www.hakkousa.com/products/accessories/tip-thermometers/fg100-02.html
Availability: In stock
List Price: $230.07

[Anonymous No.1327775]

>>1327765
They used a thermocouple directly at the tip for a reason. The display doesn't show that.

[Anonymous No.1327794]

>>1327756
I'd suggest resetting them to 300°C-400°C in 25°C increments. for lead-free you're highly unlikely to use anything lower than 325°C

>>1327775
>1.6mm diameter
wew

[Anonymous No.1327893]

>>1327794
ill be using leaded. what setting should i use. it seems when using 350c on station the tip goes up 100c extra when soldering is added in a hakko.com video. wtf

[Anonymous No.1327928]

>>1327893
>using anything over 300

[Anonymous No.1328001]

I finally used the hakko today and i got rid of the lead-free solder on my tips and put nice leaded solder on them. i should have bought one sooner, no more turning on/off every 3 minutes. what a blessing. and the tips dont even oxide as fast. no worry about overheating. god damn what the fuck. i was missing out on glorious soldering!!!!! screw unregulated irons from now on.

[Anonymous No.1328056]

>>1328001
Congrats. Lead-free is crap and only required for mass production. If you believe in numbers, a trusted reference is Sn63/Pb37. It melts at 183 °C (361 °F) (eutectic alloy, solidus = liquidus temperature), 60/40 becomes liquid between 183–190 °C (361–374 °F).

I mostly use 0.7mm Sn60Pb38Cu2, sometimes 1mm Sn60Pb39Cu1 (both 3.5% non-corrosive, no-clean flux core) and my favourite tip is the small (~2mm) chisel type. Pen-type iron is 24V 25W, power adjustable <10..100% with a knob on my self-made power supply. The temperature I still regulate by hand: South = idle and tip change, West = solder wire melts, North-West = optimal for solder bridges on dot board, North = normal soldering, North-East = soldering with long and pointy tips, East = max power, rarely used. I guess my normal soldering temperature is about 250°C.

[Anonymous No.1328072]

>>1328056
>Lead-free is crap
git gud

[Anonymous No.1328093]

I'm building a cisco lab. The tiny little fans the switches and routers come with are fucking terrible.
So I want to dremel out holes in the cases and mount case fans above the ICs.
I just don't know how I'd power the fans.
It'd probably be best in parallel, but how would I actually wire them up? And how would I supply power?

[Anonymous No.1328096]

>>1328093
The fans are going to be larger so they're probably going to draw more current than the smaller fans
is there any danger in hooking the larger fans up to the router's own fan pins?

[Anonymous No.1328204]

>>1328096
Larger doesn't always mean more current. I have a super silent 60x60x25 mm 12V fan that only needs 20mA (240mW). The 50x50x10 mm fan I replaced had 90mA and 1.1W.

[Anonymous No.1328245]

I'm a retard that doesn't understand the use of a capacitor

[Anonymous No.1328253]

>>1328245
congratulations

[Anonymous No.1328262]

>>1328245
>the use of a capacitor
Adjust the power factor of the grid?

[Anonymous No.1328399]

>>1327928
This

[Anonymous No.1328401]

>>1328245
most capacitors, by volume, are just used to smooth out DC power. wire/pcb trace resistances and inductance mean that when circuitry suddenly decides to consume a big chunk of power the voltage supplied to the device can drop and cause issues. capacitors store energy. you can use them as a tiny battery to supply that energy right next to the device, bypassing all the resistances.

[Anonymous No.1328403]

>>1328072
https://nepp.nasa.gov/whisker/
Glorious lead filled, cancer paste, master race!

[Anonymous No.1328404]

>>1328262
This guy first year engineers

[Anonymous No.1328431]

>>1328403
>muh whiskers
>muh hi-rel lolduino project
I see it does cause cancer

[Anonymous No.1328445]

>>1328431
if you haven't replaced the controller in your grandma's dialysis machine with a chinese arduino you're no hobbyist

[Anonymous No.1328482]

The RoHS directive came into effect in July of 2006. Because of the problems with higher temperatures and tin whiskers there are exceptions for medical, military and measuring devices. Private use of leaded solder wire is not regulated, only industrial production. Since leaded and lead free solder should no be mixed you need two sets of tips and solder wire for repair work.

[Anonymous No.1328580]

>>1322757
Hey /ohm/ I'm doing joule heating for a project. Was using batteries, but I need more heat than 9v and they get used up too fast.

What would be a better way to generate constant 12-24v? I can't just use a generic 12v power supply and attach both ends to the copper I am heating because that will just short circuit right?

[Anonymous No.1328584]

can anyone tell me about a uC with 2 I2C ports?

[Anonymous No.1328595]

>>1328401
Thanks fren

[Anonymous No.1328602]

>>1322865
I like how it autistically shakes

[Anonymous No.1328609]

>>1328580
You probably should be using lithium batteries, since they are one of the densest ways to store energy. Why do you need 12V? Can't you reduce the resiatance of the heating element in order to have the same amount of power?
You can use a power supply as long as you don't exceed it's power rating, for example, if you have a 50W PSU and you're outputting 12 volts you need to use a resistance which value is 2.88 ohms or higher. Ohms law and power formula mix, power equals voltage squared divided by resistance.

[Anonymous No.1328640]

>>1328609
https://www.youtube.com/watch?v=JLUrNS8mZVA
https://dspace.mit.edu/openaccess-disseminate/1721.1/97478
Basically I heat some copper wire wound around nylon to create linear actuators. I calculated that 9v(8.5) would give me the temp I needed (120-150F) with the resistance of my Copper. But it takes a while to heat up and I want faster contractions/motions of the actuator. Saw some labs using 12-15v and getting much faster contractions.

So I have to put a certain amount of resistance(2.88ohm) on the wire in order to not fry/short-circuit my PSU?
I do have some spare PSUs laying around I could use. Do you think using the 12v and -12v pins might damage the PSU if I use it for joule heating?

[Anonymous No.1328673]

>>1328640
In most ATX PSUs, the -12 V line has a lower max current output than the +12 V one.

[Anonymous No.1328690]

>>1328640
>the resistance of my Copper
What is the diameter and the length of your conductor? Please post your calculation regarding the temperature.

[Anonymous No.1328693]

>>1328584
yes, they exist
look for devices that have a multi-functional serial interface block. some of them have SPI and I2C modes. consider STM32F103Cx

>>1328640
>not using nichrome

[Anonymous No.1328717]

>>1328673
So I would have to decrease the voltage a noticeable amount then right? I guess I could just send it to ground...

>>1328690
136F = 9v^2 X 1.68ohms
Formula for joule heat I was using.

>>1328693
You got me there. I just have a lot of speaker wire on hand.

[Anonymous No.1328763]

>>1328717
>speaker wire
Use magnet wire because miracles.

[Anonymous No.1328781]

>>1328717
>mixing metric and burger
>not making a working copy of a working design before throwing your junk box at it and having no clue why it isn't working as well as a professional setup
>not understanding that resistance is practically the conversion of electrical power to thermal power
>not understanding why heating elements almost never use copper
wew lad

[Anonymous No.1328801]

Hey folks, can someone tell me some good Beginner-tier books IN GERMAN?
Been looking around Amazon, but not sure what might be suitable. I'm getting into soldering, already made some really easy circuits (just 2 or 3 leds, some resistors, nothing special).
But now I would like to go more into detail. Also I'm opting to go taking a Electricians apprenticeship, would be nice to have some knowledge beforehand.

Tanks in advance.

[Anonymous No.1328817]

>>1328801
power electronics is a different world from small-signal electronics. the basic physics is universal. the different scales of power, time, and cost, all radically affect the practice. generally, small-signal praxis is according to theory, while power praxis is according to regulation and procedure.
know Ohm's Law and Kirchhoff's Current and Voltage Laws. then you're already ahead.

[Anonymous No.1328819]

!ACHTUNG!
NEUE FADEN
>>1328818
>>1328818
>>1328818
NEW THREAD
!ATTENTION!

[Anonymous No.1328882]

>>1328482
>Since leaded and lead free solder should no be mixed you need two sets of tips and solder wire for repair work.

source?

also would solder wick clean be enough then i can put leaded solder over the top where leaded-free solder was used? even solder wick doesnt remove every bit, it leaves a micro layer of solder behind

[Anonymous No.1329108]

More videos I've looked at:
http://www.connorthomasstevens.com/Manyforms-Heat-Actuated-Nylon-Muscles
https://www.youtube.com/watch?v=LslvphbXNYc

>>1328781
Oh I'm an idiot, I'm getting close to 280F but I never converted it. I have actuation and working projects, picture related. #2 is strong enough to lift a bowling ball about an inch and it uses copper+9v battery.

What would you recommend I use, nickel? I'm gonna try a 12v PSU out and just send to ground.