/ohm/ - electronics general, never have I ever edition

[Anonymous No.1640236]

beyond-the-rails thread: >>1634051

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

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

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

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

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

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

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

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

[Anonymous No.1640237]

this thread's digits brought to you in part by the CP40236 Peltier module

[Anonymous No.1640246]

>>1640237
i want to do something with a peltier but i'm too lazy

[Anonymous No.1640279]

I bought some 575a rectifiers because I was drunk and retarded.

[Anonymous No.1640288]

>local community college is eliminating their electronics program this semester in favor of pretty much every other trade

it's not fair bros...

[Anonymous No.1640291]

>>1640288
see if you can buy their equipment on the cheap.

[Anonymous No.1640299]

>>1640236
That image doesn't make sense. Both the voltage and resistance ranges are high impedance inputs on most meters. Only the current range is a near short. Measuring resistance on an active circuit at 200V shouldn't make a difference. It'll be a garbage reading but it shouldn't melt.

[Anonymous No.1640300]

>>1640246
This
Also they use quite a bit of power
>>1640288
This is a bad move, but also this >>1640291
So uh is this gonna be the thread then?

[Anonymous No.1640308]

>>1640299
the current source that ohmmeters use could have been damaged catastrophically, and the rest of the meter could have followed in a chain reaction given a bit of ionization
>coincidentally reading about thyratrons on wikipedia rn

>>1640300
with so many in this general filtering namefags, I suppose few saw the other thread posted by Pic related. I didn't

[Anonymous No.1640310]

>>1640282
Okay that was my general understanding too. What does the capacitor between the two ADC inputs do? I've seen something similar before, in addition to RC filters (additional caps to ground on each resistor)
Also, was that a similar thing to what was suggested earlier for the instrumentation opamp inputs? 33ohm resistors, caps to ground, and maybe a cap across the inputs? Where would the input protection diodes go? Directly at the inputs? or before the RC filters?

[Anonymous No.1640346]

>>1640236
Image+story look fake and Rule 4 is a meaningless statement.

[Anonymous No.1640395]

>>1640346
I think he thinks he could get beppu banned for posting itt

[Anonymous No.1640480]

I have seen countless videos where pajeets and such grab power lines and melt instantly, so how the fuck is this pupper still alive?

[Anonymous No.1640484]

Can I make this LED strip battery powered?

It's controlled via wifi, on the device it says anything greater than 3m requires 25W.

[Anonymous No.1640487]

>>1640480
Looks like he had no path to ground and/or he missed out on the recloser. Dry night. Those lines should of flashed hard when they went phase to phase too. Little guy is lucky af.

[Anonymous No.1640492]

>>1640487
You can see he got clearly zapped since he went full statue mode when he touched the wire

[Anonymous No.1640496]

>>1640492
Prob missed it, it was fast. In any case it didn't have a full path to ground or he'd be jerky right now.

[Anonymous No.1640498]

>>1640310
it's the C in an RC filter. because Kirchhoff's circuit laws are commutative, f(c) = 1/(2*pi*(R1+R2)*C)
protection diodes... I first wanted to put them after the resistors to keep them from failing during a nasty fault condition, say, the current source fails short. under normal operation the inductor current won't exceed the defined test current. therefore, barring outside excitation, neither diode will ever see more than the test current. unfortunately that is probably more than the analog or digital parts of the circuit care to consume, which would make for blown gates and an all-around bad time. one of the other advantages of using a low sense voltage, where the diodes won't steal any appreciable current under normal operation, is that you can move the gray diode to the yellow-highlighted position and not worry about dumping fault current into the 3.3V rail, at the cost of a few milliwatts dissipated in the + input resistor
yes, that is the filter I suggested earlier, but I drew the RC filter in the wrong stage on the previous schematic because lazy. Pic related is more like it

>>1640346
>>>/news/

>>1640395
not necessarily banned, just wanted them to stop

>>1640484
yeah get an inverter. other solutions are beyond your capabilities

>>1640480
cats are stubborn, therefore their internal resistance is higher

[Anonymous No.1640506]

>>1640498
Inverter? AC/DC?
Amazon is giving me 200usd vs 15usd options.

[Anonymous No.1640511]

>>1640484
>It's controlled via wifi,
not even once

[Anonymous No.1640513]

>>1640506
Get one of those 12vdc to 120vac car inverters. A basic 100-ish watt one will be plenty and dirt cheap.

[Anonymous No.1640519]

>>1640511
Works great for me. Or do you mean once batterysupplied?

>>1640513
Ooh, those look nice. But the one I have requires 24v, what's up with that? Most other led strips do 12v.

[Anonymous No.1640557]

>>1640519
>Works great for me.
so far

[Anonymous No.1640558]

>>1640519
>Ooh, those look nice
What anon means is battery (12v nominal) -> inverter (12v->120v) -> adapter (120v ->24v) -> led strip. And while this isn't efficient, at least you'll be using COTS parts with UL stickers.

[Anonymous No.1640573]

>>1640519
Found: https://www.amazon.co.uk/XTPower%C2%AE-XT-20000QC3-Power-Bank-connection/dp/B07PY8516W/ref=sr_1_4?keywords=24v+battery&qid=1562090028&s=gateway&sr=8-4

Never seen a 24v power bank before. I don't mind if it's chinkshit of actual 8000mAh.
How would this work, a converter is still needed with that?

>>1640557
It's been working great for years.

>>1640558
So:
12/24v battery connected to:
https://www.amazon.co.uk/ASHATA-AC220V-240V-100V-120V-Converter-Transformer-default/dp/B07KTXL1Q4/ref=sr_1_2?keywords=120v+to+24v+converter&qid=1562090518&s=gateway&sr=8-2
Connected to:
https://www.amazon.co.uk/dp/B07CW32SQ8/ref=emc_b_5_i
then to the strip?

[Anonymous No.1640596]

>the virgin heatshrink tubing
>the chad hellermann sleeving
shig dig

[Anonymous No.1640630]

[Anonymous No.1640639]

>>1640299
shit chink multimeters that don't have proper protection circuitry

[Anonymous No.1640657]

it looks like this pad mounted transformer outside my house is gonna make some interesting fireworks soon

[Anonymous No.1640663]

>>1640573
>then to the strip?
Should work, yes

[Anonymous No.1640680]

You guys! Check out this sweet gift I got in the mail today!

[Anonymous No.1640682]

You guys! Check out this sweet gift I got in the mail today!

[Anonymous No.1640686]

>>1640682
>no poison

[Anonymous No.1640688]

>>1640663
Can I run more than 1 strip off the same setup? Simple split out off the 240v/24v converter?

[Anonymous No.1640693]

>>1640498
>the inductor current won't exceed the defined test current
Protecting it from voltage spikes from ringing when disconnecting the inductor.
Which would require diodes on each input no?
>move the gray diode to the yellow-highlighted position and not worry about dumping fault current into the 3.3V rail, at the cost of a few milliwatts dissipated in the + input resistor
I'm more worried about erroneous readings than slight power dissipation from the resistors

[Anonymous No.1640695]

>>1640686
Does straight petroleum jelly count as poison?

It's either that or rebranded sex lube.

[Anonymous No.1640707]

>>1640573
>So:
> 12/24v battery connected to:
> https://www.amazon.co.uk/ASHATA-AC220V-240V-100V-120V-Converter-Transformer-default/dp/B07KTXL1Q4/ref=sr_1_2?keywords=120v+to+24v+converter&qid=1562090518&s=gateway&sr=8-2
> Connected to:
> https://www.amazon.co.uk/dp/B07CW32SQ8/ref=emc_b_5_i
> then to the strip?

What is in this pic:
>>1640484

That can connect to the 120v inverter. no need for another one.

[Anonymous No.1640753]

>>1640688
Do the math.

The adapter can supply 1 amp (though I wouldn't run it full time at that rating). The inverter can supply (150watt / 240v=) 0.625 amps. I don't know how much your LED strip requires.

[Anonymous No.1640786]

>>1640480
>we have acquired electricity
holy kek

[Anonymous No.1640788]

>>1640484
Buy a 24V LED-strip dimmer module without a built-in mains power supply and run it off a 24V battery.

[Anonymous No.1640809]

>>1640682
oh boy no orrosion

[Anonymous No.1640817]

>>1640480
Russia stronk. Cat very angry
.

[Anonymous No.1640834]

>>1640693
>Which would require diodes on each input no?
maybe?
I just put this into a sim and I'm having a bit of trouble getting the clamps to keep the voltage from going too far outside the rails. I added a freewheel diode directly to the sense input and simulated two approaches to deal with its voltage drop during the field collapse: add some legroom to the DUT - lead with a 100mA capable shunt regulator such as the TL431 (simulated here by a 2.4V zener), fed with a resistor to keep it alive at 5mA while force leads are disconnected; or use voltage dividers to attenuate the spikes and compensate with inst amp gain. just for fun I added bias/offset current to one input. the legroom approach perturbed the reading almost not at all and seems to be less dependent on component values. feel free to add the usual clamping diodes back in if you don't think the inst amp's clamps are going to be enough to handle other sudden voltages

>>1640695
petrolatum has no known LD50(oral) but you might wish you were for several hours. if you want to try it, I'll call tomorrow to check on you
>ordering chink flux by way of the Philippines
big mistake Sri

>>1640817
kot may be mad but at least kot is not bliniy

[Anonymous No.1640840]

>>1640237
I came to this board to ask about these things. How viable are they to use in a cooling vest? I'm new here (I'm a fa/tg/uy) so I hope this isn't an annoying question.

[Anonymous No.1640848]

Just read a chapter on diodes and now this graph in a datasheet confuses me. Why is it logarithmic not exponential in shape as expected from the i-v formula? Where is the 'knee voltage'? Or is it a different characteristic?

[Anonymous No.1640851]

>>1640848
oh wait it says something about a pulse? what pulse. is it tested via feeding pulse into it for PWM applications?

[Anonymous No.1640856]

>>1640834
>>ordering chink flux by way of the Philippines
>big mistake Sri

I'm considering it an experiment. It was cheap enough to be low-quality rosin as advertised, but it's this shit instead. I'm attempting an ebay refund without mailing it back to see if that works. Then I'll try to desolder a scrap board to see if it does anything at all.

$2.30 ain't exactly breaking the bank.

[Anonymous No.1640872]

>>1640848
The X axis is linear, the Y axis is logarithmic. So an exponential curve would be a straight line. And between around 0.6 and 1.0 V it is roughly a straight line.

[Anonymous No.1640885]

>>1640872
Ah I didn't notice the Y axis was logarithmic
>So an exponential curve would be a straight line
That makes sense.

>And between around 0.6 and 1.0 V it is roughly a straight line.
OK, but the graph looks logarithmic all the way from 0.6 to 1.8V So the entire graph would be a straight line on a linear scale? Should there be a knee somewhere around 0.7V after which it should shoot straight up pretty sharply?

[Anonymous No.1640891]

>>1640480
He could still have eight lives left...

[Anonymous No.1640942]

>>1640885
>Should there be a knee somewhere around 0.7V

the graph starts at approx 0.62V so the knee has already been passed. this graph is meant to give you a diff kind of perspective than the usual ''hockey stick'' graph. so appreciate it for what it tells you, even if it's not the cliched view you've seen 1000 times before.

[Anonymous No.1640951]

Hey everyone, what's your favourite 7400 IC?

[Anonymous No.1640961]

>>1640834
>i just put this into a sim
I keep forgetting to try it on falstad
Also I don't know how to model bias currents and voltages so I haven't tried that yet
Can you rephrase more simply what modelling the TL431 with a zener and diode is for? That part's got me a bit confused
>voltage drop during field collapse
You mean voltage increase? (unless you mean swinging highly negative in which case absolute increase) Because I have also thought of simply always adding a freewheeling diode when testing an inductor but for the sake of protection, I want to see what I can do so that I can get away with either not doing that, or if i "forget"
Either way its not like it'll be able to test inductors using high currents, so I wouldn't have to worry about the voltage swinging too severely

[Anonymous No.1640962]

>>1640951

[Anonymous No.1640964]

I have an arduino powered by a chinky 220v to 5v dc power source and sometimes when i turn on or off my desk fan the arduino restarts or the capacitive sensor on it triggers.
Is there any way to get rid of this effect?

[Anonymous No.1640967]

>>1640961
the TL431 is an precision shunt regulator that can sink up to 100mA, adjustable from 2.5V to 36V. you could think of it as an adjustable zener, some distant cousin of the LM317
>unless you mean swinging highly negative in which case absolute increase
the sense + terminal swings in the - direction. you may as well just make the freewheel diode a permanent part of the instrument. reverse leakage of the diode is equal to a tiny fraction of an LSB. try that circuit with a 1N4148 and see
>swinging too severely
the inductor resists change in current. at the instant the force + terminal is disconnected, the inductor will be pushing a current equal to and in the same direction as the test current. the load path through which that current is forced determines the voltage. without the freewheel diode, that path probably involves the inst amp substrate and random diodes throughout the device, if not the 3.3V rail and other devices on it

[Anonymous No.1640968]

>>1640967
>>>1640961
>the TL431 is an precision shunt regulator that can sink up to 100mA, adjustable from 2.5V to 36V. you could think of it as an adjustable zener, some distant cousin of the LM317
>>unless you mean swinging highly negative in which case absolute increase
>the sense + terminal swings in the - direction. you may as well just make the freewheel diode a permanent part of the instrument. reverse leakage of the diode is equal to a tiny fraction of an LSB. try that circuit with a 1N4148 and see
>>swinging too severely
>the inductor resists change in current. at the instant the force + terminal is disconnected, the inductor will be pushing a current equal to and in the same direction as the test current. the load path through which that current is forced determines the voltage. without the freewheel diode, that path probably involves the inst amp substrate and random diodes throughout the device, if not the 3.3V rail and other devices on it
Contribuyendo!
Jimmie
Loopy

[Anonymous No.1640991]

>>1640967
>an adjustable zener
That actually sounds really useful for things like capacitive dropper supplies. Do they have a sharper cutoff at low voltages than a ~5V zener? Looks like it, I wonder how they get such a sharp cutoff?

[Anonymous No.1641000]

>>1640991
>how they get such a sharp cutoff?
They use electronic circuitry.

[Anonymous No.1641001]

>>1641000
Too bad that means they can't be used for higher voltages.
On a similar note, are there linear regulators I can use on rectified 240V mains to drop the output by a few volts for ripple-rejection reasons? I was wanting to use rectified mains for a condenser mic bias.

[Anonymous No.1641002]

>>1640707
>>1640788
I'm seeing people connect the LED-strips directly to batteries that match the voltage. What's stopping me from doing that?

https://www.amazon.co.uk/XTPower%C2%AE-XT-20000QC3-Power-Bank-connection/dp/B07PY8516W/ref=sr_1_4?keywords=24v+battery&qid=1562090028&s=gateway&sr=8-4

This even has the exact plug. I can unplug the strip from the wallplug.

>>1640753
0.8. So it would have to 1.6 to run two. I'd have to get 1.6A from the start and reduce it to 0.8 with a resistor to run one light?

[Anonymous No.1641003]

>>1641001
Capacitance multiplier.

[Anonymous No.1641004]

>>1641002
>What's stopping me from doing that
Nothing, except for the voltage fluctuations, and the lack of a dimmer module, assuming you want that, and assuming that last LED strip you posted had the mains power supply built into the dimmer module. For on/off operation, just putting a simple switch inline with the plug and no dimmer unit would afford you a perfectly functional system if you spec your battery properly, though using an LED unit that had no resistors and a constant-current switching supply would likely be more efficient.

[Anonymous No.1641005]

>>1640942
>the knee has already been passed
This graph starts at 0.4V/10µA and shows almost 4 decades of exponential Vf/If relation. You could extend the graph down to Vf=0V and still find no 'knee'. Above about 100mA you see the influence of the series resistance.

[Anonymous No.1641011]

Note to self: li-ion batteries can be easily punctured by component legs sticking out of a pcb.

[Anonymous No.1641012]

>>1641004
Ah, the dimming..
https://www.amazon.co.uk/LIGHTEU%C2%AE-Controller-Original-Milight-fut043/dp/B07J6RC4BB/ref=sr_1_58_sspa?keywords=24v+led+dimmer+dc&qid=1562146913&s=gateway&sr=8-58-spons&psc=1

Then something like this in between the battery and strip.
It outputs 6A though which is good since I have 2 strips I'd like to power one by one and together.
I calculated wrong earlier, the original powersupply outputs 1.25A. So I need a resistor adapter to reduce by 4.75A and another for 3.5A?

[Anonymous No.1641018]

>>1640885
>Should there be a knee
The knee only appears in a lin-lin coordinate sytem. But where exactly is it?

[Anonymous No.1641020]

>>1641018
somewhere near/below the rated power consumption of the diode, I'd assume

[Anonymous No.1641021]

>>1641011
I would prefer a flat LiPo cell for that.

[Anonymous No.1641026]

>>1640967
>the inductor resists change in current
I know this
Which is why I brought about the whole discussion of protecting the inputs in the first place

[Anonymous No.1641036]

>>1640840
How much experience in electronics do you have?

[Anonymous No.1641038]

>>1641020
Do diodes have a rated power consumption? I've never seen that specified in a data sheet.

[Anonymous No.1641041]

>>1641038
They usually give max current because the voltage drop is always about the same dude.

[Anonymous No.1641044]

>>1641018
where dy/dx=1

[Anonymous No.1641101]

something stupid that I can't wrap my head around despite working with electronics for 2 years...

say I have a desk fan rated at 12 volts, and I hook it up to a raspberry pi that supplies 5 volts.
Will any harm come of this? I.E., the fan won't, say, try to pull more current than the 5 volt supply can supply to try and run at 12 volts from the pi and fry it, right? The fan will just putt along at a lower speed?

[Anonymous No.1641102]

>>1641101
>desk fan
case fan

[Anonymous No.1641106]

I want to get into robotics as a career, and Im now thinking I would have liked mechanical more than electronics in which I have graduated.
Anyway, should I go for Mtech in Control or just apply for shitty jobs in industries as I have a shitty average GPA? The university in my country conducts a test (which I can easily clear, I think) for admission in PG and doesnt look too much into GPA.
This is more of an advice post, sorry for sounding extremely stupid but Im lost here.

[Anonymous No.1641113]

>>1641005
Wait your graph is a straight line from 0.4 to 0.8 on a logarithmic scale, so it is exponential? So the knee must be there somewhere.

[Anonymous No.1641114]

>>1641044
but it is e^x. dy/dx = x everywhere.

[Anonymous No.1641115]

>>1641114
i repeated what the pic said. but i mean to say exp(x).

[Anonymous No.1641120]

>>1641044
Very good, a dimensionless 45° tangent, right in the middle. Can you apply that to the p-n junction of a diode? Hint: dIf/dVf=1S

[Anonymous No.1641124]

>>1641114
So x=1V?

[Anonymous No.1641125]

So it just occurred to me that the voltage rating for a diode is necessarily a REVERSE voltage. So if you are only going to use your diode in a forward direction in a DC circuit, you can apply a million volt to it? All that matters is the forward current not voltage?

[Anonymous No.1641126]

>>1641125
yes that's how a diode works, give it a shot

[Anonymous No.1641127]

>>1641018
> But where exactly is it?
It isn't exactly anywhere. The knee is where the current goes from "negligible" to "significant", which is subjective.

This is why the figure given for the forward voltage of a silicon P-N junction vary between 0.6V and 0.8V. The voltage at which a diode conducts depends entirely upon how you define "conducts".

[Anonymous No.1641131]

sup /Ω/
requesting V=IR Homer

[Anonymous No.1641134]

>>1640964
- use a different PSU for your arduino and your fan?
- put a LARGE cap to filter the PSU output?

[Anonymous No.1641137]

>>1640885
>but the graph looks logarithmic all the way from 0.6 to 1.8V
answering my own question, after taking a closer look that logarithmic graph can be misleading. Here, this part looks perfectly linear which would be exponential on a linear scale. So the knee is there somewhere. And after that it becomes logarithmic on that graph which means it is linear.

[Anonymous No.1641138]

>>1641101
>say I have a desk fan rated at 12 volts, and I hook it up to a raspberry pi that supplies 5 volts.
The RPi is never going to supply enough current (amps) to get the fan spinning. You would be roughly shorting one of your GPIO pins to ground. If you are lucky, the fan will have enough internal resistance that you won't blow the GPIO circuitry inside the RPi.

If you had 5v and enough amps, then yes, the fan would spin but slower.

If you want to control a fan with a 5v GPIO, get a transistor that can handle the current you need. For example, the BD139 used here : https://www.electroschematics.com/9540/arduino-fan-speed-controlled-temperature/

[Anonymous No.1641139]

>>1641138
Got it, that's exactly what I was worried about. I fried my first pi years ago by doing just that and now I know why.
I've already wired up a transistor+PWM circuit to properly control a fan for my pi 4 when it gets here.
Thanks for the tip!

[Anonymous No.1641140]

>>1641127
Why "between 0.6V and 0.8V" if it is all just a subjective opinion? Why not between 0.1V and 1V? Someone had a good idea about locating the (fictional) knee.

[Anonymous No.1641141]

>>1641137
Ok, here I plotted the same datapoints on a linear graph. Here is the knee. Now my autism is 100% satisfied.

[Anonymous No.1641145]

>>1641139
Does the RPi have hardware PWM on its GPIO ?

[Anonymous No.1641146]

>>1641145
Now that you mention it, I believe it does. In that case I'll just use the transistor.

[Anonymous No.1641155]

>>1641140
Well the 'knee' subjectively (visually) implies the graph changes direction from < 45 to > 45 slope. Which happens at the point where dy/dx =1. Since the diode equation is not strictly e^x, it can be approximated as I = Is x exp (V/Vt). where Is = 7 x 10^-13A and Vt = 25mV. So the derivative is 7e^(40x) / 250000000000. We need to solve for x when y=1.
So it works out to be
(ln(1) - ln(7/250000000000))/40
~ .607V.

[Anonymous No.1641161]

>>1641155
Oh and that Is can vary within 2-3 orders of magnitude depending on the manufacturing technology. The lower it is, the higher the resulting V will be. .6 to .8 roughly.

[Anonymous No.1641170]

>>1641011
post video

>>1641026
right. and the most direct protection against induced emf under your application conditions is that freewheel diode immediately across the input. stays well out of the way of the small normal voltages of concern, keeps fault voltages well south of damaging levels

>>1640840
you, fellow fatguy anon, are a 100W processor, just bigger. this information is useful to help you dimension your cooling system by analogy to performance PC water cooling system standards

>>1641106
>asks for career /adv/ice
>doesn't specify country
/ohm/ RULE 2

>>1641145
check the bcm hardware libraries to see
or, better yet, write a kernel driver and device tree fragment and make yourself employable

[Anonymous No.1641182]

>>1641170
>make yourself employable
oof

[Anonymous No.1641187]

>>1640840
A small compressor system could probably give you 5x the cooling per Watt as a Peltier. That starts being competitive with ice.

A Peltier might get COP 2, so LiPo might give you 1.5MJ/kg of cooling. A Kg of ice gives you 3 MJ/kg. With ice you don't need forced air cooling and a heatsink either.

[Anonymous No.1641190]

>>1641187
>hauling around a refrigerator
>t.Baron Vladimir Harkonnen

[Anonymous No.1641191]

>>1641155
>solve for x when y=1
x in volt and y in ampere?

[Anonymous No.1641194]

>>1641191
that is a derivative dy/dx so we need to find a point x (voltage) where dI/dV = 1.

[Anonymous No.1641198]

>>1641190
It's not like you want to strap LiPo packs to your body, so with a battery system you will have a case any. You can get cheap compressors the size of a soda can.

https://www.aliexpress.com/item/32841083743.html

[Anonymous No.1641201]

>>1641194
but dI/dV is not dimensionless, it is a conductance, right?

[Anonymous No.1641203]

>>1641201
right

[Anonymous No.1641207]

>>1641203
Thank you. I'm trying to understand all this. Does that mean that the knee is supposed to be where the dynamic conductance of the diode is one siemens and the dynamic resistance is one ohm?

[Anonymous No.1641214]

>>1641187
Thanks fren, I know they are super inefficient and all the jazz. I really only want to use one because of the size. How small do those compressors get? I don't really have the capacity for more than a heat sink and a battery.

[Anonymous No.1641222]

>>1641214
>https://www.aliexpress.com/item/32841083743.html

It's really hard to compete with ice though. For a small capacity systems you can just put lightly isolated icepacks in a shirt and be done with it.

[Anonymous No.1641235]

>>1641222
filthy casual

[Anonymous No.1641274]

>>1641207
Yeah, I didn't think about it from that perspective but you are right, the units are transconductance or dynamic conductance/resistance. That reminded me of the vacuum tube calculations. Here is the venerable 12ax7 that I was researching not too long ago. It is a totally different application but the same concept.

>the knee is supposed to be
I don't think there is a strong definition or any particular importance of that knee in the forward region. For example, Sedra and Smith refers to the reverse breakdown as the 'knee' where the graph drops down sharply in the reverse bias region. I don't think that term is used in the forward bias region in that book. They just talk about a 'cut-in' voltage and a transition from 'zero current' to 'fully conducting' which is a relative term.

[Anonymous No.1641345]

>>1641170
>damaging voltages
so you're saying I should just have a built-in low leakage freewheeling diode?

[Anonymous No.1641348]

>>1641274
The Vf knee is certainly not a well-defined term but rd=1ohm looks like a convenient reference.

I'm reading http://www.kennethkuhn.com/students/ee351/diode_characteristics.pdf
Using rd=n*Vt/I -> I=n*Vt/rd I get a current of about 50mA and in the graph posted earlier this points to a forward voltage between 0.8 and 0.9V.

Vf=n*Vt*ln(I/Is+1) yields about 0.8V using the 1N4148 spice data Is=4.352e-9A, n=1.906 and 26mV for Vt, kT/q at 300K. I think I will leave it at that. Thanks for your replies.

[Anonymous No.1641357]

>>1641222
>>1641198
>You can get cheap compressors the size of a soda can.
>220V/50Hz
>275W

[Anonymous No.1641360]

>>1641345
correct. even a standard-leakage 1N4148 is rated to handle up to 150mA or 75V continuous
I am still assuming you're using a test current around 25mA. if you go significantly than this, everything's null and void and we'll have to start again

[Anonymous No.1641373]

Im not sure if this thread or the arduino thread is the right one for avr programming so if you guys want me to post there I will, or I might do both.

Essentially there are two github projects I am trying to combine. From one project I need the i2c stuff. Which comes in two files modified for my chip
>twi.h
>twi.c
I added these two files into the other projects folder. And included them in the driver file for the program. Fixed the red error messages the compiler spit out but when it tries to make I still get unreferenced function errors. Not in red though.
Using linux avr gcc to complie if that helps.

[Anonymous No.1641374]

>>1641373
post errors
on >>>/diy/ag

[Anonymous No.1641377]

>>1641357
>Can not deliver to United States
fucking antisemites

[Anonymous No.1641382]

>>1641373
did you build the object file and passed it to your compiler it when you compile the binary?

[Anonymous No.1641395]

>>1641382
No neither project had any obj files. When adding just twi.h and twi.c file to the folder I included them in the header of the driver. Did they need to be included somewhere in the makefile?

[Anonymous No.1641412]

>>1641382
>>1641373
I figured it out. Or at least got it to compile. Its been so long since Ive done stuff like this I messed up the makefile.

[Anonymous No.1641429]

>>1641360
no my test current was always 100mA
But I can tell you're responding to multiple people though so its no prob lol
I've thought of how the differential output simplifies voltage requirements too so i may go that route now

[Anonymous No.1641455]

>>1641429
>100mA
hrm. I don't like pushing the regulator all the way to its limit, maybe swap it out for a series pair of 1N4001s forward-biased, still primed by the 1k. those two diodes generate a sufficient ~1.25V offset from ground for the freewheel diode to keep the inputs in bounds, while allowing more +-side headroom. that would produce a small common-mode offset that varies with DUT resistance but the inst amp will reject it at 80dB or more
I recommend you run the current source and the diff amp from the same rail, which implies running the ADC from the same rail. the easy way out is a 5V diff-input ADC, if you can find one suitable. the next easier way out is a 3.3V wall wart. the hard way out is to put a 3.3V regulator on board, and since diode leakage and inst amp parameters degrade significantly over temperature vs. at 25°C, you get to choose between keeping a linear reg cool or keeping a buck's oscillations from coupling into the rest of your circuit

[Anonymous No.1641543]

>>1641134
what is a large cap? what is a smol cap? people liberally use those words but they could mean anything. 1pf? 1mf? 1f?
I have some 4F caps coming on a ship from ricelands so i could try those

[Anonymous No.1641559]

>>1641543
if the power supply is in fact glitching, 100-1000µF might be enough to tide the duino over. too much would look like a dead short to a chinky supply and it might not even start up, in any case, the closer to the duino, the better
if it's something else, like inductive or capacitive coupling to your switch or duino, things get more complicated. proper earthing can help, especially if the 0V output of the supply is connected to proper earth

[Anonymous No.1641560]

>>1641170
>doesn't specify country
India

[Anonymous No.1641565]

>>1641559
>1000µF
Sounds like a bit large, especially compared to the amount of power being used by the duino itself. 100µ is reasonable however. More input filtration on the PSU is likely also a good idea, if possible.
Putting them on different circuits would also help.

[Anonymous No.1641585]

>>1641559
Well then i'm dun goofd because the chinky power soruce already has a 1k uf cap on the output
I guess i will try a bigger one and if the source thinks it's a short i can add a resistor so it charges at last 500ma tops

[Anonymous No.1641591]

this is pretty comfy

just wish you could import netlists

[Anonymous No.1641595]

>>1641585
>k uF

[Anonymous No.1641603]

>>1641595
k is a shorthand for kilo meaning 1000

[Anonymous No.1641606]

How is amperage reduced without changing the voltage?

[Anonymous No.1641608]

>>1641606
not in this universe buckaroo

[Anonymous No.1641609]

>>1641591
Does it also do stripboard? Also what would you use a netlist for? Converting to a proper KiCAD layout?

>>1641606
By increasing the resistance, obviously.

[Anonymous No.1641610]

>>1641609
>By increasing the resistance, obviously.
and what pray tell does the resistor drop when you send current through it?

[Anonymous No.1641611]

>>1641608
That's what I figured.
Then how the fuck do I power something that has needs low amperage when the power supply only comes in too high amperage?

[Anonymous No.1641612]

>>1641611
You can still drop voltage with resistors

You have to do some math.
V = IR
So if you have 5V power source and have a led that draws 0.02A at 2V you do R = 3 / 0.02 = 150ohm resistor
3 because you need to drop 3 volts to get 2v at 20ma for that led

[Anonymous No.1641614]

>>1641610
With a variable resistor across a constant-voltage supply, it drops the same voltage regardless of resistance. If it's across a current source, or is in series with another resistor, that doesn't apply.

[Anonymous No.1641615]

>>1641609
Does all kinds of boards.

>Converting to a proper KiCAD layout?
No (it does seem to have export for netlists), I just would like it to keep track of all required connections.

[Anonymous No.1641625]

>>1641611
Your mains socket can supply 10 amps but your lightbulb only needs 1 amp. Will it explode?

[Anonymous No.1641633]

>>1641625
sometimes

[Anonymous No.1641635]

>>1641625
It will if it is a led

[Anonymous No.1641659]

>>1641585
I tried to add the cap anyway, so i am curious to see if it will make any difference

[Anonymous No.1641675]

Guys I need help ASAP.
What happens when you connect N thyristors or MOSfets or IGBTs in parallel?
Ok I get it, the input current is divided by N right?
What else should I think here about?

[Anonymous No.1641683]

>>1641675
mosfets can usually be safely paralleled. their resistance increases with temperature so the load current will balance roughly evenly between the fets. apply a safety factor. if you're switching them quickly (maybe >10khz) you can have a transient situation where only one fet is on and taking the entire load current too often which will cook it.

if you need high power and you're not making an amp, don't use bjts. i can't speak for scrs, but google can.

[Anonymous No.1641690]

>>1641595

[Anonymous No.1641692]

>>1641690
How much kmAh is that?

[Anonymous No.1641697]

>>1641692
depends on the voltage dipstick

[Anonymous No.1641699]

>>1641697
both depend on voltage

[Anonymous No.1641704]

>>1641699
>>1641697
it says the cap has 35 volts in it right on the label dumbfucks

[Anonymous No.1641707]

>>1641595
>>1641603
>>1641690
>>1641692
A local FM radio station has a spot where the announcer proudly claims they are a fifty million milliwatt power-house.

[Anonymous No.1641709]

/sci/ is cancer so I thought I'd ask here. I still don't truly understand voltage as the difference of potentials since I don't really understand the potential (hurr durr work required to move stuff). I know it is roughly about charges and distance. For example a capacitor has two parameters Voltage and capacitance. I understand capacitance is how much charge in Coulombs it can store. So for higher capacitance the plates would need to be larger. But how does the voltage rating affect the construction of a capacitor? The plates need to be closer to each other? What about a battery? What does it mean a battery supplies 1.5V? Is that also about the distance between the 'positive and negative sides'?

[Anonymous No.1641715]

>>1641709
hopefully you get a decent reply, but your battery question is treading into electrochemistry which hobbyists and EE students don't really get into.

capacitance increases as you make your parallel plates larger or closer together. however the maximum voltage decreases as the plates get closer together, because at a certain voltage the material between the plates will change state to be conductive, which defeats the purpose of the capacitor and can also destroy it due to self-heating from the resultant flow of current. so you want to make your parallel plates as close together as you can while meeting your desired voltage rating. you can then make the plates as large as you need.

also capacitance is in farads. charge is 1/2 farads * volts^2.

[Anonymous No.1641716]

I have some spare speakers (as well as ones attached to and cd player) and a beaglebone. I want to create a speaker that I can put on my bookshelf and connect via bluetooth or load a bunch of songs onto a usb and control through the phone.
Is this possible? I don't even know how to get started with this.

[Anonymous No.1641722]

>>1641716
I'd use a 2$ bluetooth audio module instead of wasting a beaglebone on that

[Anonymous No.1641723]

>>1641715
Thanks, I agree the battery is trickier. As for the capacitor, I still don't quite understand what parameter controls the maximum Voltage and what the means in terms of the physics of the capacitor. I know V is analogous to pressure. So maybe it is the ability of the dielectric layer to withstand electrical 'pressure'??

[Anonymous No.1641725]

>>1641723
>maybe it is the ability of the dielectric layer to withstand electrical 'pressure'??
yes, in the sense that a stronger metal lets you make a fluid pipe thinner. but the maximum pressure of a pipe is most fundamentally determined by how thick its wall is. likewise the thickness of the dielectric layer (just between the plates, generally) determines a capacitor's maximum voltage.

[Anonymous No.1641728]

>>1641709
>I don't really understand the potential
Potential is energy divided by its 'medium', like mass for gravitational potential (m*g*h --> g*h) or charge for electric potential (q*V --> V).

[Anonymous No.1641757]

>>1641709
> I understand capacitance is how much charge in Coulombs it can store.
Capacitance is coulombs per volt. Charge stored is capacitance times voltage.

> So for higher capacitance the plates would need to be larger.
Or closer together. For a parallel-plate capacitor, capacitance is proportional to the plate area and inversely proportional to the distance between plates.

> But how does the voltage rating affect the construction of a capacitor?
For a given dielectric material, a higher maximum voltage requires a thicker dielectric, so plates farther apart. Which reduces the capacitance for a given area. For a given volume, it also reduces the plate area. The maximum stored energy (=(1/2)*C*Vmax^2) remains constant for a given volume.

> What does it mean a battery supplies 1.5V? Is that also about the distance between the 'positive and negative sides'?
Battery voltage varies with chemistry. Most primary (non-rechargeable) cells are 1.5V. Lead-acid, NiMH and NiCd secondary (rechargeable) cells are 1.2V. Li-Ion cells are ~3.7V, LiFePO4 are 3.2V. Plate thickness affects the trade-off between maximum current and energy capacity (e.g. for lead-acid, car batteries are designed for high current so have thicker plates than batteries designed for a continuous load).

[Anonymous No.1641760]

>>1641709
/sci/fag here, capacitance and batteries are fundamentally different. In a capacitor the energy is stored in the medium in between the two plates, when you charge a capacitor you use an external voltage to polarise the medium, this is why some higher dielectric potential leads to more stored energy as the material polarises "harder", think of a spring, a stiffer spring stores more energy with the same compression than a loose spring, voltage in a capacitor is equivalent to the amount of compression in a spring. Voltage rating comes from the fact that a certain medium can only withstand certain voltage differential before the current arcs through, IIRC dry air was 1kV/cm or something.

Batteries on the other hand store energy in their chemical potential, the chemistry class example of a zinc rod and a copper rod sticked into a lemon for instance, the electrons in the zinc want to go over to the copper rod as its a more pure metal, this leads to voltage between the rods that comes from the difference in nobility between the metals. Google standard electrode potential for more information

[Anonymous No.1641762]

>>1641412
>Its been so long since Ive done stuff like this I messed up the makefile
Makefiles should have been extinct a long time ago

Change my mind

[Anonymous No.1641763]

>>1641762
you don't need them. just write asm in one big text file with no comments like real men.

[Anonymous No.1641764]

Does this mean that A0 is in a dont care state prior to D1? As in, can I drive A0 high or low before starting the SPI transfer?

[Anonymous No.1641780]

>>1641764
It means that after you pull the CS low it doesn't matter what you do to A0

[Anonymous No.1641791]

>>1641757
>>1641760
Thanks anons. I am trying to wrap my mind around all of that. So the capacitance is defined in terms of Charge AND Voltage... And a capacitor also has a maximum voltage rating.

I am just trying to visualize charging a capacitor as a flow of electrons, i.e. I imagine a bunch of little balls are being pushed into a sack until a full 'capacity' is reached.

So I think of a 'capacity' in layman's terms as the ability to store 'stuff', like balls in a sack. But the meaning of Voltage escapes me in this case. Is it as if those balls had different levels of energy? If it is related to potential energy, can we think of the balls being dropped from a certain height that would represent a higher potential? So if you throw a bunch of balls in a sack, its construction should account for both how many balls it can store and how hard you can throw them?

[Anonymous No.1641792]

>>1641715
>charge is 1/2 farads * volts^2
C*V^2/2 is the energy stored in a capacitor, the stored charge is C*V.

[Anonymous No.1641793]

>>1641792
yeah i is dumb

[Anonymous No.1641796]

>>1641792
>stored charge is C*V.
This is so confusing. The unit of charge is Coulomb. The carrier of charge is an electron, right? S 1 Coulomb of charge is just a gazillion of electrons. What does voltage have to do with that?

[Anonymous No.1641802]

>>1641791
Not quite, a capacitor never gets full, the maximum voltage rating doesn't exist in an ideal capacitor and is only due to constraints of real materials. Capacitance is the ratio between the amount of charge stored in the capacitor and the voltage between the plates.

Consider a cylindrical water reservoir, the equivalent of charge here is the amount of water, and the voltage equivalent is the water level. A cylinder with a larger radius needs to take in more water to get the same water level as a smaller cylinder, so a larger cylinder has higher water "capacitance". These cylinders are also ideally infinitely tall.

>>1641796
To extend the hydraulic analogy, the capacitance or area of the cylinder times voltage or water level gives you the volume of water inside the cylinder, aka charge.

also yes hydraulic analogies are bad

[Anonymous No.1641804]

>>1641802
Oh, so the 'level' can be thought of as a 'height' of an object analogous to the gravity and potential energy?

[Anonymous No.1641851]

So i can put a snubber across contacts for some ac motor like a fan to handle the current surge, but what happens if you use a snubber for some plain old resistive load, like for example computer PSU, will it have any effect on it?
(I want to put it into my extension cord and connect all kinds of shit to it, not just ac motors so i need to be sure the snubber won't fuck with AC devices that aren't motors)

[Anonymous No.1641854]

>>1641659
>>1641851
Also still doesn't work fucking shit, i am now absolutely sure the relay is generating some fucking EMP tier shit, because this new power source isn't like the cheap shit one, the chinks spared no expenses at all, all those y caps and and a second transformer and shit i have no idea why, but it's there so it's definitely not a power problem, yet both of the ics reset, so it must be the fucking relay causing it, so i am hoping the snubber will solve that

[Anonymous No.1641857]

>>1641854
Yes, this little baby will solve all my problems
And if not i am going to neck myself because i have spent forever on this retarded project already

[Anonymous No.1641881]

>>1641796
>unit of charge is Coulomb
Coulomb is just a given name, the basic unit of charge is As or ampere second and volt*ampere*second is watt*second and the Ws is a unit of energy, also called joule.

[Anonymous No.1641896]

i'm sizing a tvs diode with a 68 ohm limiting resistor in series on the mains. is there a standard model for mains transients similar to the HBM that i can use?

[Anonymous No.1641911]

>>1641896
found a nice table in an9769

[Anonymous No.1641945]

>>1641881
but the Coulomb is a quantity while Ampere is a rate of change of charge and it is defined as Coulomb per sec.

[Anonymous No.1642016]

>>1641945
The ampere is not defined that way. A current in a wire does not change the charge, it only does so if applied to something that can store charge, like a capacitor. The coulomb is not a base unit but both the ampere and the second are.

Just as an aside: There are notation rules regarding physical quantities. The name of a unit is written in lower case (unless first word of a sentence). If you write newton you mean the unit of force, if you write Newton you mean the person. The symbols of units are upper case only if the name of the unit points to a related person. Example newton meter (Nm), ampere second (As), watt second (Ws), joule (J). One exception: the liter or litre (L).

[Anonymous No.1642040]

>>1641854
>fucking EMP
Have you tried a capacitor across the coil of the relay?

[Anonymous No.1642089]

>>1641945
It more comes down to the fact that a volt is one joule per coulomb, with the volt roughly being defined a while before anyone knew the charge of the electron, if memory serves me correctly. Arguing for 1C = 1e might as well be arguing for planck units for everything, which just isn't very practical.
But if we do use "natural" units for everything, I vote that the magnetic permeability and electric permittivity be set to unity, and that G is set to 1/(4π).

>>1642016
Just to make the units nicer, I suggest that the coulomb be taken as the base unit, not the ampere. Less dimensions = easier, just like the metre and second. Also the candela is a bullshit unit, we don't have some unit with the standardisation of the human hearing curve in there, no reason to have the human vision curve shoved in there like it's some fundamental property of the universe. As far as physics is concerned, radiant intensity is all we ever need, that medsci lot can define their own base units.

[Anonymous No.1642107]

Hey /ohm/. Grug here.

Is there any way I can learn how to diagnose failed electronics without a degree in electrical engineering? I need a set of heuristics for figuring out what part is blown on a board so's I can replace it.

[Anonymous No.1642108]

>>1642107
Big Clive and EEVblog have a fair few troubleshooting videos that might help, there's also a book in the OP that sounds right.

[Anonymous No.1642110]

>>1642108
>so grug i don't even read the OP
Thanks anon.

[Anonymous No.1642119]

>>1641762
> Change my mind
You can't reason someone out of a position they didn't reason themselves into.

You're the one suggesting that the entire profession has it wrong, so it's up to you to suggest an alternative.

[Anonymous No.1642127]

>>1642089
> Just to make the units nicer, I suggest that the coulomb be taken as the base unit, not the ampere.
The coulomb is the base unit, as of May 2019. The coulomb is defined such that the elementary charge is 1.602176634e-19 coulombs (i.e. 1 C = 10^28 / 1602176634 elementary charges, but that doesn't have a finite decimal representation).

The ampere remained the base unit for so long because it's much easier to construct a physical standard (current balance).

[Anonymous No.1642140]

where can I get rotary switches cheap for high end audio applications frens?

[Anonymous No.1642143]

>>1642140
Seconding this, rotary switches are great but ali doesn't seem to sell the 5+ position ones.

[Anonymous No.1642152]

>>1642143
>Seconding this, rotary switches are great but ali doesn't seem to sell the 5+ position ones.

Built a Tektronics LA2A tube compressor and I really don't want to spend $100 on rotary switches.

[Anonymous No.1642155]

>>1642140
>>1642143
6-11 position switches are hard to find, it is true. 12 position switches, otoh, are everywhere. I even saw a 4P5T rotary band switch while scrolling

>>1642119
I think that anon wants to do all his project dependency tracking with systemd

[Anonymous No.1642157]

>>1642155
>12 position switches, otoh, are everywhere
Shit, since when? I searched for them a few years ago and found nothing, and ended up buying 10 of them at ~$4 each locally.

[Anonymous No.1642162]

>>1642157
since before I checked a few minutes ago

[Anonymous No.1642185]

What kind of diodes should I use for a bridge rectifier connected to 120 AC mains? I want to wrap a fuckhuge electromagnet, and perform other HV experiments.

[Anonymous No.1642195]

>>1642185
Diodes that can handle the current required, both peak and continuous. For that you'll need to know the inductance and ESR of your electromagnet, and the capacitance of your filtration caps. Better get some beefy caps, like these:
https://www.aliexpress.com/item/32282186340.html (450V 1mF, the closer you can get the voltage rating to your rectified mains voltage the better).
If you go without any filtration capacitors, you won't need to worry about peak current. Or more correctly, peak charge or energy or whatever shorting a cap would cause you to care about within a diode.

[Anonymous No.1642218]

>>1641722
I was thinking of making a sort jukebox out of the beaglebone; with a screen later. The beaglebone was for free so I don't feel like I'm wasting it.

[Anonymous No.1642230]

>>1642127
>The coulomb is the base unit
The seven base units have not changed, only the metrological realisation. One coulomb is still one ampere second.

[Anonymous No.1642231]

>>1642040
it's relay in a ic ready package so it comes with a flyback diode built in and all that jazz

[Anonymous No.1642244]

>>1642231
That doesn't matter, it's the magnetic pulse produced by the coil that could cause the effect.

[Anonymous No.1642245]

>>1642244
And would the cap across the coil prevent the emp? if so what capacitance are we talking here?

When the snubbers arrive i will try if the will solve the problem, but that will be several weeks from now. The only other solution i can think of is to wrap the IC in a tin foild to shield it from the emp, but that is kind of gay

[Anonymous No.1642249]

>>1642245
>what capacitance
Start small, less than a µF.

[Anonymous No.1642261]

>>1641131
>sup /Ω/
>requesting V=IR Homer
anyone?

[Anonymous No.1642311]

Hello famalang, I'm nearly done with a pic datalogger thing that stores data in a EEPROM IC. Now how would I transfer the data to a computer? It does not have a serial port. Is it feasible to interface it with usb? How (or where to look) would I do that, is it feasible?

[Anonymous No.1642315]

>>1642311
>It does not have a serial port.
The PIC should at least have UART or be able to bitbang it. You can use something like a MAX232 to convert it to RS232 voltage levels to give it a serial port.
Or you can use an USB-TTL chip like the FT232 or the chink CH340 to allow it serial communication over USB.

[Anonymous No.1642325]

>>1642230
man i so want to sit on that committee or whatever you call it and set those values and publish them. imagine casually mentioning to your friends and relatives over a beer that you are working on redefining the second. fucking awesome. a perfect job for a NEET. plenty of free time plus a lead ass is all you need. also you'd need a big bag for electrons and a scale to weigh them.

[Anonymous No.1642330]

>>1642315
The computer has no serial port. Do you know any alternatives that do not involve aditional ICs? I'm just starting with mplab and it seems huge, doesn't microchip has a usb framework for crappy pics?

[Anonymous No.1642336]

>>1642330
>doesn't microchip has a usb framework for crappy pics?
It is possible to bitbang low-speed USB - V-USB does that but it's only ported to AVRs.
I have no idea if something like that exists for PICs alredy.

Another way for simple serial communication with a PC would be through the PC's soundcard:
https://www.swharden.com/wp/2011-07-09-sound-card-microcontrollerpc-communication/

[Anonymous No.1642338]

>>1642127
i am not disagreeing since i don't even know anything, but it is interesting
>The ampere remained the base unit
which is basically a rate of change, just like velocity? so we could define distance as speed multiplied by time? so for example we can say that 12.27m/sec is one Bolt. then we can define a certain base distance as one bolt sec. or simply bs.

[Anonymous No.1642357]

>>1642325
Want to meet the commitee? Go to
https://www.nist.gov/si-redefinition/turning-point-humanity-redefining-worlds-measurement-system
scroll down and watch the "We Did It!" video.

[Anonymous No.1642410]

why isn't there a youtube video showcasing LEDs with different millicandela values? i have no idea if what i'm buying will be too dim or too bright.

[Anonymous No.1642412]

>>1642410
just get them in the shop to turn the light on anon

[Anonymous No.1642414]

>>1642195
Thanks. I want to build a magnetizer/demagnetizer for my tools. It can be down and dirty. I just need to be able to put a high-gauss field on screwdrivers and the like.

[Anonymous No.1642416]

>>1642414
Have you got a spectrum analizer anon ,if not just buy them

[Anonymous No.1642421]

>>1642325
People on those committees are published experts in their fields. NIST physicists do a lot of work.

It IS fun, however. My dad loved it so much that he didn't retire willingly. Mom made him.

[Anonymous No.1642422]

I'm looking for terminals to solder down on custom pcbs I will be designing, to mate with an existing device with male terminals.

So I would like Female, Through-Hole, vertical 3 Pion 3,5mm pitch connectors.

I don't want to use straight Pin rows, since I would like to save the assembly time on screwing all the terminals.

Anyone got anything specific I am looking for? Am I looking for the wrong thing?

[Anonymous No.1642442]

>>1642416
Do I really need one for that?

[Anonymous No.1642444]

>>1642442
Yeah, an dont even try this shyte , just buy
You have No knowledge on this an will Kill self

[Anonymous No.1642519]

Working on a simple CMOS sequencer circuit for a traffic light. It _should_ show a repeating sequence of red -> green -> flashing green. The circuit works in Logisim, so I probably miswired something...
Current parts are:
- CD4093 NAND oscillator
- CD4027 dual JK flip-flop
- CD4017 counter
- 74HC74 dual D flip-flop

[Anonymous No.1642521]

>>1642311
>no part numbers
/ohm/ RULE 2
a CH330N only costs like 30 cents and is babby-tier easy to use. some FTDI chips will also do SPI over USB but it sounds like a PITA to try

>>1642338
>he thinks he's Don Knuth

[Anonymous No.1642529]

>>1642519
>I miswired something
nice blog
show video game screenshot so we can tell you where you neglected to account for real propagation delays. then show intermediate schematic you should have drawn for pin assignment and assembly

>>1642422
those are not the connectors you're looking for. they're proprietary to the screw blocks
>3.5mm pitch
y tho
and how mechanical (i.e. load-bearing) are these terminals going to be? are the boards going to be mechanically supported by something else?
look into AMP/Tyco Electronics Mate-N-Lok series. Molex had a series called Mini-Fit or something like that which may also have something useful for you. also, generally, search for board-to-board connectors

[Anonymous No.1642532]

>>1642414
get a power transformer that works on the voltage supplied by your utility
remove all the I plates and organize with all the E plates on one side of the core
/diy/ a case and switch with power cord and you're done

[Anonymous No.1642545]

>>1642519
post schematic

>>1642529
>intermediate schematic you should have drawn for pin assignment and assembly
lol. Who does that? Other than babby tier tutorials, what purpose would that serve?

[joldberg No.1642557]

hey /ohm/, trying to build a guitar amplifier and am making an assumption for parts to use. i’m trying to do it with a small
amount of electronics knowledge. so far im looking at a bipolar transistor and from the way it works an npn junction might work. i dont think it will since the collector would be connected to like an AA 1.5V and the base would be connected to a pin of the guitar output. i made 2 configurations for the idea. i think config 2 will work but not sure about where to put the negative terminal of the batteries. so i just put them together.

[joldberg No.1642558]

>>1642557
not sure how to flip phone photos

[Anonymous No.1642559]

>>1642325
>big bag for electrons
At your next beer session you could introduce the definition of the Imperial Fuckton as the force between two moles of electrons at a distance of 1 yard. Exactly 1e20 N. Or is it.

[Anonymous No.1642561]

>>1642545
someone who doesn't leave two inputs on their CD4093 open

[Anonymous No.1642562]

>>1642558
ftfy

[Anonymous No.1642588]

>>1642557
wew lad

[Anonymous No.1642590]

>>1642557
looks awesome
do a vocaroo upload so we can hear how it sounds

[Anonymous No.1642598]

>>1642561
floating inputs are the spice of life

[Anonymous No.1642600]

I wonder if my case falls under the paralysis by analysis. I wanted to build something and I was thinking over some circuit design and I started reading on coulombs and fields and weak and strong forces, and I am trying to imagine the whole thing, say an amplifier, in terms of electric fields and forces and potentials and energy and waves, and accelerated charged particles loitering everywhere and integrals and formulas, and strong and weak interactions and dark matter and theory of everything. and i am getting recursively deeper and deeper into a black hole of the infinite knowledge and my brain is going to blow up but i can't stop. i am afraid it is like integrating over a closed loop and the end result will be zero.

[Anonymous No.1642615]

>>1642532
Genius.

[Anonymous No.1642626]

>>1642615
>Genius.

hardly! that's a ton of difficult work right there. and there's a good chance the coil will be damaged by a noob. so much simpler to simply cut off the top of the transformer with a hacksaw. also, he'd need DC to magnetize and AC to demagnetize.

>>1642557

neither circuit is any good. the second is actually funny, with the 2 reverse batteries cancelling each other out.
look for the Mimm's books in the top post. one of them will cover a simple transistor amp.

[Anonymous No.1642637]

>>1642557
>common-collector transistor
>no base-current limiting
>no common ground
>confusing current-amplification for voltage amplification
>no transistor biasing
>no filtration
>accidentally almost made a totem pole
>voltage sources in anti-series
>grounding tip instead of sleeve
As much as I'm enjoying picking apart your circuit, you won't hear anything with either of those. Have a look at amplifier topologies like the "common emitter amplifier". Then ignore them and buy an audio amplifier IC like the LM380. Or better-yet, a pre-made class-D amplifier board.
Also driving a large speaker like that off an AA battery or two isn't going to happen.

[Anonymous No.1642638]

>>1642521
>pic part number
really? All he had to say is "pic without any sort of usb interface built in" and I think that is implicit.

[Anonymous No.1642640]

>>1642336
I think I'll just buy a usb-serial adapter cable..

[Anonymous No.1642641]

>>1642638
is it an I2C or SPI EEPROM?

[Anonymous No.1642647]

Need to power and control at distance a small electronic device that needs 6V. I have no 6V supply so I got a lm2596 adjustable module like pic related to step down from my 13.8V supply. Gonna use a remote relay to power it on and off.

Want to know if a cheap module like the one I'll be using could "spike" over the adjusted voltage as soon as it turned on before soldering stuff. Also if anyone has used these things, do they get very hot? Mine's not supposed to pull over 1 watt, but it's gonna be in an enclosure with wood near it.

[Anonymous No.1642650]

>>1642641
I2C

[Anonymous No.1642651]

>>1642647
>could "spike" over the adjusted voltage
that's handled inside the chip, so if the chinks did a good job of copying the lm2596 then you should be fine.

>do they get very hot?
it depends on load. if you're drawing 1W max it won't dissipate over 1/4W which is nothing as long as you don't wrap it in insulation.

remember to put the switcher close to the device so you don't suffer from as much resistive voltage drop and coupled noise.

[Anonymous No.1642652]

>>1642647
for 1w you will be ok. They won't even get near toasty at that power.

[Anonymous No.1642665]

>>1642626
>he'd need DC to magnetize
since you aren't aware that just clicking the switch while the tool is against the coil has the ability to magnetize the tool, I'll just disregard the rest of your spiel

[Anonymous No.1642677]

How do I find out how much power a brushless motor generates at a given RPM?

[Anonymous No.1642686]

Where can I find comprehensive resources on motor driver for brushless dc motors?
This stuff is black magic to me so I want to try to make my own from scratch with a microcontroller.

[Anonymous No.1642690]

>>1642330
> doesn't microchip has a usb framework for crappy pics?
A lot of the PIC18s support USB (low speed = 1.5 Mbit/sec and full speed = 12 Mbit/sec). MPLab has code for USB-CDC (communication device class, i.e. USB-serial).

[Anonymous No.1642691]

>>1640480
Are those high voltage exposed metal?
There is no plastic insulation?

[Anonymous No.1642703]

>>1642686
find a datasheet for a bldc driver chip. texas instruments probably has some, and their datasheets are great at explaining theory.

[Anonymous No.1642706]

>>1642686
Look up brushless controller timings.
You'd have to generate precise timings for each brush so prepare to buy a ton of motors in case you burn them. Your micro should be able to read PWM as a control signal and adjust brush timings in response to increase/decrease speed.

[Anonymous No.1642758]

>>1642626
>there's a good chance the coil will be damaged by a noob
>>1642626
>so much simpler to simply cut off the top of the transformer with a hacksaw.

Genius!
No chance of damaging the coil while cutting on the transformer with a hacksaw.

[Anonymous No.1642766]

>>1642677
You mean electrical power generated from spinning it? Assuming an ideal motor EMF = Kv * RPM, maximum power point is where load impedance = motor resistance, which gives power = (EMF^2) / 4R

[Anonymous No.1642813]

>>1642691
You aren't very smart are you?
High voltage power lines aren't insulated because the insulation does nothing

[Anonymous No.1642816]

>>1642529
>>1642545
>>1642561
I simplified the circuit by getting rid of the unnecessary flip-flops. Now it works like it should.

[Anonymous No.1642817]

>>1642816
>>1642545
Schematic:

[Anonymous No.1642818]

And here's a commercial traffic signal control unit for comparison.

My dream is to build such device some day.

[Anonymous No.1642837]

>>1642818
literally a bunch of microcontrollers
>CAN
patrician choice

[Anonymous No.1642866]

>>1642816
I had to switch a real traffic light with three 230V/60W light bulbs for a waiting room. The output current of the HC4017 was enough for the opto-SSRs I used and the monitor LEDs.

[Anonymous No.1642869]

>>1642818
grab a couple of arduinos and you can do it in a day

[Anonymous No.1642887]

>>1642817
Why do you starve the transistors? Normally you drive them to B=10..20 for switching. 10K would be reasonable.

[Anonymous No.1642897]

>>1642818
>Half the reason my project looks like baked shit is that I don't know the names of connectors and cables in english or in my native tongue
>just weld everything

[Anonymous No.1642900]

>>1642818
>took about 4 big clive can bus related videos for to actually know how to write that
>canvas
>cannabis
>canwuss
>canbas
>campus

[Anonymous No.1642919]

>>1642887
That's a good point. Need to take a look if I have any 10k resistors. Thanks for your input

>>1642837
Ideally I wish to use CMOS logic to drive the sequence. Each sequencer would have a "start" input line, and a rising edge on that line would start the sequence. Maybe the microcontroller could orchestrate the intersection simply by sending start pulses into each sequencer.

[Anonymous No.1642923]

>>1642866
Thanks for sharing Anon. Looks nice. Is that light used for decoration? Or for some kind of queueing system?

[Anonymous No.1642930]

is there such thing as a dual lm386 IC like how there's the 556?
It would be extremely convenient for me when I'm making stereo amplifiers

[Anonymous No.1642946]

>>1642930
TDA2822

[Anonymous No.1642947]

when harvesting through hole components from old circuit boards, what problems could arise from me simply clipping the old leads off (From the component side of the board) and then just soldering new leads onto the old lead stubs?

I've never had much luck with desoldering components

[Anonymous No.1642948]

>>1642930
LM358, OPA2134 and TL082. Need dual supplies though unlike LM386

[Anonymous No.1642975]

>>1642947
>soldering new leads onto the old lead stubs

[Anonymous No.1642998]

>>1640236
battery pack wont charge
>Limefuel LP200X
>8 cell

i plug in charger, it says its charging but the voltage of the battery circuit doesnt change. the usb input is giving 5v.
i cant find any board specs online
what do?

[Anonymous No.1643003]

>>1642998
>voltage of the battery circuit doesnt change
what is the voltage?

[Anonymous No.1643013]

>>1643003
3

[Anonymous No.1643015]

>>1642923
>queueing system?
Yes, queueing system for actors in a tv studio.

[Anonymous No.1643031]

>>1642919
>being this obsessed with discrete logic
and this is why you're not designing real equipment

>>1642948
lurk more

[Anonymous No.1643033]

>>1642119
>You can't reason someone out of a position they didn't reason themselves into.
Do I need to "reason" myself into thinking something is terrible when I can do that by simply having to use it?

[Anonymous No.1643035]

>>1643013
>3
don't know about yours but some battery managers have a low threshold
if the battery gets below a certain voltage, they don't attempt to charge
I wouldn't think three volts was low enough to enable this but ya never know

[Anonymous No.1643039]

>>1643035
Li+ batteries are considered deeply discharged below 3V and can't take full charging current without risk of fire. modern chargers restrict current until that 3V threshold is reached

[Anonymous No.1643042]

>>1643035
>>1643039
what's the worse that cound happen if i nigger rig them to charge from 5v 0.5 amp?

[Anonymous No.1643043]

>>1643042
i forgot to mention that the charger shows 14% charged

[Anonymous No.1643044]

Could I hook up one of these boards to the two terminals of my 8 cell battery?
https://www.aliexpress.com/item/32615930404.html

[Anonymous No.1643045]

I have camera from 70's and its lightmeter is built to work with two 1.4V mercury cells. I've been using two SR44 batteries but 3.1-3.2V is too much so there is really bad exposure errors in some situations.

Would you cut voltage to 2.8-2.9 by using regulator, schottky diode or something else?
Camera uses CdS LDR and its current is really low. Haven't measured mine but cameras from same decade uses similar LDR's and some people say the current is in µA class.

[Anonymous No.1643049]

>>1643043
then believe it

>>1643042
you aren't taking Li batteries seriously enough to use them. choose a more robust, idiot-proof technology

>>1643044
see above

>>1643045
you need a low-quiescent-current regulator. those don't come in adjustable versions because the current consumption of the output voltage divider defeats the whole aim of low quiescent current. fortunately for you, Pic related is available in a 2.75V version

[Anonymous No.1643050]

>>1643043
>the charger shows 14% charged
depending on the rate of charge (500mA, 1A, 2A, etc) it could take days to recharge an eight cell pack that is fully discharged
How long have you had it in charge mode?
Just leave it overnight and see if it's improved.

[Anonymous No.1643051]

>>1643045
>built to work with two 1.4V mercury cells
If the cells are in series, use one SR44 and a 'filler' of some sort for the missing cell.

[Anonymous No.1643052]

>>1643033
You're conflating being unable (or unwilling) to understand something with it being objectively bad.

[Anonymous No.1643053]

>>1643050
i left it 12 hrs at .5 amp and no change

>>1643049
i guesss we'll see

[Anonymous No.1643054]

>>1642998
>i plug in charger,
Identify 'charger' please.

[Anonymous No.1643056]

>>1643054
it charges from the micro-usb in the far right of the pictures

[Anonymous No.1643058]

>>1643045
www.google.com/search?q=mercury+cell+replacement

[Anonymous No.1643059]

>>1643056
>it charges from the micro-usb
not the port, the charging device - the charger
>>1643053
>.5 amp
that's probably the majority of the problem
get a 1A or 2A charger for it.
If those are 2Ah cells, you're looking at ~32 hours at 1/2A
>>1643044
>one of these boards
that's what the enlarged part of pic related is
except it's for your particular setup

[Anonymous No.1643061]

>>1643059
oooh interesting. I'll dig up my 2 amp cell phone charger. maybe i can swap out parts if it still doesnt charge.

[Anonymous No.1643093]

>>1641603
>>1641690
>>1641707

Then say 1000uF or 1mF
1k uF is dumb, we have a functioning metric system for a reason.

[Anonymous No.1643098]

>>1641854
>>1641857
How about you give us a little more info what what you are doing in your project? At first you were saying a desk fan is restarting your 'duino, and now you're talking about a relay.
Are you controlling your fan with a relay run by the 'duino?

[Anonymous No.1643119]

>>1643093

mF is deprecated.

Because reasons.

[Anonymous No.1643124]

>>1643119
boomers ruined it for us by using mfd for microfarad

[Anonymous No.1643129]

>>1643058
zinc/air, so simple. no silly electronics that permanently drains

[Anonymous No.1643135]

Sorry if this sounds noob, but I have a power supply with 3 24v+ and 3 24v- outputs. I have 2 12v strip lights and I want to connect both to the 24v outputs. How do I safely do this?

[Anonymous No.1643139]

>>1643135
you don't
you add a step down converter from ali for about a buck, set it for 12V output, and put the strips on the output side of that. or, you get a proper 12V supply

[Anonymous No.1643140]

>>1643139
I found a switch to toggle to 12v mode.
how many 12v lights can I connect to 1 of the outputs?

[Anonymous No.1643142]

>>1643093
>1kμF is dumb

No more dumb than μμF, which was the accepted convention for a long time until picos were discovered.

[Anonymous No.1643161]

Hey y'all, got a question regarding multi-amp setups. Tl;dr is at what point do I need a line-level distribution amp?

In more detail, over the past decade I've collected a bunch of amps and speakers. I just bought a house where I can finally get loud (fuck apartments), and I wanna go full retard and put them all together in the basement as a wall of speakers. I know, it's dumb, but I have nothing else to do with them, and the gimmick makes the 12 year old in me smile.

The only issue I see is getting the line level source (probably a computer) into all the amps. I think I have around half a dozen, and I don't know if just splitting the signal that much will work. Of course there's the attenuation to deal with, but would there be any other weird shit that happens with that many splits? Destroying the highs? (as if I were expecting real quality out of this rig, lol) Destroying the amps? And as a side question, how would that attenuation behave? A simple division between the amps, or will it be more messy due to differing input impedances or something?

I have a few mixers that I could use the various main outs, monitor outs, etc. on, but I'd like to keep it simpler, and I think they only total 3 stereo outs anyway.

I'm willing to buy a line level distro amp, something like the Behringer Powerplay HA6000. I'll probably get one eventually cause individual control of the systems also makes the kid in me excited, but until then, I'd like to know if I'll blow anything up by splitting the line signal to 6-8 amps.

Any info is appreciated, thanks in advance my dudes

[Anonymous No.1643186]

>>1643161
Update, I'm definitely getting an ART HeadAmp6Pro 6-channel Headphone Amplifier. I'd order it right now if I didn't just buy a house.

Another thought I just had was using the headphone line outs on the amps, and daisy-chaining them that way. I imagine it'd create a cascading effect from the volume levels of the individual amps, where it would become finicky and dumb after 2 or 3 amps in the chain.
I think most of the amps don't have pre-volume line outs. Heck, are most line outs on amps, particularity guitar amps, just "dumb-splitting" the signal coming in? Or do they add some electronics in the chain?

[Anonymous No.1643189]

>>1643161
ideally, every few meters

>>1643186
>plugging headphone outs into line ins
go back to >>>/g/

[Anonymous No.1643198]

>>1642758
>No chance of damaging the coil while cutting on the transformer with a hacksaw.

since you can use the plastic form as a guide to your blade, a blind person could cut open a transformer.

>>1642665
> just clicking the switch while the tool is against the coil has the ability to magnetize the tool

if using 60Hz AC you'd need to flick your switch on/off in less than 8 millisecs, and time it exactly with the positive or negative voltage peak. that seems impossible given a typical switch bounces for 20ms.
OTOH, with DC, you can do it leisurely and stroke it back and forth the way your mom showed you.

[Anonymous No.1643199]

>>1643189
pls help, why can I not plug headphone outs into line ins

[Anonymous No.1643200]

>>1643161
>>1643186
If you are going with more than 2 amps, I'd say to go ahead and grab a simple distro amp. Six would certainly be too many.

[Anonymous No.1643205]

>>1643200
That's what I was figuring. Any knowledge on why, exactly? What would get shitty in splitting it that many times?

[Anonymous No.1643210]

>>1643198
Not all transformers have those plastic guides, but I agree that you can cut one open without damaging the windings. Usually they're only welded on the outside, so you only need to hacksaw 2-5mm into the side, which will be 10-30mm away from the windings themselves. But trying to remove a set of windings without scratching it on the transformer body might prove difficult.
Pretty sure you're right about the DC being required to magnetise.

[Anonymous No.1643370]

>>1643098
yes, the fan is connected to a relay that is controlled via arduino, but sometimes i get a reboot even if the relay has nothing connected to it, but in 100% of the cases the problem only happens when the relay switches. as long as i don't switch the relay, the sketch can run for months without any problems
With the fan connected the reboot happens much more often (sometimes several reboots in a row), but that will be taken care of by the snubber
but there must be something else going on since it sometimes reboots also with just the empty relay, now i looked at the relay board and chinks use a diode to handle the induction built up when switching, but maybe it is not enough
Whatever is causing the problem is very likely amplified by the fact that the relay is literally sitting on top of the IC, but due to space constrains there is nothing i can do about that
Some anon suggested adding a small cap in paralel with the diode, so i will be trying that as well to see if it does anything

[Anonymous No.1643379]

>>1641131
>>1642261
I'm still waiting.

[Anonymous No.1643382]

>>1643379
your choice

[Anonymous No.1643387]

>>1643382
reeeeeee
post it

[Anonymous No.1643401]

If you have a 2ah battery and a device that uses 2ua (sleeping ic), does that mean that i can power it from that battery for over 100 years? Am i calculating that correctly? seem too much

[Anonymous No.1643405]

>>1643401
no. batteries have a self-discharge rate represented as a percentage of charge per month, which also limits their lifespan.

[Anonymous No.1643408]

Do these gauges have a name other than analog voltmeter? I like the aesthetic

[Anonymous No.1643409]

>>1643408
my local shop calls them "panel meter"

[Anonymous No.1643414]

>>1643405
thats gay
this is 2020 why the fuck don't we yet have scifi batteries that last thousands of years and can hold massive charges?
fucking christcucks and their dark ages, this is all their fault

[Anonymous No.1643415]

>>1643414
batteries are one of the biggest things holding us back from the #future. energy storage is a bitch.

[Anonymous No.1643421]

>>1643414
If you can get your hands one of those portable fission reactors, it will last quite a while

[Anonymous No.1643422]

>>1643408
That's a moving coil meter, tolerance 2.5% when mounted vertically like a panel meter. The native sensitivity of the meter movement is often 50µA or so. If you want to measure voltage you add a series resistor.

[Anonymous No.1643527]

Will this work? Assume I don't want to replace the relay with a mosfet + circuitry to generate a brief pulse.

[Anonymous No.1643574]

>>1643527
Don't see a capacitor bank. Where is it?

[Anonymous No.1643601]

>>1643527
do your own design review. build the thing and report back, you know, like a practical hobby

[Anonymous No.1643631]

>>1643527
should work, though your hysteresis seems pretty huge. is all of that shit just to turn on a LED? not a welder but you shouldn't really have to cut off your charge supply when welding because the 100 ohm resistor will current limit it. also your storage is tiny. i don't think it could burn my tongue.

[Anonymous No.1643731]

>tfw someone gets ripped out of the thread by the roots and puts /ohm/ back under bump limit

[Anonymous No.1643736]

>>1643370
Thanks for the info. Does it reboot when switching the relay ON, OFF, or both?

You're getting voltage spikes from the relay coil for sure, it has nothing to do with the fan connected to it. Without schematics for the relay board, I'm only guessing here. There should be a diode across the collector and emitter on the transistor to drive the relay, and that protects the transistor from voltage spikes when switching. It sounds like those spikes are making its way back to the 'duino board.
Try using a basic diode from the arduino to the relay board, that might help. If that doesn't help, try putting one between the arduino and VCC. VCC may not be protected on the relay board and the spikes could be going that route.

Again, without schematics, I'm just guessing here.

[Anonymous No.1643826]

>>1643198
Speaking of transformers, how do you wind your own switched-mode power supply transformer? Beyond the obvious
>hurr wind some wires
Shit like gauge size, number of windings, parallel windings, and how they relate to desired frequency, voltage, and current

[Anonymous No.1643842]

>>1642261
>>requesting V=IR Homer
>anyone?

is this what you wanted?

[Anonymous No.1643847]

>>1643826
depends on the topology, among other things. if you're lucky, your switching controller chip maker has software to do that for you, which will dispense complete pleb-ready directions and bills of materials for your new transformer. if not, check their literature for app notes on switching power supply transformer design. failing that, find your trusty scientific calculator and into the fray https://en.wikibooks.org/wiki/Electronics/Transformer_Design

[Anonymous No.1643905]

>>1643842
yes, thanks anon!

[Anonymous No.1643945]

100% brand new straight from the factory guarantee

spot the problem here

[Anonymous No.1643947]

>>1643945
If a deal on Alibay sounds to good to be true it probably is.

[Anonymous No.1644010]

>>1643408
It's a galvanometer anon.

[Anonymous No.1644011]

>>1643945
Whoo, you are lucky!
The factory even send it and customize it for you!
Great quality stuff.

[Anonymous No.1644012]

>>1643574
Falstad doesn't simulate capacitor banks, but here it is. I have 6 of them.

[Anonymous No.1644032]

>>1644012
Just call your cap 27mF.
12V 27mF 2Ws
Not enough to weld much of anything.

[Anonymous No.1644055]

>>1644032
That's 9F, not 27mF

[Anonymous No.1644103]

>>1644055
6*3*1500µF=27mF, no?

[Anonymous No.1644109]

>>1644103
Sheeyt, you're right. I forgot the "u" was for micro, not mili.

[Anonymous No.1644117]

>>1644103
for capacitors, µF=mF
1500µF is the same as 1500mF

[Anonymous No.1644130]

>>1644117
no

[Anonymous No.1644154]

>>1644109
>I forgot the "u" was for micro, not mili.
seriously
what did you thought m stands for?

[Anonymous No.1644274]

So... I bought a power supply on Amazon (15v, 2A) and the fucking thing died after i used it's usb charging output to charge my phone. The screen showed the full 2 amps being pulled by the phone as it was charging. It actually charged the phone extremely fast. The next day, i went to power the thing up to work on a project, and the thing was totally dead. I contacted the seller on Amazon (yaogong) and they asked me to take a picture of the inside. The transformer was melted and somewhat burnt. They told me they were sending me another unit, after warning me that the device's primary use is to do cell phone repair... I didn't want to argue and tell them it WAS a cell phone that was plugged in and i wasn't trying to power my fucking refrigerator with it (the tracking number is from China, so who knows when I'll get it.... Maybe next year.) I want to replace the transformer with a better one, but i cannot find anything on the net. Maybe my Google-fu skills are rusty. Any suggestions? Maybe upgrades? Also, the fucking thing slightly shocked me when i accidentally touched the transistor in the back (2n3055)

[Anonymous No.1644300]

>>1643945
>100% brand new straight from the guy at a bench with nail polish and a rubber stamp
>in an assortment of styles to suit your every engineering mood
my general rule is: if the ali price is less than the LCSC price per each in lots of 2000-5000, keep one hand on your wallet

>>1644117
that hasn't been true for decades, boomer

>>1644274
scale isn't exactly clear, but at first glance that doesn't look like a 30VA mains transformer to me

[Anonymous No.1644303]

>>1644300
>that hasn't been true for decades, boomer

https://www.westfloridacomponents.com/NP028APL06/100uF+100mF+50V+Axial+Non+Polar+Electrolytic+Capacitor.html

[Anonymous No.1644305]

>>1644274

most of the info you need is there on the top.
input = 120Vac (red wires)
output 1 = 24Vac (blue wires)
output 2 = 10Vac (yellow wires)

as for current ratings, the size would suggest about 2-3 amps for either output. (you can always choose higher, but never lower)

you can tell they used the cheapest transformer possible. it should have included a thermal fuse that would have spared the melting of the core, and burning of the wires.

[Anonymous No.1644317]

>>1644303
>manufacturer: we made it ourselves

[Anonymous No.1644323]

>>1644274
>I bought a power supply on Amazon
Does it look like pic related?

I searched for the transformer number 1501T and found this.
http://www.amazon.com/1501T-Supply-Adjustable-Mobile-Repair/dp/B074RDZSMV

[Anonymous No.1644328]

>>1644305

I'm getting all kinds of useless shit for results on searches with the voltages as search terms. Is there any specific words i should be using? I don't know what those are called. Dual output? And more importantly, is there anything i should be looking for to prevent that from happening? I'm down for installing a thermal fuse. Anything like that? Thanks for the help, dudes.

[Anonymous No.1644331]

>>1644323
Kind of... I'm attaching a pic. Mine is the 1502D+

[Anonymous No.1644340]

>>1644154
Why the hell do they sneak in a greek letter just because?

[Anonymous No.1644348]

>>1644340
>the famously nationalistic French sneaking in a Greek letter
odd, isn't it? anyway m is ambiguous, as you see here. u has been a perfectly acceptable alternative multiplier for quite some time

[Anonymous No.1644353]

>>1644348
If the typewriter has no µ.

[Anonymous No.1644357]

>>1644328
>getting all kinds of useless shit for results on searches with the voltages as search terms

google is not gonna be much help. the correct way to do this is to go to a retailer or manufacturer's websites, and use a parametric search (you choose the parameters from a list) on ''power transformers''.
e.g. Digikey finds something kinda similar: 10 and 20V dual secondaries, 40VA. part number hammond HM4965-ND.

a better approach would be to choose 2 diff xformers, one for 10V and another for 24V after measuring the actual currents from a non-dead unit.

it goes without saying that an expensive transformer from a name brand like Hammond is gonna be well made and well protected. it's not gonna melt.

[Anonymous No.1644373]

>>1644357
$40 transformer
to repair
$20 device
https://www.alibaba.com/showroom/1502d-power-supply.html

[Anonymous No.1644393]

>>1644373

quite a conundrum. do i spend $40 on a xformer and get a working unit, or do i buy two $20 power supplies and risk ending up with two non-working units after a week?

[Anonymous No.1644400]

>>1644393
if you're just trying to power stuff, buy a semi-enclosed PSU for "LEDs" and a bag of step-down converters

[Anonymous No.1644422]

>>1644400
I already have that. I've been powering all my stuff with generic wall warts and Stepdown converters for a couple of years. I just wanted something a little fancier/less ghetto.

[Anonymous No.1644437]

>>1644117
Usually that's written as mkF, with the "mk" being "micro". I think it's somewhat common with old soviet caps.

[Anonymous No.1644504]

>>1644422
https://www.aliexpress.com/item/32901796586.html?spm=2114.search0104.3.1.190a2563bJJ2bo&ws_ab_test=searchweb0_0%2Csearchweb201602_3_10065_10068_10130_10547_319_10546_10059_10884_317_10548_10887_10696_321_322_10084_453_454_10083_10103_10618_10307_537_536%2Csearchweb201603_60%2CppcSwitch_0&algo_expid=c0c2c17b-ebb5-44e2-aa70-8fcbdf3821e0-0&algo_pvid=c0c2c17b-ebb5-44e2-aa70-8fcbdf3821e0&transAbTest=ae803_5

[Anonymous No.1644582]

how can i get started programming micros with a usbasp and some atmegas/attinys?
at this point the arduino environment is more hassle than its worth when it comes to bloating up my low-memory attiny13s.

[Anonymous No.1644583]

>>1644582
Have you tried the official IDE, Atmel Studio?

[Anonymous No.1644587]

>>1644130
>>1644437
>>1644303

[Anonymous No.1644628]

>>1644504
Yeah.... no.

[Anonymous No.1644697]

>>1644582
use atmel studio like >>1644583 mentioned
As for usbasp - install avrdude for use with usbasp to flash hex, fuses (at least what I used in the past)

Alternatively, you can try using winavr but it's outdated and abandoned as far as I remember

Since Atmel is now owned by Microchip it's possible their MPLab might support AVRs as well

[Anonymous No.1644816]

>>1644628
>Yeah.... no.
Why? It's a decent power supply

[Anonymous No.1644883]

>>1644504
monetised post?

[Anonymous No.1644956]

>>1644583
>>1644697
>winshit only
no I have not

[Anonymous No.1644971]

>>1644956
avr-gcc and avr-binutils are almost certainly available from your linux distro. make a simple Makefile with http://alfred.sax.de/~joerg/mfile/ , then compile. see the avr-libc user manual http://www.nongnu.org/avr-libc/ for helpful things like busy-wait macros and hardware register names aliased as global vars. burn with USBasp controlled by avrdude
>inb4 b-but I'm using a mac
get brew and leave us alone

[Anonymous No.1644977]

>>1644971
Looks pretty handy thanks, I'll give it a shot.

[Anonymous No.1645073]

>>1644883
No. The link is just fucking long
If you search rigol power supply and then click the same model, it will give you the same link

[Anonymous No.1645085]

>>1644816
It's... TOO decent.

[Anonymous No.1645088]

>>1645085
and did that ever stop the FUG power supply anon?

[Anonymous No.1645095]

>>1645085
https://www.ebay.com/itm/Rohde-Schwarz-CS-PSSU-Power-Supply-w-Power-Cable-Free-Shipping/332918042373

[Anonymous No.1645115]

>>1644956
Mplab X runs on Linux

[Anonymous No.1645117]

>>1645073
>link is just fucking long
No, it isn't. The link is:
https://www.aliexpress.com/item/32901796586.html
Anything after the ? are your private data.

[Anonymous No.1645216]

>>1640236
Ha
>be me, 10 years old
>love playing with electric fence around front yard to keep cows out
>one day decide to see if i could measure the voltage, even though I knew it was an impulse and might not work
>one lead to ground, one to the fence wire
>SNAP
>noise and smoke come from multi-meter
>it dead
>get my dad to buy a new one, wasn't scared to get hit because he told me this was a good idea
>find out the voltage is around 1,000 volts on that type of fence

[Anonymous No.1645933]

>>1642887
When I was a kid some other kid won the regional science fair with a "starved circuit amplifier." I didn't know what that meant. Maybe this was it?

The mic on his amp was so sensitive it could pic up a fly crawling across it.

[Anonymous No.1645943]

>>1645933
I doubt it, by starved he just meant it was operating in the linear region, which you'd do for an amplifier anyhow. A cursory search implies that it has something to do with tube amplifiers.

[Anonymous No.1646108]

>>1645933
It was explained in the post: lack of 'food' (base current) for switching action.

[Anonymous No.1646534]

hello, noob in electronics here. just got my 5v 10a dc power supply(pic related). when I test the + and - output with a multimeter the buzzer starts beeping. is it suppose to be like this or is it internal damage?

[Anonymous No.1646541]

>>1646534
no, it just means you're pregnant
hook L and N up to mains and turn it on. do you measure 5V at output? yes? then it's doing what it says on the tin. no? then measure ac volts at L and N. is it mains voltage? yes? it's broken. no? most likely your line cord's broken OR your power supply just tripped a circuit breaker

[Anonymous No.1646546]

>>1646541
yep it reads 5v at the output. so it's fine I guess.

[Anonymous No.1646550]

>>1646546
But what's that smell?

[Anonymous No.1646552]

>>1646546
oh, probably not pregnant then, just something vaguely like Pic related

[Anonymous No.1646553]

>>1646552
ummm, what do you mean by pregnant? I don't have an electronic basic so that's a new term for me.haha

[Anonymous No.1646555]

>>1646553
it's a dad joke, after a few beers
>a bunch of random observations about body, work, funny sounds the car makes
>am I pregnant?