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Thread started to smell:>>2677019

>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.

>Incredibly comprehensive list of electronics resources:
Additional resources below:

>Project ideas:

>Don't ask, roll:

>Archive of Popular Electronics magazines (1954-2003):
>Microchip Tips and Tricks PDF:
>Li+/LiPo batteries required reading:


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

>Recommended Design/verification tools:
KiCAD 6+
Logisim Evolution

>Recommended Components/equipment:
eBay/AliExpress sellers, for component assortments/sample kits (caveat emptor)
Local independent electronics distributors

>More related YouTube channels:

>microcontroller specific problems?
>I have junk, what do?
Shitcan it
>consumer product support or PC building?
>household/premises wiring?
More rules-driven than engineering, try /qtddtot/ or sparky general first
>antigravity and/or overunity?
Go away
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Hello electronics anons. I want to build pic/link related because it's too expensive. Any tips? Specific resources I should look at? Or do you know of a Chinese version of this product?

Looking for something that can pulse up to ~a dozen or two Hz @ 10kV x 1mA (load will range from around 3kV - 10kV x 1mA)

on the off chance this isn't for a taser, what do you want it for? what kind of output waveform are you looking for?
This one is listed as 400kV but it's closer to 10kV:
I need some help. I want to control my old bang & olufsen tv but i dont want to spend fortunes on a remote. Was looking into IR emitters until i found out b&o uses 455kHz for their remotes instead of using industry wide standard 32-38kHz. Anyone have any ideas or advice before I start this project?
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I'm working through this book, about halfway through. It has you mechanically build out breadboard circuits that the author provides.
Am I wasting my time actually putting these things together? The only way I can imagine this part being beneficial is simply to improve your motor skills and troubleshooting skills if you fuck up.
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according to some random internet dude, the Harmony H655 can be programmed to work with B&O teevees.
i have a dozen diff thrift-store Harmonys but not the 655.
if you gimme the model # of the tv i can see if Harmony has the codes available for download for other Harmony models.
>It has you mechanically build out breadboard circuits

us tinkerers never do it that way.
we just ask the Star-Trek replicator to do it for us.
It's the way to learn. Eventually you have ideas for your own circuits and then you begin by quickly breadboarding them.
Learning by practice is the best. It's obvious, right?
What is really the problem?
note this is for the PCB itself, I don't mean schematic sheets
I'm designing the board for a complex circuit in KiCad. But, the circuit is pretty much the same subcircuit copy/pasted over and over. Is there some way to only lay it out once, and then copy/paste it instead of having to laboriously re-do every single component for every single instance of the subcircuit?
Yes, there should be replicate layout plugin that allows you to duplicate layout of hierarchical sheets.
You're right, just need to slog through it. I'm sure the book will get me towards a decent level.
Also it's cool as fuck. Feels like playing with Legos again.
My ultimate goal is simply to design a coffee maker PCB.
godspeed to you anon, it's the beovision avant 28, but they all use the same beo4 remote. Pretty sure the type is 8111 but i can't get to the crt right now.
doesn't that book recommend putting BJTs in common-collector mode?
>Le taser
If I wanted to make a taser there are plenty of anarchist cookbook style guides around that give way higher power outputs. No, I'm looking for something consumer electronics grade with relatively high fidelity and bandwith. You should have a closer look at those Xp Power units - they're much snazzier than a basic arc generator. My output waveform will be quite variable, but needs to be predictable based on the input signal. This is a complex circuit riddled with technical challenges, hence why I'm asking my question
Ok with a lot of work, this basic layout might be a jumping off point for what I actually want
>Input current 2-5A
Would it work if I run it at under an amp?
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Apparently 2.6 X 3 = 10
According to chinks...
Also bastards have installed awful BMS that didn't balance shit, and now there is a big difference between cells (3.8 to 4.22V)
I've installed good BMS with balancing, but the question is, will balance fuck up this big, or i'm better off charging each cell individually?
And BMS is painfully slow at balancing too
I just measured like 650mA@3V (2 AA batteries).
880mA on second test with spark gap 0.5mm further apart
decided to charge each cell with a glidefish™ charger. I'm starting to suspect some cells are dead. Fuck me.
I think you have one or more bad connections either in the wiring or spot welds.
How come secondarys on microwave transformers will kill you, shouldnt the 1ghz frequency create skin effect like a tesla coil? what about a 25khz 10kva 30ma secondary
Spots look fine. Idk about balancing leads.
I blame manufacturer, they've installed a shitty BMS with no balancing, and since cells aren't LG/Panasonic/Sanyo, you need balancing as chink cells are all over the place when it comes to capacity, ESR and self-discharge.
Nerves can't process high frequency, so you're just being fried slowly to perfection.
Skin effect doesn't affect stuff that barely conducts electricity.
If you touched both sides of a high frequency high voltage secondary you be conducting that current though, would the current still pass through your organs or just skin tissue
>How come secondarys on microwave transformers will kill you
The transformer runs at 50/60Hz and steps up the voltage to ~2.2kV at about 1A continuous. That's 2200W AC.
>what about a 25khz 10kva 30ma secondary
I don't think you would feel 25kHz, but that's still 300W output and could burn tiny holes in your epidermis.
Exactly, this is what I meant.
can we get this kid an /ohm/ sponsorship so he can make bigger arcs in his room with more powerful equipment?
>shouldnt the 1ghz frequency create skin effect

the GHz signal is what comes out of the klystron, not the transformer.
Don’t buy or read anything using the term “maker” or its derivatives. It’s the hallmark of bullshit.
> coffee maker pcb
??? My coffee maker has made perfect coffee for 25 years, and I can guarantee you there is no PCB in there.
> ohm sponsorship
He’s already on track to win a darwin scholarship.
You chaps got any tube amp kits/resources?
Cursory search produced fully populated boards and premade enclosures where the hardest part is finding the right allen key to screw it all together. Don't mind if the pcb has all the surface-mounted shit baked on already, but something simple would be fine too.
>Looking for one of my analog module bookmarks ended up in a tangent looking at little tiny displays
>Didn't even find the bookmark I was looking for
Welp. blew up the charger.Fuck.
Lii500 engineer. RIP, it cant handle 24V instead of 4.2V
Thanks, I'll look into it then
A ZVS transformer driver followed by a rectifier is going to be the simplest and cheapest thing like it, though the output regulation is minimal. What kind of voltage regulation do you need? What are you powering with it?

>kinda amateurish demeanour (could be forgivable if the production quality was there)
>not sufficiently edited to trim out the fluff
>kinda not sufficiently researched or scripted beforehand
>vertical camera
>shitty camera
>shaky camera
>background noise
>kinda shitty mic
>poor working environment
Consider doing what bigclive does, having a phone/tablet as the camera mounted above a benchtop. An external microphone would be a benefit. There are things you could add in post, like a screenshot of the webpage you bought the neon sign transformer from, or the continuous display from a power meter, be it from a different camera or just a zoomed section of the current camera. A quick description of the MOT-based supply would also be nice.
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What’s the best way to charge NiCd with the power supply? The ol’ Google is giving me varying answers. This pack probably hasn’t been charged in years fwiw.
Tilers tile; plumbers plumb; welders weld.
Electronics hobbyists mechanically build out breadboard circuits that the author provides, and then some.
>What’s the best way to charge NiCd with the power supply?

The best way is to not. End-of-charge state for NiCd/NiMH cells is determined by a slight dip in voltage. A simple CC/CV power supply has no way of detecting this, and will very quickly trash the cells.

The graph showed a big temp increase too above like 80%, maybe I can wait til it’s nice and toasty.
Float it up to capacity at 1/40C over two days.
>This pack probably hasn’t been charged in years fwiw
It'll need a few full cycles to recondition; Expect it to underperform for the first two or three, and also to have lost a little headroom over the years.
>>2683909 Is somewhat correct, but has apparently never heard of a timer plug. Gay indeed. Overcharge damage is a product of charge rate and time. Keep the charge current below 1/20 capacity and the period > day, and you'll be fine.
What graph? Don't cook your cells.
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I wonder what kind of temp sensors the Ridgid NiCd batteries had in em, maybe I can trick this charger into doing the Ryobi battery.
>What graph?

It’s an old NiCd Ryobi pack that was bound for the trash so idc if I wreck it in the process. I’d rather not destroy a charger though.
>ZVS transformer followed by a rectifier
The thing is going to be hooked up to a 1-2k mAh battery. Surely I don't have to screw around with DC->AC->DC? The off-the-shelf one uses a DC oscillator into a transformer
>What kind of voltage regulation do you need?
I don't need the voltage to be terribly stable. Pretty much the most rudimentary solution will do.
>What are you powering with it?
A soft actuator. I have electrodes sandwiched around a liquid dielectric enclosed in a non-extensible membrane. The high voltage induces a Maxwell stress which compresses the fluid when the electrodes are drawn together.
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>Surely I don't have to screw around with DC->AC->DC
There's literally no other practical method of conversion, unless you count rotary converters.
>The off-the-shelf one uses a DC oscillator into a transformer
Oscillating DC is called AC. In this case, the datasheet calls it "a qμasi-sinewave oscillator", not sure what the µ is doing there. That quasi-sinewave is very similar to the sine wave coming out of the wall (i.e. it's AC), the only difference being there are gaps between the pulses. That's how it will be regulating the output voltage; the converter performs pulse-density-modulation in response to the feedback voltage. The quasi-sinewave is fed through a transformer to multiply the amplitude (transformers only work on AC), after which it's rectified and filtered with diodes and capacitors. This kind of sine-like oscillator (quasi-resonant is the correct term) lacks the sharp edges of a traditional switching converter (e.g. flyback) and as a result it's a lot less electrically noisy.

A simple ZVS circuit is very similar, just it doesn't have the quasi-part for regulation. Generally the output voltage is like k*N*Vin, where N is the turns ratio and k is some constant. I think, it might drop somewhat under load. Find a transformer with the right turns ratio N, or wind your own. ZVS circuits do need a centre-tap on their primary. 20kV silicon-stack diodes aren't that uncommon, I bough a dozen from aliexpress for like $5. Similar story for the caps.

You may also be able to find a dedicated IC that performs a ZVS, ZCS, or otherwise quasi-resonant conversion method. Otherwise there's nothing stopping you from making a forward converter using a TL494 or similar, which actually will have feedback. But both options will be more complicated (albeit easier to adjust) than the ZVS circuit.
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I'm making a timed light that goes PIR input on timer pot-adjustable PWM MOS-driven LED.
Is there a reason not to use an op-amp configured as an astable multivibrator (pic rel) for my gate PWM signal instead of a 555?
The op-amp seems like a better option. Since there are two op-amps in a DIP-8 LM358, the second can be configured with some >megaohm resistors and an electrolytic cap as an (albeit imprecise) monostable vibrator for the timing function.
> reason not to use op-amp osc?
No good reason.
Lots of early computers used random oscillators made from leftovers or single transistors, or a couple of extra NAND gates.
Watch your current draw though, if it’s battery powered.
If you use a 555 you’d probably want the CMOS version.
>Is there a reason not to use an op-amp

the 555 has a reset pin, so you can turn the PWM on/off from the PIR without any additional circuitry.
also, op-amps are always fiddly, whereas the 555 is infinitely reliable.
even more reliable than mom.

...and the 555 can do 300mA vs 10mA for the op-amp.
Use a comparator instead of an op-amp, they're actually designed to be used with positive feedback so the output slew rate and voltage range is better. Generally higher current sinking too, though you often need a pullup.

If you do use a 555 timer, the normal NE555's quiescent current and output voltage range is pretty shit sitting 1.5V or more below the positive rail. That said, if you go for a CMOS 555, its output current sinking is a fair bit worse, and the output still sits half a volt or more below the positive rail. No clue how they got such a shitty part with CMOS.
>you can turn the PWM on/off from the PIR without any additional circuitry
The module's output has a set 8 second pull-up period, but I'd like a minute or more. Changing the module would require some very fine SMD reworking that is beyond both my dexterity and equipment.
>Use a comparator instead of an op-amp
The 358 is cheap and readily-available from a retailer down the road. It's a bit of an 'every problem looks like a nail' type of thing. Thanks for the rundown on comparators still.
>CMOS 555
>the output still sits half a volt or more below the positive rail
That's weird. I've heard their switching speed knocks the socks off the BJT variants though.
>If you do use a 555 timer, the normal NE555's quiescent current and output voltage range is pretty shit sitting 1.5V or more below the positive rail
Shouldn't be
>...and the 555 can do 300mA vs 10mA for the op-amp.
The MOS gate is only half a nanofarad. If my oscillator can switch its 10nF feedback cap at a kilohertz, then I think it'll toggle the measly gate capacitance just fine.
Help desk question – today an LED bulb in a regular 120v ceiling socket started flickering and then shut off. I almost wasn’t sure it happened/that the light had been on (dim bulb and around noon) so I reflexively jiggled the light switch, bulb came back on and did the same thing again a few minutes later. What’s causing this? Am I going to burn the place down if I keep using this? Is it the bulb/driver or the building wiring?
It's the board that drives the LED.
Swap it with another bulb to see if it's the socket or the bulb. Probably the bulb, but sometimes the contacts of a bulb get bent, and with the thermal expansion from running the bulb for a few minutes they can go open-circuit. Of course, heating up can also cause the LED bulb's board to trigger an overtemp condition and limit power, maybe the thermal paste has just gone shit.

Thanks, I figured but wanted to make sure it was safe (unless I’m misunderstanding what’s going on with open circuit)
>has a set 8 second pull-up period, but I'd like a minute or more.

no need to modify the PIR, just use a couple of schmitt gates to stretch the pulse.
a 555 monostable can do the same job.
even an op-amp can do it, if you have a hard-on for analog.
> more chips
The guy has the extra op-amp, any designer would just be efficient and use it.

> zoomer inb4
Just use an arduino and import some timer libraries
>How come secondarys on microwave transformers will kill you, shouldnt the 1ghz frequency create skin effect like a tesla coil?
2 reasons. First of all, they don't operate at 1 ghz, you might be confusing the transformer with the magnetron. Second, since the secondary is isolated from the primary, if you accidentally short the secondary through your body, a cfgi outlet won't protect you since there is no loss of current in the primary live and neutral wires. This means if you get zapped, you're cooked until the circuit breaker pops, which might or might not. At such high level powers, what kills you is not really the electricity stopping your heart anymore but the electricity cooking your body. Think of it similar to the electric chair and how some people would be cooked alive in it.
Whose dick do I have to suck to stop these 'convergence failed' errors?
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Oh, I just realised that putting a hall sensor between the permanent magnets of a brushed DC motor's stator won't give a good speed signal; the rotor will always be putting out the same magnetic field polarity at that position, the magnetic field does not effectively rotate. It looks like there probably are some locations within the motor that I can get a solid speed reading from (since it's not sinusoidally driven), but I wouldn't easily be able to fix the hall sensor there like I can between the magnets. Also it gets switching noise. Guess I'll JB weld a pair of small magnets on the outside and hold a hall sensor to that. Optical is probably too much of a pain to get working without good baffles, which would be bulkier.
>testing motor
>now have speed measurement sorted
>still don't have current measurement
>assume current won't spike so long as i increase the duty-cycle steadily and have no mechanical load
>write code to steadily increase speed, and to cut the power if the hall sensor stops picking up a signal
>get up to 5100RPM
>kinda shaky but feels fine
>shut it down by pulling hall sensor out of the way
>motor brakes suddenly using the low-side MOSFET as a freewheel diode
>sudden torque spike
>10A psu just stops outputting any voltage
oh shit

it started again at least, but i should add a soft-stop as well as this soft-start.
The body diode is a mfg artifact, not a “free diode”
It’s also not a schottky diode, which is probably what you want as a flyback.
Start-up diagnostics should test to ensure the flyback diode is still working. It can be incorportated into the slow-start/stop.
>It’s also not a schottky diode, which is probably what you want as a flyback
Synchronous diodes are even better.
The brushed motor is in parallel with the low-side FET of a half-bridge. The half-bridge is either pulling low or high, one FET is always on. So during the "off-time" of the PWM, and when I tell it to shut off, current is cycling through the motor with the bottom FET acting like a synchronous freewheeling diode. Basically I'm shorting the motor out.
Even if it was a normal freewheel diode, it would barely give more effective electrical resistance than the FET, both would cause the motor to stop pretty quickly.

Also I don't call it a flyback diode, because flyback converters don't use a diode in parallel with any magnetic element. Such a diode would prevent the boost converter style voltage spike. It's a misnomer. I would suggest you do the same.
> freeloading diode
I make all my schematics using electron flow instead of conventional current flow because electrons are negative, not “positive” … it’s a misnomer. I suggest you do the same.
Yahoo, it's reliably working up to 18353RPM at maximum duty-cycle, which is right about this motor's purported maximum speed. I get the feeling this spin-coater is going to kill me. But now I really do need to implement some sort of current measurement, along with a manual control scheme. The ADC isn't working properly at the moment, definitely a brain problem since it works when I use the tarduino command but not when I access the register directly.
He explains the difference between the 2 but doesn't offer a blanket recommendation.
Probably true. Surprisingly this book was decent but it's a only starting point. I'm on AoE now and it's 10x higher level. Difficult as a beginner but the value on each page is huge.
Can a two-input latch be configured into an astable multivibrator?
yes, no, maybe, i don't know
rather than blindly making junk circuits, why not make something you can actually use? guitar effects, synthesizer modules, test equipment jigs give tons of opportunities to make useful shit, even at a beginner level
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how hard is it to actually solder a 2x2mm chip to a circuit board using a solder paste without a stencil in a home oven?
If it were that easy then all the girls would be doing it.
pretty easy. wick away the factory balls.
make leaded or low melt new balls using iron.
stick to pcb with flux put in oven.
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Electronics bros, need a multimeter for my nephew (18yo). Level is higher than high school but lower than university.
Is pic relevant still relevant?
What are the current value kings?
>Budget is $50.
>Will mostly be used at low voltages (<=24)
>should be able to handle measuring AC mains (~240V) for a few seconds w/o frying
So far I know about:
>aneng q10
>aneng 8008
>aneng 8009
Which is best? How'd you sort them? Any other options to consider?
I got a an870 but I kinda wish I paid 2x more for a LCD display and a oscilloscope.
the specs on the scope about what you expect for a $40 DSO (and the specs are worse!), but the I am jealous of the display, and 18650.
Technically, because you are measuring mains, you should just get a clamp meter because the best way to measure current in mains is with a clamp.
The only problem with clamps is that the specs for the probes are probably not going to be that great with measuring voltage at the low end, because clamps are HVAC / electrical / etc and they they don't really care about tiny voltages.
The an870 technically has better ranges than the ZT-702S and clamp meter, and many multimeters actually use the same chip as the an870 (like the AN8008 or kaiweets kn601, etc) but they can get different specs because they are wired differently.
People like the an870 / kaiweets km601 because it has 4 ports instead of 3.
Technically the best multimeters are around $120, and offer nice features you expect from oscilloscopes like high sample rates for finding peak voltages, etc.
Personally you shouldn't be mediating what he needs, he should be doing this research himself.
Technically if he doesn't know why he needs a multimeter, what specs they need, you could get a $5 meter and it would do 90% of the job (or a $15 clamp meter).
The used market may also be worth checking, maybe you can find a clamp meter that can measure DC for cheap (DC meters tend to be pretty expensive, most clamps only support AC).
*technically clamps are very inaccurate, and physically cannot measure low currents.
A dc clamp sounds awsome because you never need to cut wires to measure currents, but that's not how it works. A dc clamp would only be useful for measuring high currents, like a car battery or solar panels.
unrelated: technically you can measure DC current using an oscilloscope (like the one in the ZT-702S), and you can DIY the clamp yourself. But you also need a bench power supply (like a $30 riden dc to dc + AC to DC supply like a laptop charger) to test it.
Also this is way out your budget, but I feel like I should mention the scope in the ZT-702S multimeter really sucks, and it's sad that if you spend 2x more on a HDS2202s, you can get a portable 200mhz scope with 2 probes (2 probes is much more useful than 1 probe because you can capture a waveform of a different part of the circuit using the other probe as the trigger) + you get a signal generator which can help with finding problems with wires.
BUT it's not a multimeter, it's only a scope. It would be a pain to use as a multimeter.
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Any ideas how they do 5V regulator stuff?
Simplest solution probably is just having high value resistor on bypass/drain pin and feed into zener.

But drain pin probably has low resistance to high voltage, so I suspect that 5V regulator is current mirrors with some high-voltage transistors?
A two-input latch? Depends on the latch. You can if:
>it's an SR latch with both a Q and ~Q output
>it's a JK latch regardless of output
Not sure about D latches. Same should apply to flip-flops.

Note that none of these topologies intrinsically have schmitt inputs, so you're technically better using a comparator IC for this. That or a schmitt inverter, or a latch made from schmitt NAND or NOR gates.

Temperature control is going to be your biggest hurdle. Keeping the temperature high for a short enough time to not get outside the recommended reflow area basically necessitates a half-decent temperature control loop. Use a PID controller, or at the very least slap a thermocouple on the board and adjust the oven power manually and do a few test runs to make sure you don't overshoot.

The 8009 is just a better 8008. The Q10 looks like it's probably better, but I'd look for reviews and comparisons first. Also consider the Fluke 101. It's a name-brand tool with inferior specs (no current mode), but it may well be good enough.

It's almost certainly a pass-regulator, not a shunt regulator. The simplest method is an NPN voltage follower after a higher impedance reference diode, though it's most likely that they use something approximating an op-amp to get a solid output voltage via feedback. This is frequently just an NPN transistor, but for low dropout it's common to use a PNP transistor or even a P-channel MOSFET. Check the datasheet to see how close to 5V you can get the drain voltage before it stops working. These low dropout topologies are less stable and usually require an external bypass capacitor, which we see here, though of course the cap may also be buffering against ripple for when the drain is pulled low. It also needs to be of a topology that can handle negative voltages across it for the aforementioned drain being pulled low, though this can be achieved simply by using a series diode.
Could I make a battery for an older phone with USB-C Interface that can charge while the thing is on? New work wants me to bring my own phone so I'll dust of my old shark fin but the battery and interface sucks
Do you mean you charge this battery with a USB C port? Do you mean this battery is built into the older phone? If so it's possible, but not straightforward. The lithium charge circuit is relatively straightforward, rather the difficult parts will be the output interface and mechanical design.
I have one of these cheap portable oscilloscopes. Was like $100 and very nice. Zeeweii/SigPeak DSO2512G.
Needs to just be decent and cover the usual range of features, rather than good but less features.
This is for a person who has no multimeter at all, or experience using one. They're also fresh from high school.
I'll now investigate an8009 vs q10.
I also heard about a cm81 elsewhere.
Will probably get one of these multimeters + a small kit, and give them one of my breadboards (got a bunch unopened).
Get him a meter where the fuses are cheap and easy to replace. And some spare fuses for it. Accidentally leaving your meter with probes in the current pins is too easy, at least for meters that don't have the feature where they alert you when they're set to a non-current mode when the probe is in a current socket. Some nice Brymen meters have that probe alert feature, check if any of your potential meters have that.

Also see the eevblog dmm spreadsheet.
Ended up with an8009 + a breadboard kit.
Had to order on Amazon because it's needed by next week, else I would have gone with q10 or fluke 15b+ or 17b+ from aliexpress.
Amazon had q10, but it was basically 2x an8009, which itself is overpriced respective to aliexpress.
I'll also throw in a devboard from my collection. I got a shitton of different chips. I'll pick among the ones I have many of.
I think he's going to be very happy with this. If anything, it's gonna be overkill.
What would happen if i removed removed the zener diode from my laptop charger circuit? How will the output behave and can it fry the entire thing?
I don't know much about electronics
>can it fry the entire thing?

zeners are use in 2 main ways.
one is to establish a reference voltage for the output.
if you remove that, you'll get over-voltage to the circuit, and things can burn.
the other way is to cut off the occasional voltage spikes from lightening, or whatever.
if you remove it, likely nothing will happen.

...but, generally speaking, a zener should be considered a crucial component, not to be messed with.
>if you remove that, you'll get over-voltage to the circuit, and things can burn.
That's what i have been afraid off. I am trying to increase the amperage on the output, Mot much maybe one or two amps more, I can solder but i am short on components, is there a way to "overclock" it by removing something instead of adding more details?
>is there a way to "overclock" it by removing something instead of adding more details?

power supplies, like most everything else, are NOT designed with overhead in mind.
the major goal is always low-cost. so, there's no unused capabilities.
to increase current, you can (1) get a more powerful unit, or (2) carefully design a parallel supply to provide the extra needed amps.
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Please help a simpleton with a basic question:
I have a Moroccan immigrant coming to live with me
I want to house him in my toolshed
My toolshed is powered by a 10-gauge wire plugged into a normal outlet on my porch
Breaker for said outlet is labeled 20 SWD, which I'm guessing means 20 amps
The wire to the toolshed is 100 feet long. I live at 9000 feet in Colorado so it gets cold, very cold. I understand that can affect amperage.

My question is, what kinds of things will my immigrant be able to run in the toolshed? If he has a tiny space heater, a lightbulb, and a phone charger going all at once will he burn down my home?
>It's almost certainly a pass-regulator, not a shunt regulator.
Will look into it.
Trying to see how offline switchers can self-power from 500+ VDC rail.

Old chips seem to mostly utilize high value resistors and zeners for self powering, newer designs are a bit more sophisticated it seems.

You likely can't increase output current. Power supplies are designed and specced for maximum output power, there is some bare minimum overhead for tolerances but that's it. If you need more current but not voltage, you can try using buck converter to reduce voltage but increase current.
>If he has a tiny space heater, a lightbulb, and a phone charger going all at once will he burn down my home?
If he has to pay the electricity for all that then yes.
Solution is very simple: don't house illegal aliens.
I don't think anon was serious, anon.
I don't think you're serious, anon. Electric blankets would be better anyway.
>to increase current, you can (1) get a more powerful unit
no i can't. i live in the middle of a desert and packages arrive after three weeks miniumum, if i am lucky.
the thing i am working on will become irrelevant before the details manage to arrive.
>(2) carefully design a parallel supply to provide the extra needed amps.
i know that you can chain them like batteries but the fact that my place has electricity at all is already hard to imagine, i lack everything.
no spare DC sources.
>you can try using buck converter to reduce voltage but increase current.
one of those things could solve all my problems for sure.
but i doubt that i can make one myself.
well i will survive without those 2 amps
thanks for the help
He cold improves the situation. Keeps wires cool.
Lightbulb and charger are negligible compared to the space heater, which is going to be over 1000 W more than likely.
10 awg 20 amp breaker. Probably fine, you could put another 15 amp breaker in-line somewhere if you’re worried about it.
You can always test it with some test loads, I use one a couple of space heaters to do my testing.
just realised that my op has been immortalised in the sticky
i also just realised that there's an erroneous > in the lithium battery link
this feels like a gsnk gag

they use zeners more often yes, but i think they always have to be external due to the heat production. maybe it's an internal zener with a really large value resistor that takes some time to charge up the capacitor, before it gets powered from an auxiliary winding? even a pass regulator is going to produce too much heat just from a milliamp, you can only drop the quiescent current of a switching converter by so much.
The entire battery is the backside of the phone. You click it into place
Is it possible to make your own SSD like device? People always say firmware is secret on storage devices, so couldn't I make an open source hardware storage? Is there anything like that? I've seen people make their own cpus and computers so surely someone has made storage devices?
What in Samhain happened to this Antarctican underwater PCB weaving board?
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I'm working on this three phase motor starter and after about 5 minutes the coil goes open. It doesn't even feel hot. Is it typical for more than wire to be inside these? Like a variable resistor or something?

After about 10 minutes it returns to normal.
I guess, have a look at what flash ICs and FeRAM ICs cost per MB.
>Like a variable resistor or something?

likely a self-resetting thermal fuse.
if the thing is not actually hot, the fuse may be at end-of-life.
Yeah, the fuse is not designed to be tripped all the time. Approximately once, in fact.
Did I read that correctly? That's a lot of energy. Don't forget your safety goggles.
I'm tired of employers who expect employees to BYOD and/or require them to install software on personal devices. If it is a requirement for work, you provide the preconfigured hardware and necessary software.
>Did I read that correctly?
Yeah 18 thousand rpm, or 300 oscillations per second
>That's a lot of energy.
At the moment it's just a shaft and nothing else spinning, but once I add the spin-coater's 4-jaw chuck on it (which is made from a cross of threaded rod), the moment of inertia will be an order of magnitude higher. I don't plan on taking it up to 18k rpm if I don't need to, if only because that would make balancing a very stringent requirement. And with the extra momentum it will spike current too high if I try to accelerate it too quickly. The scary thing is that I'll need to basically be next to the thing while it spins, in order to add the liquid atop it. So it's less the eyes and more the torso that's at risk, though safety glasses will be worn. I'll calculate the amount of energy for my planned rotation rate and figure out how much plywood or whatever I need to protect against my makeshift shuriken. I'm guessing like 20mm of wood, plus some sheet metal.

The other thing I need to consider is the control mechanism. I'm thinking of a spring-loaded slide-pot, though a capacitive PCB slider would be more reliable. Importantly, the thing needs to slow down once my hand has been removed, but not so rapidly to result in current spikes. Actually maybe braking current doesn't matter, since it isn't going back into the rails, and my FETs are rated at like 70A continuous.
I will pray for you.
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How do I measure electromagnetic radiation? Someone moved into the apartment above me and my Windows bluetooth shows at least EIGHT Philips hue bulbs. I see two new Wi-Fi networks, each with separate 2.4 GHz and 5 GHz access points. He's the ultimate consumer. Any ideas how to make sense of what he brought into the house? I thought about measuring EMR? How do I go about that? I already called police and explained the situation two weeks ago and while they said they're going to looking into it they're not doing anything. I'm not going to talk to my neighbor at least just yet because I'm not charismatic enough and he will block me off.
Stop posting on 4chan from your grave, Chuck.
jam the 2.4ghz bands and watch him seethe
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Alright, stupid question: What would happen if I were to heat up a PCB-heater (Copper Trace Resistor) with a bench top PSU on the terminals and then apply a soldering iron (this one: https://www.conrad.de/de/p/toolcraft-jls-03-loetkolben-230-v-60-w-bleistiftform-200-450-c-588269.html) to one of the terminals to melt the solder to suck it up with a pump (this one: https://www.conrad.de/de/p/toolcraft-lee-192-entloetsaugpumpe-antistatisch-2196503.html)?

The reason is that my 3d printer's heating bed shat the bed (pic rel) and the replacement will not be here for a while. I wanted to fix it for the time being. I tried heating the pads with the iron, but the solder became malleable and was pressed in slightly, it didn't melt because the pad literally connects to a heater with 220 Watts of thermal capacity while my iron can only supply 60 Watts ...
What PCB color do I get?

Green is slow
Purple is ????
Red is fast, but will catch on fire
Yellow is unreliable
Blue is good
White is right, white is good
Black is bad
>PCB color

/lgbt/ will be able to answer this best.
Slap a decal on for the silkscreen and clearcoat it.
That question is serious, since moment you use solder mask, you change destiny of the PCB. Making it pink, for example, will certainly make it suicide.
Pink PCBs have a 41% critical failure rate and scientists can't figure out why.
green because it tickles my nostalgia. as a child i loved to take apart old appliances to play with PCB's
I've an e-scooter.
It has 36V battery (10S) and it does 44 km/h (no load) and around 32-33 km/h with me going full throttle (maybe, idk, too scared to see how fast would it go kek).
And I've fucked up a battery (did a small lil hole in one of the cells trying to disassemble the thing).
Then I realized that I don't go any faster than 25 km/h and on 24V (7S) it would go 30-32 km/h no load, and maybe 25 km/h with load.

Question is, would it run more efficiently at 24V? After all, it has dumb square wave BLDC controller, and it is basically a glorified DC-DC converter, and I think that with lower difference between motor BEMF and battery voltage it would run much more efficient.
Not to mention that I'd have less losses in the battery as ESR would be lower (7S4P instead of 10S3P) which might give more/same mileage despite having less capacity.
>ecb BJTs

>Yellow is unreliable
please elaborate

Efficiency is usually somewhat higher at high voltages, because the ohmic losses (for given wiring and inverter) get lower for a given power output. But you're right that the ratio between BEMF and cell voltage makes a difference too. Ultimately these are just current spikes in the FETs, so you can probably calculate the losses at certain voltages if you have the Kv rating for the motor.
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>Efficiency is usually somewhat higher at high voltages, because the ohmic losses (for given wiring and inverter) get lower for a given power output.
If motor is wound for that voltage. But I think it is not the case here.

There are two things in motor that are important. Torque and speed.
Torque is a function of current, which is limited by controller. If I keep 15A current limit, it would accelerate with exactly the same rate, until difference between BEMF and battery voltage drops to the point it can't push said current.
Speed is just a function of voltage.

When it comes to the current, losses in the motor are exactly the same (since both copper and iron losses are function of current iirc), but losses in the battery would be lower.
When it comes to the losses at 25 km/h... I dunno. I think that controller that works as a commutator (i.e. duty cycle is 100%) losses are smaller than when it works as synchronous buck converter (i.e. duty cycle <100%). And I think that buck converters (e.g. pic related) are more efficient when Vin is close to Vout. Which again, is better, since BEMF at 25 km/h is probably very close to supply voltage.
>Ultimately these are just current spikes in the FETs, so you can probably calculate the losses at certain voltages if you have the Kv rating for the motor.
KV of the motor is approx 1.0602 km/h per volt. A bit higher probably, because I've adjusted speedometer so it is a bit more pessimistic than reality.
But then idk the inductance of motor or frequency of the controller. I don't even know the resistance of the motor.
So its kinda hard to calculate absolute numbers, and relative numbers - idk either
>please elaborate
reminds me of shitty 00's AMD socket A boards.
Other thing, are FOC controllers more efficient? Because switching losses in them should be higher than in dumb square wave, but everyone tells they are more efficient, and all big industrial motors, no matter induction or perm. magnet, they use FOC inverters. Why is that?
>Why is that?
3-phase AC delta/wye
fuck, its really complicated, especially since there are different motors, some have sine bemf, some have trapezoidal... And idk wtf chink motor is since I've no scope, and i dont really want to blow up a laptop sound card.
>If motor is wound for that voltage
A motor isn't really wound just for a voltage, it's wound for a voltage and speed. A BLDC designed to run at 12S for drone use will want to run at a lower voltage if used as a direct drive hub motor, as I personally discovered recently.

>but losses in the battery would be lower
At a lower voltage they'll be sourcing more current for the same power output, battery losses will be the same.

Ultimately, as you increase the voltage, the ohmic losses in the wiring between the battery and driver get better but the switching losses in the transistors get worse.
When going for a lower voltage, either find yourself speed limited or torque limited. It's reasonably easy to measure the torque/current proportionality constant yourself, I strapped my motor to the top of my door, connected power resistors across its windings, and used it as a pulley for a weight to drag down. The motor got to a constant speed and I measured the voltage and frequency across the windings, which I could convert into speed and current values for the known torque.

They provide more torque for the same amount of current since there's less ripple torque. Team TMC4671 here.

Get an op-amp and a couple of optocouplers to make an analogue optocoupler for sound-card protection. Or get a USB sound card and USB data isolator cable. Or buy a cheap shitty handheld scope.
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I just realised you could get good cheap soldering irons by making a box that measures the resistance of the heating element and TRIACs them for temp control. In order for the iron to heat up nice and quickly you'd get 110V irons and run them at 220V, because you're measuring their temperature via the element resistance there's no risk of the element burning out. It would mainly be useful in 220V countries, but I guess it also works where you've got 2x110V sockets like for a welder.

Bet you could make such a box for like $25.
minor soldering mishap
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>At a lower voltage they'll be sourcing more current for the same power output, battery losses will be the same.
Yep. But overall power would be lower.
With 36V, its 540W, and with 24V its 360W, since can't really push much more current into the motor, because this happens even at stock motor currents.
Well, you can power in the controller, but it all options suck. Current limit will limit torque, and that sucks. Other option is to limit speed, which also sucks as it is quite abrupt and annoying.
>When going for a lower voltage, either find yourself speed limited or torque limited.
Given scooter has excessive speed, speed limitation isn't such big deal really.
So overall I suspect that efficiency improvements will mainly happen due to lower power (which can be achieved other ways), and slightly decreased switching losses (prob 5% improvement)
>Get an op-amp and a couple of optocouplers to make an analogue optocoupler for sound-card protection. Or get a USB sound card and USB data isolator cable. Or buy a cheap shitty handheld scope.
I've a better plan. How do I blow up an oscope in uni in such way they won't bother fixing it, yet I can fix it later on?

Unless it uses PTC heater, you won't be able to determine resistance precisely enough to have any meaningful control, furthermore, chinese 936 box is like 20 bucks or less, or some CXG iron is like 10 bucks. Why suffer?
>How do I blow up an oscope in uni in such way they won't bother fixing it, yet I can fix it later on?
I got myself a free scope from the uni through less duplicitous means (it's a hybrid CRT scope they didn't want to spend any more money on getting calibrated yearly), but you do you.

>Unless it uses PTC heater
Aren't all shitty open-loop irons PTC-based? Even if it needs calibration I think it should be doable.

>Why suffer
So I can turn this Yihua 929DV $15 desoldering sucker iron into one that doesn't melt my solder mask off and take 5 minutes to get hot.
What is this kind of part called? Is Tailpipe the only name for it?

Also if anon knows any similar clean options for a cord leading into a case
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stupid, but funny, name.
normies would call it a cable strain relief.
Those screw-on cable glands are quite nice and really do provide good tugging relief, but they're not as good for angle relief as your pic. Personally for my last project I just tied the wire in a knot and fed it through a chamfered snug hole. 3D printed TPU can probably make for decent strain relief.
>Aren't all shitty open-loop irons PTC-based?
Some heaters are thin film PTC (resistance increases, power drops, some irons do use this resistance to control temperature btw), some heaters are nichrome, and they barely change their resistance and thus power stays the same, and in case of 936 irons, if you don't control the temperature, heating element will heat up iron to cherry hot without any issues, and then die from overheating.
> Even if it needs calibration I think it should be doable.
Only with PTC. With nicrohome heaters you'd definitely need thermal sensor of some kind (usually thermal couple).
>So I can turn this Yihua 929DV $15 desoldering sucker iron into one that doesn't melt my solder mask off and take 5 minutes to get hot.
This one is nichrome heater and temperature is determined by how much does tip stick out and power of the heater.
Since you can't get temp feedback, your best option is to use a triac dimmer, and let iron sit for a while, and measure the temperature at the tip. If it is more than 350C - lower the power, if it is less than idk, 320, increase the power. Maybe you can make PID control of some sort, but response will be really slow, so idk.
Strain relief?
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grommet with strain relief
Ah. Well even then I could still measure the resistance change of nichrome without too much difficulty, a shift of 0.5% would be measurable without too much difficulty.

>This one is nichrome heater
I figured they had some sort of PTC wire instead of nichrome.
>temperature is determined by how much does tip stick out
So the element itself gets up to temperature quickly and without risk of overheating, while they rely on the high thermal mass of the element or tip and the moderate thermal resistance from the element to the tip to "regulate" temperature? Like a thermal RC filter. Sounds awful, but I guess PTC films are expensive or difficult to work with. And because of that deliberately high thermal resistance from element to tip, it's impossible to make the tip heat up substantially quicker if I kept the element below ~500C anyhow.

Guess that idea is useless then, I'd be better off buying tips and handles for more expensive soldering irons and making custom stations for them. Like what the Aixun T3A does.
thank you anons
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Im an idiot.. This USB cable has 5 wires. I want to wire it behind a usb-b male connector but theres only 4 points on it, so I assume the last one is ground. Where do I solder that one? Why do some cables have ground and some dont?
The fifth wire is the cable shield which in this case is the same as ground.
what do I do with it? Just ignore it or tape it away?
Tie it together with ground if it isn't already.
Why do they often completely separate ground and shielding? Why spend extra money for an extra wire? I've even seen a device which obviously used the ground of an USB cable for an extra signal, and used the shielding for ground.
could also be the ID pin which isnt commonly used
>got an idea for a project
>spend months researching every aspect and learning theory
>dig a few rabbit holes in between
>order parts
>sort parts in boxes, mark, pack, and store everything
>get into one of the previous rabbit holes
>got a new idea for a project
>spend months researching every aspect and learning theory
>dig a few rabbit holes in between
>order parts
>sort parts in boxes, mark, pack, and store everything
>get into one of the previous rabbit holes
does anyone know the feel? how do i stay focused on one and just one thing?
recognize bad habits and stop doing them
i.e. basic self-awareness
>how do i stay focused on one and just one thing?

your happiness comes from flitting from one project to the next.
why change that?
you'll just make yourself miserable.
like the rest of us.
>With 36V, its 540W, and with 24V its 360W, since can't really push much more current into the motor, because this happens even at stock motor currents.
Bullshit actually, I did some research, and apparently all motor controllers try to maintain phase current, not DC bus current, so on 24V it would consume a bit more current to get to the same phase current.
But duty cycle of the PWM would be higher thus more efficient.

Sodium Ion batteries are real.
>Pride Month
is there a way to make kicad DRC shut the fuck up about thermal vias?
oh wait nevermind im a dumb nigger, i had a pour going to a single layer rather than multiple layers.
based. energy density?
Shitty 18650. "9800 mah" tier.
It’s an IGBT/LGBT joke, pride should remain a sin.

Still worth doing for low-cost use where density doesn’t matter, like home storage. Hope they don’t stick to the tiny cylindrical cells though, they should be making larger prismatic cells like they do for LiFePO4.

Can’t watch the video at the moment, is it a nickel manganese cobalt design? If so that’s still a bottleneck.
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>Still worth doing for low-cost use where density doesn’t matter, like home storage.
If they would improve tech a bit, it would be viable for EVs and such.
> Hope they don’t stick to the tiny cylindrical cells though
Cells can be manufactured in any shape or form.
I think at the moment, some noname cell wrapping facilities are making these cells, and they might only have equipment for 18650s. (pic related, you can buy catode material)
>Can’t watch the video at the moment, is it a nickel manganese cobalt design? If so that’s still a bottleneck.
Unknown, but it very likely not lithium, and probably NMF... Dunno chemistry at all.
Discharge voltages don't fit any lithium battery and it doesn't have typical lithium battery "shelf" where voltage barely changes. It has somewhat linear discharge from 4V to like 2.4V and then it drops off to zero.

I'm kinda glad that this is no longer a technology from shitty eco-brainwash youtube video, but something you can buy and try out, albeit a bit expensive atm.
Nah I am still miserable. There are ways.
i'm trying to make a motor controller using the TI DRV8323. it states the input is 6-60V. how does it generate the gate driver voltage? i understand it uses a charge pump on the high side, but how is it dropping the low side voltage to the typical 12-20V absolute maximum for most NFETs when its input range is 6-60V?
Hmmm... It's a bit more spicy pressure-wise, but less spicy fire-wise.
I wonder if these cells are defect with broken vent cap?
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Looks like the low-side gate driver's supply voltage VGLS comes directly from a linear regulator tied to the input voltage VM. I imagine VGLS is hence capped at no more than VM, as it often is with these monolithic gate drivers. If you do use at VM < 10V, I'd want to use logic level power MOSFETs. It also seems to use only a single charge pump for all three high-side drivers, and no bootstrap caps, which is unusual. VGLS also isn't being fed into this charge pump, so I guess it's somehow self-regulating even at high VM values. If you're lucky you'll get a higher high side drive voltage than VM, not that it helps much. Not too fond of the lack of a traditional bootstrap circuit, I hear it's more likely to give a spike of excessive gate voltage like that, though if there's an internal zener I guess it's fine.

The 1A gate drive is ok, but without the external bootstrap cap there's no external high-side power rail on which to slap a ZXGD300x. That's why I'll probably go for a DRV830x or equivalent Trinamic 3-phase gate driver IC, in conjunction with a TMC4671 FOC controller. Current sensing will be a pain.
why did you call this thread "Pride Month edition", what does September have to do with groomers? I thought they just "claimed" June?
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Why is A. works just fine, but B. throws out 'convergence error'?
because simulations always need a well defined ground
put the ground node somewhere, anywhere
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wtf are you even trying to simulate anyways, how is that feedback loop supposed to work?
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Constant current LED driver.
The op-amp drives the MOS to achieve a currenty through the 500m resistor set by voltage divider on the non-inverting input.
If the input voltage increases, the op-amp throttles the MOS to maintain the same current, and vice-versa.
You can also do it with a BJT as pic related, but this uses the BJT's BE Vf as the control voltage. An op-amp offers more fine control.
when I tried simulating it (using magic ideal parts) i was getting 20v-kilovolts at the OpAmp's output. Try adding a feedback resistor of some sort from output to the base of the 1k resistor for stability.
I think that battery doesn't provide enough voltage and thus op-amp sends output of mosfet to stratosphere (since this is how ideal parts work, they just use an op-amp equation with no voltage limit) and it keeps on growing, which simulator doesn't like and gives you a convergence error.
Anyone have any recommendations on a hotplate for SMD soldering? I have no idea what to look for.

Also related question; Anyone here ever try making one of these DIY hot-plate PCBs? I find it kind of interesting.
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Forgot pic
can't you just buy one for cooking? how hot do they even need to be
I asked this in a qtddtot but I think this may be the better thread
Can someone explain to me why devices on a L1 or L2 bus share wire numbers?

Shouldnt you be able to differentiate between lines? If you have multiple switches/buttons with power from the bus, how are you supposed to troubleshoot? Most drawings have the return wire labeled, why not the outgoing L1?

In pic related, shouldnt each button have a specific number on its left side?
Because I had a picture of an IGBT that I wanted to use for the op pic, literally no other reason.

I bought a cheap aliexpress mains hotplate and designed a PCB for TRIAC PID control. But I'm kinda retarded when it comes to design and it's sitting in development hell after somehow frying a MAX6675.

PCB-based designs are unsuited to handle soldering temperatures for minutes on end, as some on youtube have discovered. You're better off buying an off-the-shelf silicone or ceramic heater, sticking it to a flat plate, and embedding a thermocouple somewhere. I recommend just buying a mains temperature controller that's capable of changing the set-point via an internal custom program, or via a connection to a computer or MCU. Pretty sure PID controllers often have an ethernet or RS232 connection. Optotriac and zero-crossing circuits are a pain.
>shouldnt each button have a specific number on its left side?

if it did, it would mean the person who did the drawing is a maroon.
all the LHS wires are joined together, so they get all get the same number.
on a PCB or a schematic, the collection would be called a net, and all would be called NET 666, or whatever.
coz of logic and common sense.
I understand this in theory, but why does every single control panel I see have every wire on a bus labeled? And what's the method of this?

These labels arent on drawings, so how do people label these? Especially neutrals. Shit should just be all labeled N, but they always have specific labels
So you can check the neutral bar and find the one terminal for it or whatever. The neutrals are probably labeled by their position in the strip.

You have to read the age of labels and depth of the wire in the pile of shit too, it'll give you more clues on whats what.
So, you have a neutral "bus" and L1 "bus", each their own collection of let's say 10 terminals each. This doesn't need to show on the electrical schematic?

You can just label them TB-1, TB-2, etc? So for a button, you'd have one side with "TB-1", and the other side with the wire number as seen on the electrical schematic. How does one know then if all those items are on a bus or simply jumped in field?
are there really bots on /diy/? i can see that being a good idea for /g/ and the red boards, but this board is slow even if it has bots
>i can see that being a good idea

Stupidest idea that ever got spammed here. On that day, in addition to all the normal shit that normal idiots will post, we'll have a million idiots calling everyone else a bot.

In other words, 4chan at its best; idiots competing for the idiot of the day award. so keep spamming your pathetic idea.
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is there a way to force an ideal choice for conflict net classes in kicad? im doing low side current sensing. i have a net labeled "SNA" but it bitches at me about a name conflict and forces it to "GND". i want to manually assign it to "SNA" to make pcb layout easier.
When schematic is drawn as shown - it's all logically and electrically same net. So it does not make sense to label each wire separately.
If shit goes somewhere off or there is some terminal block on bus as splitter - it should be shown somehow in schematic and potentially each segment getting it's own net.

There are standards that would enforce labelling each wire segment but it's generally not enforced for industrial applications.

use net tie. I think kicad allows creating net tie components - custom footprint, two pads and join them together.
Alternatively - either some jumper resistors or rename GND to GND_SNA or something similarly retarded
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i have this t212 hammond organ, works fine but its not valuable or anything. i was planning to take the leslie unit out and make it a standalone speaker cabinet, but now im wondering if i can just pull all the amplifier guts and make it powered. i know theres tons of stuff online about modifying organ amps, but i cant find an answer as to simply deleting all the keyboard stuff and hacking in a line input...any one know about this?
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>can just pull all the amplifier guts and make it powered

you have the opportunity to replace that ancient monstrosity by a super kawaii Lepai LP-2020A, and you are hesitating.
something wrong with you, boy.
do ohmfags really?
interdasting, so with that thingy i can feed in a guitar signal and send it to the leslie, you reckon it will sound well enough huh?
>guitar signal

i dont know much about guitars.
seems they can put out as much as 1V but need a high impedance amp, like 1meg.
so, likely you'd need a pre-amp, maybe just a pedal preamp.
the Lepai, like just about every amp, has an AUX input, which means a signal about 0.1Vac
You might need a DI box.
ok ty sirs
guitar has a Vppk of 50-400mV and output impedence of 100k or so (might actually be 10k, they define "impedance" as what load they can drive so probably closer to 10k)
So let’s say the output impedance is 10k ohm.
Is there any harm or negative effect of driving a 10 M ohm FET op-amp preamp??
Perhaps an impedance matching transformer. I think that might be too many turns though and have other negative effects.
>Is there any harm or negative effect of driving a 10 M ohm FET op-amp

shouldnt be.
in fact, it should sound better as 10K/100K input impedances tend to attenuate the high frequencies.
the one advantage of lower input impedances is you'll get less hum if the cable is inadequately shielded.
>want to rewind mot for 24vac
>need 18 turns for the right voltage, seems easy enough
>normal dc power cable has insulation that's too thick
>consider multiple parallel windings of enamel wire
>the thickest stuff i can easily get is 1.25mm diameter
>do the math
>would require 20 windings in parallel
i really don't want to spend a dozen + hours of my life making 360 turns through a closed core
It would take less time than knitting a a scarf for your mom.
You can divide down the time by computing the length and twisting, say, 4 pairs at a time with your drill. Also, you have litz wire! You can use higher frequencies than 60Hz with fewer losses.
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ligma nitz, litz
I'm thinking of doing some Welding at home. How should I go about modding my home's power to mainly account for a Vulcan ProTIG 165? Curious anon.
I also have a 110v S7 Stick Welder at home - but sadly it's maximum amperage is only 113 amps (actual - because it's one of those "muh heckin' 200 amperinos!" but in reality it only displays double the actual number - which is retarded).
>You can use higher frequencies than 60Hz with fewer losses
I'm modifying a MOT because I want to see how cheap I can get an EDM PSU, and because I want a low-effort power supply as a test rig for my kW BLDCs. If I wanted to bother designing a 2kW off-line AC-to-DC converter I'd just buy a nice toroid.

That said, 24V (48V with split rectifier) is kinda low for an EDM PSU, so maybe trying to get a supply to do both the motors and the EDM is silly. For the EDM PSU I could go for whatever is most convenient, in this case it would be using the entirety of a 9m roll of 1.25mm cable for each parallel winding.

Ask the sqt thread, metallurgy/machining thread, or welding thread if there is one. My guess is you want to plug it into a conventional 240V outlet (electric oven outlet for americans), if not a specifically high-current outlet variant (15A, 20A, etc.).
Read the welder's spec sheet too.
Will do anon.
>110v S7 Stick Welder

i have something similar. it has a 120V/240V switch, but it's useless at 120V.
since i dont wanna unplug my stove to get 240V, i made something similar to this.
except the female is just a normal 120V-looking female from an extension cord.
you need to connect to 2 diff power sockets, each on a diff phase.
you'll prob find some like that in the kitchen.
>found dead laptop battery in the trash at home that I stole from e-waste trashcan 5 years ago
>3/4 cells had 3-3.6V
>1 cell had 1.17V
Made me think, is it worth making an automated recycled (or maybe chink) battery tester and matcher?
A device that can charge cells, discharge cell (and instead of heating the air, charge other cells under test), measure temperature and all this while logging voltage, current, time and temperature?
You put in cells, on the end it tells you the capacity, ESR, temperature, or if cell is junk. And with some software magic it can build a battery pack where all parallels are matched as close as possible.
All commercially available solutions suck as they dissipate energy as heat (imagine wasting free energy) or don't log as much stuff, and don't talk to computer.
In general, a device with DC-DC converter per cell, in order to either provide energy to DC bus, or take energy from it, kinda similar to what active battery balancers do. And bunch of op-amps with micros to talk via I2C or UART or idk, whatever bus, waiting for commands.

Basically, an industrial grade equipment that is probably used at battery factory, but modular, programmable extensible and

Just add whatever circuit a welder might need.
I've bought similar chinese box too. I did pop IGBTs in it, and stopped trying to turn in into a lab bench welder.
I think it's worth doing if you get a lot of those cells. Make it take like 8 cells at once, perform charge-discharge analysis on the lot. Then you could use that data to properly match them in new packs.
>a device with DC-DC converter per cell
It's a lot more complex to have a DC-DC converter for every single cell, as opposed to just using BJT+opamp current sources and sinks. I'd just bond the heat-sink to something that could benefit from heat, like my hot water cylinder, some desiccant that needs drying, or maybe a biltong box.

>programmable extensible and
and what?
>I think it's worth doing if you get a lot of those cells.
Pretty much yes. If you have three cells, that's three cells, you can't even optimize a 2S pack that much lol.
> Make it take like 8 cells at once, perform charge-discharge analysis on the lot
I was thinking of a device that can do it just to one cell, but it has the DC bus connector, and data lines, where it can dump/take energy and well, receive commands. And a master device, that has a big ass power resistor (in case if all cells are charged), power supply (in case if all cells are dead), and whatever interface to usb converter.
>It's a lot more complex to have a DC-DC converter for every single cell,
Yes, but for example, that's what Lii-500 does, at least for charging. And it is possible to use bidirectional DC-DC converters. Or it might be cheaper to use step-up for discharge and step-down for charging, idk. That's a bit unclear what to do, but it has to be DC-DC, otherwise its kinda lame... Unless its winter lol.
>programmable extensible and
>and what?
Lol. I probably means programmable and expansible/scalable or whatever.
If you have like 50 cells then it's going to take ages to get through them by swapping them out every 4 hours or whatever one by one.
>dc bus
do you mean to have a storage battery?

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