/diy/ - Do It Yourself

>>2618609 #
Yep, they are burnt cause there was like 5 amps going to the output when I tested the current limiting wo. resistor connected.
I cant find any manuals on the PSU unofrtunately. I only know that it was a DIY kit from 1983

>>2617933 #
Among the items he gave me was this weird "NC charger".
Its just a regulated PSU with current limiting. The current control is some kind of switch with the slides switching different resistors. Unfortunately it's broken.
>So I thought I could replace it with a potentiometer.
>Just how do I connect it.

no clue what the 3 pos flip switch with the marking "1/20, Auto, Reset/Duration" on the left hand side does.

>>2618603
Guess I'll do that. The only ICs are an LM 324 and CD4060. Power Tranny TIP140

Just how would you achieve such feedback loop circuitry with such miniscule amount of active circuitry? Any good similar example circuits for the LM324?

I'm basically a noob and know almost nothing about OP amps.

err. I guess this is what I'm looking for?

>>2618620
Thought you guys may get a chuckle out of this. I was stuffing a pillow between my bed and nightstand to stop the dog from eating the cable and this eventually happened.

Came very very close to shocking myself.

>>2618678
> Be bongland millennial
> design circuit using retarded eurostandards
> doesn’t work, consult greybeard in basement
> “you were missing a resistor, I fixed your schematic for you”
> enlightenment.gif

>>2618649
>no clue what the 3 pos flip switch with the marking "1/20, Auto, Reset/Duration"

if it's a charger, then possibly you can set a time limit so it doesnt burn out the battery.
just like women, they tend to get very bothered if you keep pumping juice into them once they're full.

Oh god, so the polarity band on a tantalum cap signifies + while it is cathode (-) on the diode? That's just vile.

>>2618346
Ok replace R3 with a wire, and move the button so it pulls U1 pin 12 up to 3.3V. That should do it.

Be nice to have a DMM that does frequency and duty cycle, maybe I should make a little handheld tester.

>>2618465
Well I designed it wrong.

>>2618778
>Well I designed it wrong.
We at apple would prefer the term "holding it wrong"

>>2618670
they try to use the output to make both inputs the same

>>2618670
>>2618835
>they try to use the output to make both inputs the same
Only when they have a negative feedback loop. This can be direct or indirect. Note that while usually this is a path from the output to (-), this can also be a path through an odd number of inverting elements (e.g. common emitter amplifiers) and back to (+) instead.

When they don't have a negative feedback loop, the output will hit a voltage rail. This is the positive most rail if the (+) is larger than the (-), or the negative most rail if the (-) is larger than the (+).

>>2618678
It's ok, but OP3 is tripping me up. The lack of a proper differential amp on the current is also sub-par, and the positive feedback present in OP2 means it won't be very linear when switching between CC and CV modes. I prefer dual-diode based circuits, with gain-limited error amplification with some capacitors in the loop for stability.

>>2618620
I want to science for myself, OP.
Is that enough? For me it's a hobby. I like science. I could be good at it, but to be honest, it's crazy expensive to do correctly.
I have an experiment in mind but it will cost $250 to make and about 47 hours of work to complete. I'm broke, so this is a real problem for me. I would rather not take out loans to do my own science. That would be unscientific, IMO.

>>2618867
Consider getting a job.

>>2618778
>replace R3 with a wire, and move the button so it pulls U1 pin 12 up to 3.3V
Yep that did it, and I guess there was no other issue either, since it works fine now. I found it surprising how forgiving strip-board is for changing the netlist. But I guess when having long jumper wires is natural it's not that different, worst case you just need to find a spare strip somewhere and cut it from the surrounding copper, then run new wires to it. Leaving room for components near your power rails helps.

why does only china make plug-in capacitors for your home? the reason i need one is to stabilise the voltage when inductive loads start running

>>2619041
This is /diy/
do it yuaserefu

>>2619041
>stabilise the voltage when inductive loads start running

that's a good strategy on DC where the cap operates as a short-term battery charged to Vcc.
but it doesnt do a damned thing on AC when the line voltage is constantly bouncing around.

the only possible utility is to bring the power factor closer to 1.0 so you save money.
but that only works on 3-phase systems.
and the caps you find inside are so fracking tiny, they're 100% useless in any situation.

how can I learn if the designs I come up with are retarded or not
they more or less do what I want but I can't tell if they would qualify as "good" for a production sense, or if they're just fucking stupid implementations, or whatever

>>2619095
Without knowing what you design how is anyone to offer useful advice?

The oven is now happy with DC.
It seems like one element is getting much hotter than the other and idk why that would be but no good way atm to measure ohms.
Also the thermostat doesn't seem to work, really confused as to why.
I can just replace it with a k type thermocouple board though
Still waiting for replacement timer switch though ow I should just go with an electronic controller desu.

>>2619091
The power correction capacitors on large industrial motors are surprisingly small. They usually look like slightly larger versions of those caps you find in microwave ovens.
The black epoxy caps you find in these power savers are for starting small single phase motors in the right direction—you usually see them on things like fans for your home.
If billing us for having a bad power factor was worthwhile, we’d all have 3-phase power to every home (for our massive inductive loads it would make sense)
I live in an area where I run a big motor for 8 hours a day in the dead of winter, but my furnace died and the new one is a DC motor so I no longer need it.

>>2619095
>how can I learn if the designs I come up with are retarded or not

consult your sifu.

>>2619100
in my mind, "good circuit design" would encompass design principles and patterns that go far beyond any one circuit or circuit type, so I figured there would be advice even without specific circuits.
Also, when people post specific designs as examples, others usually wind up getting lost critiquing just that specific design instead of giving advice on the whole, and the original overarching question never gets answered

with that being said, here's a particular design
tiny url dot com slash 2j8nly64
It's a mostly-analog multiplexer I'm designing, to multiplex 16 band-passed audio signals into one LM3916 LED VU driver so that I can have a spectrograph without needing 16 LM3916s

>>2619102
Brilliant, low-loss soloution!
The (el-cheapo) thermostat is the thing on the left? It doesn’t appear to be in the loop.

>>2619102
>no good way atm to measure ohms.
if you don't own a multimeter you're not welcome here
even one from harbor fright would be sufficient

>>2618713
That's not good. Not good at all. No sir.

>>2619110
I moved the thermostat to switch the 12v side that powers the contacter.
>>2619112
I own 6, I actually have one which is analog but the battery is fucking dead. I was using it for voltage earlier, I guess I could measure the voltage drop at the halfway point but I don't care because I found other problems

>>2619110
Oh thermostat is bottom left, middle left is a rotisserie and middle right is a convection fan

>>2619132
>I moved the thermostat to switch the 12v side that powers the contacter.
That's the proper way to do it. What problems are you having now?

>>2619138
The thermostat doesn't work lol.
I just replace it, probably it was become bent prying the connectors off of it.
Or possibly it requires the full current to pass through it to work correctly.

>>2619102
The elements might not be identical i.e. one is 2kW and the other 3.5kW.

>>2619148
Disconnect one heating element just for shits.

>>2619155
I retained that actually, can switch it between broil and bake. But not while powered or if will start a massive fire.

>>2619166
Does your 12V supply have enough ass to fully close the contactor?

>>2619169
Easily, it will close at 8v and I've got 13

>>2619170
Aside from a loose connection or burned up wire, the only thing left is the thermostat.

>>2618713
>>2619129
Switch off socket's disjunctor; pull leads out with plier; switch disjunctor back on. Done.

I want to connect a thermal fuse to a ptc heater. Dumb question I know but do I just run the ground line through it?

>>2619209
Couldn't find the disjunctor and don't have any pliers so I just pulled them out with my teeth.

I have a headache.

>>2619209
I just carefully used needle nose pliers. I ain't no pussywussy.

>>2619095
There's a few things that can make a design, that seems like it would work on the surface, retarded.
>some component eats an absurd amount of heat
>some component has to react absurdly fast
>some component has to have an extremely precise value
>some component needs to be overly idealised and can't exist in reality
>some active components need to have zero temperature drift
>some active components need to be very well matched
>your power supply needs to be extremely accurate or low-noise
While simulation will sorta make you more robust against these, ultimately you need the experience of looking at and designing other circuits to see where problems could arise in the first place. Adding stray impedances, using accurate models, and adding slight mismatches about the place may help you understand what's prone to go wrong. But testing IRL is the best way to see what does and doesn't work.

Then there's the other type of retarded design:
>there is a far easier way of doing the exact same thing but better
Easier AND better is a requirement for this category. Nothing wrong with making your design more complicated if it improves the specs, and nothing wrong with making your specs worse if it becomes simpler, within reason. But often things are made overly complicated, and worse, compared to existing designs. Often this manifests as using discrete ICs instead of a microcontroller for no good reason, or trying to repurpose a part that really wasn't designed for what you're doing. That said, deliberately obtuse projects can be fun, so long as you don't mind the challenges that come along with it. Some examples include:
>using a VFD as a vacuum tube amplifier (and a VU meter at the same time?)
>using a quartz window EPROM as an image sensor
>using a PIR motion sensor as a non-contact thermometer
>transmitting data between rooms by installing modulating and receiving circuitry inside light bulbs
>anything involving vactrols

>>2619106
>"good circuit design"

- would not use LM3916s, or any other component that's been obsolete for like 15 years.
- would not use individual analog switches, choosing instead an analog MUX like the 4051.
- would not waste a whole bunch of op-amps with a gain of 1, when a simple resistor does the same job.

>>2619285
>would not use LM3916s, or any other component that's been obsolete for like 15 years.
why

>>2619285
bruh
see this is exactly what I meant
how do you think you model an analog switch IC in software that doesn't have a dedicated analog switch IC
that's why it's a MODEL of an analog switch IC
the real circuit will be using a dg408

>>2619285
>would not use LM3916s
Is there a good replacement? Besides using a microcontroller and a sufficiently fast ADC, which would probably turn out to be more expensive.
>individual analog switches
>op-amps with gain of 1
I think everything in the "Analog Switch Model" box is meant to be a single IC like the 405x.

Also 405x series MUXes have been obsolete for like 15 years, use a DG4xx series or DG6xx series, maybe MAX46xx series. In anon's case a single DG406 would multiplex all 16 channels, with excellent off leakage current of 0.01nA compared to its on resistance of 60Ω. For $5.

>>2619306
>dg408
based DG series enjoyer

>>2619308
oh holy based I didn't notice the dg406 had 16 channels, I'll use that instead

>>2619304
I'm not sure considering the braindead moron suggested a fucking fossil of a chip in the 4051

I have an entire tube of lm3916 and lm3914 just laying around anyway
>>2619283
Thank you for understanding what I was trying to ask. I'll take all of this to heart, it's exactly the kind of advice I was looking for.
>>using a quartz window EPROM as an image sensor
please I'm trying to get my current project done, I don't need to get distracted

>>2619308
>Also 405x series MUXes have been obsolete for like 15 years

digikey has them by the 10's of thousands.
really obsolete (like LM3916s) means you can only order (fakes) from China.

>>2619313
Yeah I was designing a sample+hold circuit a few years ago, and realised the 4051 was way too bad to use for it with any size capacitor. Too big a capacitor and its high ESR wouldn't charge it all the way in the narrow charge window, and too small a capacitor and the leakage current would discharge it too quickly. No sweet spot at all.
So I made a spreadsheet out of all the analog mux ICs I could find. The DG506 is another mux with 16 channels, but it's got worse specs in general so I've no idea why someone would even use the DG5xx series aside from for the higher voltage. Pic related.
>Dist - the product of Ron and Ioff, the quantity being sorted by
>Max Dist - the product of Ron max and Ioff max
>Seperate A/D - analogue and digital rails are seperate
Rest should be self-explanatory.

I hate when I have to order just one part from Mouser or Digikey but have to pay almost as much for the shipping as for the part. What are some generally useful things that I can use to pad my orders?

>>2619368
Consumables like chemicals, desoldering wick, various wire, connectors and sockets, and tools/equipment you've been meaning to replace or upgrade.

>>2619368
Bunch of RP2040s and a few Pi Pico boards? Get some nice ADCs and DACs while you're there, plus the specific passives and other supporting components to go with the RP2040s. An ARM programmer is a good idea too. I'd also stock up on MOSFET gate drivers and a nice selection of modern FETs for generic power projects. Don't forget some that can switch rectified mains.

Get some nice low-temp bismuth solder for sensitive components too.

Last thread an anon (>>2616630) mentioned the μΑ723. Can someone tell me how this works? This is just a linear regulator (with more accessible feedback) from what I understand, but apparently it's used inside switching converters?

>>2619368
always keep a notepad full of gadget's you'd like, and always take inventory for shit that's low

>>2619368
Just buy more.
I have something like 500 0201 decoupling capacitors because I needed 4 and buying 500 was 10usd.

>>2619407
It was probably one of the first ICs to use a bandgap voltage reference, as David Hilbiber worked for Fairchild at that time.

The μΑ723 is basically the “regulator” part of a voltage regulator without all the built-in power transistors and bullshit, as such, it was the go-to when you need characteristics of something that deviated from, say, the 78xx series.

As you mentioned, it is more flexible than those pre-packaged things, so usually “pro-grade” supplies, often switching ones, used it heavily.

>>2619532
Ok but how does it oscillate? I understand how it works as a voltage reference and as an error amplifier, but not as a PWM controller. Or is it just a self-oscillating buck due to R4 giving it some hysteresis? If so you could't make boost circuits, so it feels pretty inferior to an actual PWM controller like the TL494, and a lot more obtuse to design circuits for. Or maybe current-mode boost would work? With compensation to handle high duty-cycles?

>>2619091
but i think improving power factor is effectively the same thing as a decoupling capacitor in a DC circuit. that's because the lag and lead of the voltage and current is effectively due to the time it takes to charge each one up.

>>2619091
but i think improving power factor is effectively the same thing as a decoupling capacitor in a DC circuit. that's because the lag and lead of the voltage and current is effectively due to the time it takes to charge each one up. Yes, it will only be temporary due to changing sign of the AC wave but it's still enough time to provide a decoupling

>>2619536
Yes it free-run oscillates through R4.
The TL494 has a built-in oscillator. Hope you want it at that frequency.
I wouldn’t say it can’t act in a boost circuit. Usually the 723 wants 9v minimum.
That was just an app-note, it’s one of very many possibilities…this one being among the simplest to get designers started. For example, every 723 based regulator I saw also had at least one opto isolator.

>>2619558
>The TL494 has a built-in oscillator. Hope you want it at that frequency.
Well the frequency is whatever you set it via the R and C pins. Can't innately do variable frequency (e.g. PPM, current-mode) switching, but it's still very flexible. You could probably still bodge it into a current-mode or PPM circuit with enough surrounding componentry (e.g. a comparator feeding a transistor that pulls down the timing capacitor), but I'd wonder if it's worth it.

>I wouldn’t say it can’t act in a boost circuit. Usually the 723 wants 9v minimum.
Those statements have nothing to do with each other. A boost-style converter isn't one that's easy to make self oscillate like a buck-style, because the output voltage doesn't rise until after you turn the switch off. I imagine the more complicated circuits you've seen are self-oscillating buck-style isolated converters, the use of a transformer allows the voltage ratio to be decided arbitrarily. I can't find any reference to anything other than a buck-style regulator in appnotes either.

>>2619266
Well, yeah, if they're insulated, which most are..

>>2619261
Das brilliant; what's s buz among friends...

>>2619566
> boost, needs 9v min; have nothing to do with each other
I mean, as-is, that appnote circuit would be difficult to adapt to an inductive boost converter from a low Vin (say, 3.7v) because the 723 isn’t on yet.
Some LV energy harvesters use a free-running oscillator at the front end to boost the voltage enough for the rest of chip to function. This is not that.
> capacitative boost topologies are impossible
I think there are probably too many statements of random “facts” out there that can only be interpreted as true under a vanishingly small set of circumstances.
> most are buck converters
Yes, supplies for research and lab equipment, computer equipment. things that output high power. Boost converters are rare when it’s designed together since you get to pick your input voltage by means of transformer or by rectifying mains, and most things don’t need more than 200v to operate.

>>2619717
> free running front end
And here’s the (extreme example—20mV input) picrel
Note CW and C2, inside the chip, is basically a disconnected MOSFET, so the bulk of the work is actually done by the inductor/caps resonance and the MOSFET for amplification.

I think you could easily adapt some of these techniques for the 723. But doing it without any external components or thinking is going to be… difficult.

The 3108’s MOSFET is essentially an external component, it’s not really connected to the rest of the chip so you can replace it with your own with better specs, or use a different input boost topology using, say, germanium bjts, but you don’t need it to be built-in. This was my whole point with the 723.

Never been on this board before now somehow, but someone on /wsr/ referred me here, so maybe one of you can help.

I'm working on analyzing a circuit, and I think I might be missing something pretty obvious with the opamp and zener diode portions. I'm not really sure what that part of the circuit is accomplishing and what the point of the zener is if the Vcc is already regulated to 10V. I would say it's for overcurrent, but I think the node would have to tap off between D1 and R1 for that to make sense.

Anyone able to give some insight?

>>2619759
My guess would be that it dampens any induced voltages on the lines and/or emf from the relays.
Because it’s on a separate board.
Let me guess… it’s an unshielded ribbon cable that connects it, right?

Also, it looks like a bit of an afterthought.

>>2619759
diode clamper

>>2619760
Don't know. I was given this circuit drawing with no context or amplifying info. But I guess having some extra regulation in that case would make sense. If that's the case, would that first pin be another power source coming in?

>>2619767
I would say that it’s definitely not unusual to have
• multiple Vcc (and GND) pins
• have either of these as the first pin on the connector

>>2619761
Which part? I only see a capacitor on the inverting terminal of U1A. Is there another way to make a diode clamper work? Also, are you talking about the zener diode? Not seeing anything on google that shows a clamper using a zener diode.

>>2619771
That makes sense. So you think pin 1 could be Vcc as well then? I know it has to be DC for the Control Relay to operate.

>>2619772
Do you have a schematic for the other board that plugs into the header?

>>2619780
Nope. Only the drawing given. You have a guess about what it could be connected to or something?

>>2619794
DISCLAIMER: I'm a retard.

Now that's out of the way, It looks like a motor speed controller.

>>2619801
>motor speed controller
*speed regulator

Why are Automotive Ethernet (BASE-T1) interfaces so fucking expensive?

Anyone build one themselves?
Looking at LAN8770M-I/PRA at the moment.

>>2619805
Automotive electricals are very noisy.

>>2619801
>>2619803
Interesting. You thinking something like picrel?

>>2619776
Looking at that schematic again, that pin 1 could be the rectified, but unregulated output of the power supply. There’s no need to burden the expensive regulated Vcc with the extra load (and back emf/noise) of the relay coil.

That’s my best guess as to what that square Pin 1 is: unregulated “bulk” Vcc to power things that don’t really need great stability. Relay coils. Indicator lamps. Fans. Things of that nature.

>>2619808
Something like that. I think the circuit maintains a preset RPM within a certain range in either direction.

>>2619811
… also note that J2 and HDR1x16 would both have pin 1 as the same thing (unregulated psu input) Which would kind of make sense from a consistency point of view.
Probably the first thing the designer thought about: “need voltage” so that’s pin 1, LOL.

>>2619808
This is a “totem pole” configuration. That 3055 is like 10 or 15A transistor, so showing a motor that could be powered by a coin cell is kind of hilarious.

>>2619826
>is kind of hilarious.

not in the least.
that's the exact circuit for one of the decoys inside an Iskander missile (responsible for sales of blown-up parts of a Patriot anti-missile system being sold on the dark web today)

>>2619823
Yeah, I think that would make the most sense. Ground seems to be pin 3 on both, so power being the same pin would follow.

>>2619836
lmao does the motor power a gyroscope?

>>2619717
>inductive boost converter from a low Vin (say, 3.7v)
Nothing to say you can't boost from 12V up to 24V, though I get your point that it's probably not as common.
Also anything with a voltage ratio more than 2-5 or so will probably use a transformer-based converter so the point is kinda moot, since you can just change your turns ratio and use a buck-style converter (e.g. forward) instead. Still, a lot of converters in the 1-500W ballpark will definitely use flyback converters, which the 723 can't do. For example, the up-conversion stage in an inverter, and lots of step-down flybacks like you find in AC-to-DC SMPS devices.

>capacitative boost topologies are impossible
No I specifically meant "boost style" topologies, i.e. any converter with an inductive element that gets shorted between the rails by a switching element. So boost, inverted boost, and flyback.

>>2619749
Yeah there's definitely some specialised circuits out there that do things a lot better than the µA723 or the TL494. That kind of topology may well be possible to implement using the 723, though the quiescent current of it would kinda make it pointless for the very low power applications the LTC3108 is designed for.

>>2619759
I agree that it looks like the ability for it to run on two seperate power supplies, so if it loses power from J2 it can still run on the voltage rail that the PWM circuit runs on. Signal I/P looks like it will probably be a triangle wave, but maybe just an analogue voltage.

>>2619836
Is the whole circuit out there somewhere?

>>2619845
>two seperate power supplies
Would they have turbine generators or alternators in them with a battery for redundancy?

>>2619760
I'm actually wondering about this zener again. If the input voltage is 12-35VDC, which I think it is based on the P/S voltage at the bottom, then the zener diode wouldn't even be able to regulate since it's breakdown is 10V. Right?

>>2619852
More in case one wire breaks.

Chink LEDs should arrive this week.
How do I measure CRI with common hand tools?

>>2619877
make a spectrometer with a webcam and a cd or prism

>>2619892
Assume I have a spectrometer. These are three spectrums I got. Now what. How do I calculate if white point is on point of black body source? Or various CRI shits?
I know there is an aliexpress special device (OPPLE something) that uses ams-osram sensor with photodiodes and color filters and smarts and shit and it can measure CRI just for $40 in end device.... But idk why do I need it it. Especially since I'm not buying LEDs from store ever again. Luxmeter? All phones have luxmeter these days. Flicker? I trust SPICE simulation and simple calculations when it comes to flicker.

Is there a program that will calculate d U, V and idk what else, based on spectrum input?

Is there a decent board from aliexpress that doesn't loose the copper points like it's paper?

>>2619876
> thinking about zener diode
You’d think it would be closer to 12, possibly with ripple. You could figure out that upper limit on the psu voltage using the wattage of D1 and that 1.2kΩ resistor, R1.

>>2619862
> thinking about zener diode
You’d think it would be closer to 12, possibly with ripple. You could figure out that upper limit on the psu voltage using the wattage of D1 and that 1.2kΩ resistor, R1.

>>2619916
Yes, search for FR4 board. They are green and made out of copper clad FR4 which doesn't delaminate as easily.
Fecal-matter colored boards are made out of bakelite or paper bound phenolic resin or idk, fecal matter in general as copper delaminates easily from it.

>>2619920
Oh, i meant with the holes already made and stuff, i can't remeber the common name, like with isolated points.

>>2619921
Those are “pads”

>>2619922
Like this but not shitty

I'm working on a project and this thing doesn't grab any solder.

>>2619919
D1 is rated to 1W max. Don't have any additional info on the resistor though, so that doesn't really help. The Vz on it is 10V though, so I suppose the max current through that would be 0.1A, so I could figure max voltage using current through the resistor that way.

>>2619836
> iskander missles use a tiny motor used for children’s toys
I doubt that. Maybe the russian clone does.

>>2619921
Prototype board.
>>2619923
>doesnt take solder
Give them a quick sand with fine sandpaper (or maybe even scotchbrite pad).
Do you even understand how soldering works? Flux cleans ups oxide from layer, tin in solder forms an alloy with copper (i.e. wet copper).... Really doesn't matter, copper pipe or PCB, soldering is about cleanliness and temperature control.
Which is why you shouldn't put solder on tip and bring it to soldering place, as flux inside the solder just boils off before you bring it to the board.

>>2619942
I know how soldering works, it's really the board, some copper rings just come off easily. I'm setting the temperature of the iron to 310ºC tho.

I have ones that are better built but they're double sided and i don't know how to use those, either for single sided use or not.

>>2619944
Yes, they are of shit quality, so you have to be very careful with pressure and time you solder. Use leaded solder too, because lead-free requires 30C higher temperature and this makes soldering those bakelite fecal matter boards impossible... They are really deprecated technology at this point, nothing except knock off USB chargers use bakelite PCB material.
>I have ones that are better built but they're double sided and i don't know how to use those, either for single sided use or not.
Exactly the same way, except now you can route shit on two sides.
Also, pro-tip: copper is cheaper than solder, so quit making soldering bridges on protoboards, just cut copper wire and use it as a track.

>>2619908
Calibrate against the sun or a halogen lamp. There is spectrometer software out there, have a look at what youtube guys use.

>>2619945
>Also, pro-tip: copper is cheaper than solder, so quit making soldering bridges on protoboards, just cut copper wire and use it as a track.

That's how i've been doing all the time, i also find it easier and safer.

I can't use the double sided ones tho, solder always ends up going to the other side.

>>2619954
I'm pretty sure that some sort of shitty light source like monochrome LED or some gas discharge neon indicator would be a better choice for calibration.
Problem is following. Those three are LED with CRI 70, CRI 90 and halogen/incandescent. How do I calculate that?
>>2619957
This is normal, solder is supposed to wick hole completely. It wont short anything.

>>2619958
Ok, nvm, found out how:
https://www.lisungroup.com/news/technology-news/the-principle-and-basic-calculation-of-cri.html
Fuck that though. I came here to become degenerate, not do calculus in my spare time.
https://www.waveformlighting.com/tech/color-rendering-index-calculator
There is a calculator for it. So maybe I can make something like diodegonewild, where he took CD and webcam, but I think I'd rather get a diffraction grating or gay ray causing prism.

>>2619845
> 723 can’t do.
Of course, the 723 is a regulator. You’ve started talking about boost/flyback converters for some reason.
The TL494 has a whole 20-transistor 5v regulator built into it just so it can power all it’s other junk. Getting pedantic, it is not, itself, a regulator, and not a precision one, if it were. There’s also no appnote on the TL494 to make a 100W Class D amplifier with ≤ .01% THD so it’s therefore impossible?

In addition to the whole regulator, it’s got a bunch of other junk in there that is connected in inflexible ways and unnecessary for anything but those picrel chinese appnote boards.

Proving my point, there’s a lot of crap that people throw into parts for specific applications that are unused and unnecessary. I do this as a hobby, I’m not ordering regulator chips in 1M quantities where minimum parts count is paramount. I can wind my own inductors. Or, if it’s a toroid, get some other poor bastard to do it.

I’m sure the zoomers entering this field are working on microcontroller based voltage regulators written in python. (I think that was a joke, if they actually are, I don’t want to know)

I'm about to make my own molex to sata power adapter. wish me luck

>>2619974
Good luck with your hard drive igniter, Anon.
>Molex to SATA, wipe all your data.

>>2619974
>molex to sata power adapter.

dont forget to join the yellow and orange on the sata side for full-speed operation.

>>2619968
I get where you're coming from, we're basically comparing apples to oranges. I just see the 723 as inferior to the 494 for any kind of switching applications, like it feels its ability to be a switching converter comes as an afterthought. The current regulation also looks rather imprecise, relying on a Vbe. If you want to make the 494 precise, you just need to use a precise external reference, maybe use external error amplifiers too but I'm pretty sure the included ones are fine. Its ability for push-pull operation of a transformer are particularly useful for high-power isolated converters, and it can do a lot of different topologies.

>The TL494 has a whole 20-transistor 5v regulator
Isn't that a reference, not a regulator? It's not a brilliant one, but perfectly usable for a lot of cases. If you want precision, again you'd use an external reference. Like maybe a µA723.

>it’s got a bunch of other junk in there that is connected in inflexible ways
I don't see that at all, they're highly flexible. You've got two error amplifiers connected via diodes, which is perfect for making a CC/CV PSU or for including other regulating factors like temperature. It has adjustable dead-time, which is a useful feature for basically every switching converter out there if you're not using an external gate driver with its own dead-time. It has undervoltage protection, a PWM comparator, nothing wrong here. You could even coopt the PWM comparator by feeding a signal into pin 5. You have the option of either push-pull or single-ended. The only problem I have is the BJT output stage, but since discovering the active pullup (https://www.circuitden.com/blog/11)) to get a nice push-pull output out of it for a FET gate I don't really care anymore.

>I’m sure the zoomers entering this field are working on microcontroller based voltage regulators written in python.
Not even as a joke man, micropython is spreading due to the pico. Which is a shame because the 2040 is a really nice chip.

>>2620045
> reference not regulator?
The actual TL494’s reference core (minus the amp) is circled in picrel. It’s obviously a “5A” Brokaw bandgap reference that was not invented by the time the μΑ723 was already in production. The rest is a simplified op-amp and regulator-proper.
The TI intern that cribbed this circuit from the designer’s eng notes did a shitty job on the circuit and on the nearly non-existent theory of operation.

i want to build an ultrasonic transducer driver for a DIY ultrasonic cleaner. i've seen the commercial (chinkshit) brand ultrasonic drivers on ebay, which apparently use a royer oscillator type circuit and are fragile/blow up without much notice.

my thought is to instead hand wind a transformer with something like a 1:10 turns ratio. input is +30V DC being switch in a half bridge configuration, from my lab power supply.

half bridge will be switched at 50% PWM duty cycle via an MCU. the control loop will be a primary side current sense op amp, where the MCU does filtering and runs a control loop in software to modulate the PWM frequency such that primary side current sense is at a maximum (i.e. the ultrasonic transducer is at its resonance.) i have an stm32g series nucleo board which as a high resolution PWM peripheral so hopefully this will be enough to hit resonance.

should this work or am i over-simplifying things? an mcu is more expensive than a royer oscillator but it definitely seems simpler and less prone to blowing up than the chinkshit royer oscillators.

>>2620094
oh and i've also read about people recommending that it might be wiser to boost (via flyback) the input voltage to the 200-300V working voltage, and then H-bridge switch this into the transducer. i've thought about this as well, but getting the flyback stable with such a weird load might be a pain in the ass.

>>2620095

>>2620095
and this

>>2619987
>>2619978
it was easy. I had some spare modular cables and I hacked them together. two layers of insulation and it's all good. this was my reference

>>2620098
not very familiar with the tl494 but that doesn't seem like it allow for frequency modulation, at least not easily?

>>2620108
>frequency modulation
Transducer response is limited to a specific frequency range. Trying to modulate a 40kHz transducer will ruin it. That's why you modulate the pulse width. The circuit I posted is a sound projection amp. Point the array at someone's head and they can hear the PWM audio. Point it away and they can't hear it anymore.

>>2620114
>Transducer response is limited to a specific frequency range.

i think it's a bit different with ultrasonic transducers in my particular application, because resonance changes with mechanical load: what solvent, how much solvent, weight of the objects being cleaned, geometry of the container and object being cleaned, etc. that's why i need a control loop that finds and tracks the resonance point.

>>2620115
>resonance point
That's gonna be a chore if you have multiple transducers.

>>2620125
resonance will be ~40khz. i have an stm32g474 nucleo board that clocks 170 mhz and has 184 picosecond timer resolution. i think the MCU should have enough processing power to run several control loops at once.

>>2620130
Combining 40kHz and 80kHz transducers would probably be the least hassle to achieve the desired effect.

>>2618620
Regarding resisters labeled 1 and 2.

I was told one is 10K and the other is 15K but the color of the bands is so faint I can't figure that out. Any help would be appreciated.

>>2620185
You need a multimeter, dude. Just bite the bullet and get the cheapest piece of shit imaginable if you're pinching pennies.

Are op-amps just magic?

>>2620194
>Are op-amps just magic?

all electronics is based on magic.
take a piece of wire, wrap it around a pencil, and it acquires magic properties of inductance, magnetism, and resonance.
make a sandwich of a sheet of paper surrounded by two sheets of aluminum foil, and it acquires magic properties of capacitance, and holding a charge.

>>2619041
>why does only china make plug-in capacitors for your home?
For the same reason they make all sorts of fake rip-off crap. To screw folks out of money.

>>2620191
>You need a multimeter, dude. Just bite the bullet and get the cheapest piece of shit imaginable if you're pinching pennies.

Mine are blown they're crispy critter, this is a photo of somebody else's unit and that was a good idea thank you.

What mine look like.

I do have a multi meter.

>>2620194
No they're just op and will be nerfed in the next update.

>>2620200
I suppose your comment was tongue in cheek, but even if it was it's just as stupid as saying that magic makes us stick to the ground instead of floating away.

Nobody understands "exactly" how anything works. We have models and equations that work under certain conditions, and nobody with a clue uses the word magic. You're probably one of those cutesy shits who thinks "automagically" is an adorable term.

>>2620213
>nooooo you can't have fun you must be serious all the time
>and nobody with a clue uses the word magic
Then why do we get to have books like
>High Speed Signal Propagation: Advanced Black Magic
It's not only magic, it's advanced black magic. Or take any unix/lisp book from back in the day:
>We are about to study the idea of a computational process. Computational processes are abstract beings that inhabit computers. As they evolve, processes manipulate other abstract things called data. The evolution of a process is directed by a pattern of rules called a program. People create programs to direct processes. In effect, we conjure the spirits of the computer with our spells.
Instead of being a stuck up formal soulless industrial grade snobby cuck try being creative for once.
>I suppose your comment was tongue in cheek, quite indeed I've noticed your uncultured and ignorant approach to engineering methods which do not sit well with me as a distinguished member of royal engineering society which is a very serious institution indeed. Now if you'll excuse me I'll go back to enjoying my lovely tea with delightfully creamy semen infusion spread all over my soggy fucking crumpets. Pip-pip, cheerio!

>>2620210
I have a question about watts.

If I wire two 3000 ohm in series to make 6000 ohm, is that 2 watts if they were 1 watt each?

>>2620094
> royer oscillator is fragile
I don’t think you can make general statements like that, perhaps the chinese implementations cut corners like they do in led bulbs—like run everything at maximum rating continuously.

I probably wouldn’t start with a microcontroller, I’d just set up a vco and use your variable lab power supply to dial-in the frequency so you get a feel for the actual freq/power curve under different conditions/solvents.

Btw, i opened up a gfci the other day and there is a sweet current transformer in there (and a comparator to sense and trip) if you had one lying around so you could measure the current.

>>2620200
Because they don’t have central air, and there is thousands of small-ish individual inductive motors on a single building. In that scenario, they actually work and are useful.

>>2620114
I looked up “soundlaser” on google, and now I’m probably on another watchlist.
I’ll wait for styropyro to test one on himself first before building snything.

>>2620283

>>2620285
>watchlist
Don't worry too much, Anon. It's a very, very long list and getting longer everyday.

>>2620262
Yes.
If you add two 1 watt resistors in either series or parallel, the overall power rating will be 2 watts.

>Need to make an EMI shield for a board I designed (will be made from sheet metal folded into shape)
>I'm great at geometry and trig but I'm not a mechanical engineer so unfamiliar with CAD software.
>Draw my design by hand
>Throw it together in tinkercad cause I'm a retard (as a 3D model in it's folded state)
>Export as a step file and get onto a few fabricators
>Get told to fuck off, they want a PDF of the part
>Download freecad
>Mad amounts of rigmarole just to place lines and rectangles around specific X and Y coordinated
>Download Solid edge
>Same shit but I stick with it and make my part as a flattened model to be cut from sheet metal
>Try to draught it
>Can't get it to scale to a size that's actually fucking visible on a page
>Go on youtube to look at solid edge tutorials
>All pajeets with undecipherable accents standing 10 metres from their microphone with constant car horns and shanty town noises in the background.

Someone recommend me some software or a fucking tutorial to draught this shit

pic related is the model in tinkercad

>>2620300
Lol, non-pcbs…
They haven’t for decades now.
Might as well put “no sugar added” or “vegan” or “kosher” on that cap too as equally valid selling points.

>>2620338
They probably get a tax break for putting it on the label. Not joking.

>>2620327
cut squares out of copper or mu metal nerd, wft is this shit

>>2620327
The probably wanted the dimensions on there.

>>2620340
You can tell a retard did it because the used the possessive form when they needed the plural.
The non pcb’s what?

>>2620363
Imagine working for Heartland Controls as a data entry clerk. Maybe they make the jannies do it for free.

>>2620185
Can't see how a 5=green could be in there, I only see black, brown, and red in there.
Looks like:
>red,red,black,brown,red
>2201 = 2.2k 2%
and:
>red,black,black,brown,red
>2001 = 2k 2%
It's possible that the colours are really muted, maybe the two browns are actually other colours (they do look different to one another) and some/all of the reds are actually browns?

>>2620327
Can't you just design it flat in 2D CAD like inkscape or Qcad, to bend yourself? They can export SVG, PDF, and postscript IIRC.

>>2620338
>They haven’t for decades now.
china is stuck 50 years in the past

I'll try to run a 3-phase HDD motor on BJTs, can't imagine it needing sine waves for a low torque application (fan).
A simple ring oscillator and that should be it, in my mind. Can't stand making an order for a crappy H-bridge or few mosfets for <12v...

Prime retard here.

Is the TO-220AB package standardized? How the hell do I tell the pinout from the datasheet?

Particularly on this: https://www.infineon.com/dgdl/irgs14c40lpbf.pdf?fileId=5546d462533600a40153565a8ec424b1

Yes I know I'm retarded, You don't need to reiterate this for me.

Thanks frens.

>>2620533
page 10 of the data sheet has the pin out in the right margin, with the pin numbers on the top left drawing of page 10 as well. kind of stupid of them to bury it there.

>>2620535
Thanks guy. Had to actually zoom in to even read that.

>>2620447
You still need totem-pole outputs. Three different phases will be kinda janky but should work and be easy to make, but you should add a slow start circuit to your oscillator so it begins at a lower frequency. I think a big capacitor on the CV pin of a 555 will do that. Post circuit.

>>2620540
The fact that there still lots of data sheets without obviously defined pinouts is a fucking travesty. It should be written on the first page, not at the very end on with the package dimensions.

>>2620571
>It should be written on the first page

maybe they want you to read the whole thing.
nobody does that otherwise.
certainly not me.

>>2620316
>Yes.
>If you add two 1 watt resistors in either series or parallel, the overall power rating will be 2 watts.

Thank you.

>>2620635
Note that this only happens when the resistors are the same resistance. If you put a 1k in series with a 9k, then only 10% of the power will get dissipated by the 1k, the remaining 90% will get dissipated by the 9k. Conversely, if you put 2k in parallel with 6k, the 2k will dissipate 3 times more power than the 6k.

I bought chinkshit flux for a dollar off ebay, but it's all solid. Do I just stick my soldering iron in & get it to melt?

>>2620690
If it's too hard to scoop up with a spreading stick, then yeah.
Might wanna buy flux that's not a total pain to use or you'll never run out of this stuff.

>>2620385
>Qcad

Cheers our lad

>>2620707
>Qcad
Trust the plans.

>>2620690
Heat it up a little and mix it with some isopropyl alcohol.

>>2620690
Yes. It is pure rosin. This is the only type of flux you bring on soldering tip to joint.
Also you can crush it and mix with alc.

>>2618620
One of the windings on my transformer has 10k resistance, which was measured after desoldering the entire thing from the board to test it. Why?


An audio tranformer I have has three primary windings. Or Two if the high resistance one is actually a secondary, since I see two wires going from the some of the 'primary' pins to the second coil.

Pic related is the transformer, but the schematic does not show the two high resistance legs that are on the 'primary' side.

The circuit it is connected to also doesn't show up on the schematic, where in it looks like it controls the UVP for the switching IC via a diode from mains, a zener and a pair of transistors. UVP is already comes from a voltage divider like the OVP, but this circuit some how alters it.

>>2620750
Also the board does not link the UVP to the VCC via a 27k resistor, like in the schematic. The 27k is not there and they are not connected. So question is what is the purpose of these two legs having such a high resistance? What is the purpose of it?

>>2620094
>stm32g
Bro, just get a switching IC.

>>2620753
>>2620094
Like why are you using embedded coding to handle the feedback loop, when switching ICs already do that for you.

You should can use the MCU for the secondary side. When you want to control the output power, but you need to generate voltage in order to control the power, like an audio amplifier.

>>2620095
If using 30V input is something you are not willing to change for your design, then disregard this part.

>to the 200-300V working voltage
Why not use mains for that then? People regularly rectify 120 VAC to 340 DC for smps using 2 (4 in practice) capacitors in series from 170V to -170V with the neutral connected where they meat in series.

>>2620707
Nice.
If it were me, though, I’d design the RF section to fit into an obtainium deluxe solder frame with snap on cover shield and save myself a lot of grief.

Anyone have a good stepper-motor selection site or chart? I need something of small size but high holding torque, preferably over 80oz-in. Unfortunately these seem to be contradictory requirements. I have only been able to find looooooong NEMA17 motors, else have to move up in size.

Is there such a thing as a locking stepper, where when it's not actually moving, something physically captures the rotor so that it can't move?

I was thinking of using lead-free solder to tin stranded wires that I intend to screw into terminal blocks, because tin-silver-copper are all harder than lead which is 40% of leaded solder. Anyone think this is a good idea? For the rest of the time I'm using the 63/37 tin/lead no-clean solder I already bought.

https://en.wikipedia.org/wiki/Solder
>Composition
>Lead-based

>Tin-lead (Sn-Pb) solders, also called soft solders, are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder's tensile and shear strengths.

>>2620800
It's better to crimp ferrules onto the wires for use in terminal blocks.

I was thinking of using lead-free solder to tin stranded wires that I want to screw into terminal blocks, because tin and silver and copper are all harder than lead which is 40% of lead solder. Anyone think this is a good idea? For the rest of the time I'm using the 63/37 tin/lead no-clean solder I already bought.

https://en.wikipedia.org/wiki/Solder
>Composition
>Lead-based

>Tin-lead (Sn-Pb) solders, also called soft solders, are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder's tensile and shear strengths.

>>2620801
Ahh, yea, deleted post, thanks though

>>2620800
>intend to screw into terminal blocks

in that situation, you dont want hard, you want soft.
so it gets squeezed flat and increases area of contact.
and decreases resistance.

>>2620805
Problem is lead is so soft that I thought it might deform over time to the point that it's loose?

>>2620824
Better to deform than crack and break.

>>2620781
That would be the obvious and easy thing to do but I've a load of these fuckers passing through the shield that I need cutouts for

>>2620647
>Note that this only happens when the resistors are the same resistance. If you put a 1k in series with a 9k, then only 10% of the power will get dissipated by the 1k, the remaining 90% will get dissipated by the 9k. Conversely, if you put 2k in parallel with 6k, the 2k will dissipate 3 times more power than the 6k.

Oh, I didn't know that, thank you.

>>2620802
>I was thinking of using lead-free solder to tin stranded wires
Do not tin stranded wires, they will break at place where you've tinned them. There is a reason why ferrule exists.
>lead-free vs leaded
they are more-less the same, leaded is more ductile, lead-free is harder. If you're interested in specific MPa and other shit like idk yield modulus, check specific alloys. Like idk, 63/37 vs SAC305 vs SAC0307 etc
>>2620801
This

I'm planing to do electrics of my new house by myself. Is it possible to somehow fuck it up royally? Cause I ain't going to pay tens of thousands of my precious euros for this shit.

>>2620886
Electrics is not about electronics, but following local codes, we can't know them. But generally 2.5 mm^2 for sockets at 16A B/C breaker, and 1.5mm^2 and 10A breaker for lights. In UK it is weird ring.

>>2620756
>switching ICs
what does the control loop look like (in analog hardware) for finding and tracking resonance? it's software it's easy.
>Why not use mains for that then?
i dont trust myself to work with mains. building a dc-dc boost or isolated flyback converter is comparatively safer.

>>2620866
> they will break at place where you've tinned them. There is a reason why ferrule exists
Yeah, they totally won’t ever break at the end of the ferrule.
This recent ferrule advice comes from people that measure the capabilities of their soldering iron in MHz and MB/s and have never had to repair anything in their lives, and don’t care to learn.

>>2620866
>>2620929
You shouldn't tin wires if they're going into crimps or screw terminals ever.

t - Retard that got IPC training a few years back

>>2620929
>Yeah, they totally won’t ever break at the end of the ferrule.
It won't. Because it doesn't create a stress point, unlike tinning/soldering. Which is the reason why in vibration-prone environments cables are usually crimped, not soldered.
It is pretty easy to confirm the shit im saying, grab a ferrule, crimp it. Grab other cable, tin it. Start bending at the ferrule/solder. You will realize pretty fast that tinned part would just break off. And ferrule won't.

In real world, if solder joint is required on a stranded cable, let's say laptop charger connector, they solder it, and then cast it in plastic so shit doesn't move at solder joint.
>Soldering iron in MHz
My smoldering iron is controlled by an op-amp :D
>>2620936
Europoor terminal block things are disgusting as screw cuts strands off the wire. So I'd put some sort of ferrule there... Acually I'd throw away that piece of shit and use WAGO or wire nut.
Proper terminals (like on circuit breakers, or even shitty $1 per 100 PCB mount connectors) are much better designed and dont have this problem at all.

I need to detect a >5v or so voltage betwen two points and not draw any current from it more than maybe max 100 uA or so, and give some signal to an MCU if the voltage is present. The circuit producing the voltage is also not connected to the sensing circuit ground. Is there some simpler way of detecting this differential voltage other than using an instrument amplifier?

>>2620988

a logic-level mosfet (i.e. turned on by 3V or more) will detect a voltage while sipping only pico amps.

>>2620936
> don’t tin crimps or screw terminals.
I actually agree, but it’s not a huge problem, and I do it all the time. Lots of UL listed products (lights, appliances, etc.) have tinned stranded wire going to terminals and/or tied into twist nuts.

If it’s a crimp, sometimes I solder it AFTER it’s crimped. The mechanical connection will stand by itself already.

>>2620982
> moulded PVC
You’ve never had teenage kids have you. I’ve had to repair multiple dozens of headphone, USB and Lightning cables. They always fail right after the PVC or silicone moulded strain relief.

Any discontinuity in the stiffness is going to be prone to breaking.

I assume you mean ferrules with those strain relief… they are functionally identical to tinning with heat shrink.
When I tin a wire, the tinning usually goes about 1/8" under the insulation, and the insulation itself acts as a strain relief. It’s probably not as good as heat shrink, and definitely not as good as a tapered gradually thinning PVC overmolding, but neither is the ferrule.

>>2621045
> simple voltage detector
Assuming that’s a 20mA LED, this circuit will only work between zero and one time (briefly).
If you didn’t burn through the gate insulator in the transistor by touching the “antenna” then the worst case current it could put through that LED is around 67mA. Into a 20mA LED.
This is how Philips rates their components in their light bulbs.
But seriously, I do love me a good indian-designed electronics schematic.

If I have a regulated +/- 20V supply and I need to lower it for a TL072 opamp, can I get away with just a 3/4 voltage divider or do I need to make something with zener diodes? What's the simplest/easiest way here?

>>2621082
Either is fine for an op amp. Low current. You need 1 resistor in the zener diode case anyway. Make it (or them) a high-ish value.

>>2621052
>Lots of UL listed products (lights, appliances, etc.) have tinned stranded wire going to terminals and/or tied into twist nuts.
I meant tinned like with soldering iron which forms a solder blob that joins copper conductors. Electroplating or chemical plating of copper is obviously fine and is actually good as it resists corrosion.
>You’ve never had teenage kids have you. I’ve had to repair multiple dozens of headphone, USB and Lightning cables. They always fail right after the PVC or silicone moulded strain relief.
I didn't but I've repaired cables. I think it breaks right after solid plastic.
>Any discontinuity in the stiffness is going to be prone to breaking.
Yes. This is what I wanted to say, but for some reason (probably severe brain damage form lead) didn't think of.
>I assume you mean ferrules with those strain relief… they are functionally identical to tinning with heat shrink.
I'd say crimped ferrule, even without plastic thingy on the end, doesn't cause as much stiffness difference as solder. Like transition from stiff to not stiff is wider.

Idk, most of my experience with vibrating shit comes from e-scooter. Engineers at Ninebot decided to use something that looks like dupont connector for signal cables, but in reality it is not a connector but a weird thing that accepts crimp on one side, and solid metal on other side. Kinda like male dupont crimp, but soldered to PCB.
This shit lasts. But when I did solder shit directly to PCB it always broke off where solder wicked under insulation.

But then again, what is the usecase? If it is stationary shit, it doesnt really matter what so ever.
CNC, e-scooter, car, idk airplane? I'd want to see a crimp, or some other restraint, even a blob of hot snot would do.

>>2620750
I’m guessing it’s a thermistor tucked inside the transformer windings. See if its resistance changes when you heat it up.

>>2620753
It needs to be variable frequency resonance seeking. While circuits made of latches and comparators like on a current-mode controller could be made to work, a microcontroller is both more than fast enough and adds the capability to adjust the phase offset or to class-D a lower amplitude output for different power settings. Since he probably needs a microcontroller to handle timing and UI, there’s no reason not to also use it for producing a driving waveform.

>>2620796
Might be better off with a gearbox on your stepper, or a BLDC (probably also with a gearbox). You may find that it’s necessary to measure displacement using an encoder, and actively driving the stepper with a higher current momentarily in order to avoid skipping steps. If you use a BLDC this feedback is a requirement anyhow.

>>2620866
>mfw creality 3D printers tin their stranded wires

>>2621082
I’d use a couple of zeners, they’ll give you a few dB of PSRR.

>>2621065
>But seriously, I do love me a good indian-designed electronics schematic.

the text tells you how to do it.
the drawing illustrates that even a small gang of electrons flowing through the air can trigger a fet.
it is an explanatory drawing, not an actionable one.
being overly literal is a possible sign of being ''on the spectrum''.

>>2621144
Are you spectrum shaming? Did you assume his spectrum? Is "A" in the LBGTQanon spectrum? What color is it in nm and Kelvin?

>>2621082
>+/- 20V supply and I need to lower it

one (possibly non-intuitive) way to use zeners is this.

>>2621151
makes sense. I think I have some 4.7V 1W zeners laying around. might have to try it

Trying to setup a nanoscale motor system. From my research it looks like the best options are either to go with a unimorph disk or with a piezotube. For the unimorph disk I have to take care to split it in segments myself because nobody actually manufactures them for that purpose, but I'm concerned that inexact cuts will impact the nm <-> volt calculation for each segment and thus make the calibration more of a pain. On the other hand it's a simpler design with more material on it than the piezotube. For the piezotube it's electrodes layered inside and outside the tube with differential current causing the movement. The overall diagram looks kinda like pic related. Tip will probably be Pt-Ir, but I'm also open to suggestions.
Also will probably convert to using a motion sensor on the module above the tip instead of tunneling for detection.

>>2621206
And here's the control circuit

>>2621208
Oops, meant this one. That was the preamp schematic.

>>2621208
I don't suppose it matters much but why'd you make it inverting?

>>2621206
For precise cuts in the top electrode of a piezo disc, consider using a laser cutter and/or masking it off for etching. The "and" method is using a laser cutter to burn away an etch resist.

I don't know what the hell you're describing though, sounds similar to an atomic force microscope but idk man. If you don't mind, elaborate on what this does and the particular requirements for your circuit.

>>2621256
Not him but that's a current-to-voltage converter, not an inverting amplifier. A non-inverting model would just be a buffer with a pull-down resistor at the start, and would lack the property that the needle is held at a constant 0V with respect to ground. Which is probably important in this kind of electrostatic circuit, idk. Inverting topologies are also generally more stable.
It's also an absurd circuit with a 100MΩ resistance there, but if he's doing that I can only guess he needs to do so. I'm somewhat worried about the lack of a capacitor in parallel with R1.

>>2621101
> usecase?
How about drones? Soldered Amass connectors.
How about the onewheel? Soldered Amass connectors.
Space shuttle? Yep. A lot of soldered connections.
Anyway, the crimp/ferrule thing is just a recent meme/fad like the pinecil, and using copper scouring pads to clean your iron, based on a bunch of old wives’ tales and some attempt to look like they have street cred.
> tinning means <some other thing that isn’t tinning>
Connecting wires with a blob of solder is just as triggering as the crimp is better than solder parroters. Maybe more triggering especially in self-described “tutorial” videos

What's the easiest way to set things up for embedded programming in Rust?
Yes I do hate myself

>>2621260
>I don't know what the hell you're describing though, sounds similar to an atomic force microscope but idk man. If you don't mind, elaborate on what this does and the particular requirements for your circuit.
The design I have here is for a scanning tunneling microscope, which is pretty easily converted to an atomic force microscope (it's the same hardware and control electronics, just you check movement of the cantilever by displacement instead of by tunneling voltage difference). Because the system is inherently imprecise due to using cheap parts on purpose, it is meant for constant height operation only.

>requirements
- Less than $1000 amortized total cost per unit
- Final device no larger than a typical desktop computer (the model I show can be prototype on the size of a hand, so far so good)
- As high an axial resolution as possible (I would love to get 0.1 angstrom, but that's not happening, SOTA instruments costing hundreds of thousands get around 1 angstrom though, and other cheap STMs and AFMs can get to 10 angstrom rather easily, surprisingly. I plan to use a mix of slightly better hardware and much better software to see if I can close the gap). I want to experiment with the limits of spacial sequencing. At 0.1 angstrom resolution, it would be possible to sequence peptide chains with only leucine/isoleucine being indistinguishable. At 1 angstrom you can call 14 out of the 20 usual AAs accurately. It might be possible to target specific proteins e.g. by suction (for example by replacing the tip by a nanopipette) and use structure information to close the identification gap. Might also be possible to play tricks like (again wit ha nanopipette) solid state nanopore sensing. tl;dr: I'm building an exploratory platform.

>For precise cuts in the top electrode of a piezo disc, consider using a laser cutter and/or masking it off for etching. The "and" method is using a laser cutter to burn away an etch resist.
Thanks anon, I'll look into that.

>>2621312
>using copper scouring pads to clean your iron
this is old shit, new shit is cleaning iron with fingers or toilet paper.
>How about drones? Soldered Amass connectors.
Used on thicker gauge wires. And I've seen shit break... exactly at transition between solder+copper and copper.
XT60 and all similar connectors suck ass, because there are too many chinkshit ones floating around that are made out of cardboard brass that break moment you look wrong at them.
>Space shuttle? Yep. A lot of soldered connections.
Yes, but there is a caveat. Every solder connection, even those "mom look I did mod my PS2" are restrained in one way or another, or is a short piece of wire connecting whatever to whatever, where wire wont move like at all in normal operation due to its small size. Other thing is it probably comes with a giant ass manual on how to solder, where they tell exactly what do.
>Connecting wires with a blob of solder is just as triggering as the crimp is better than solder parroters. Maybe more triggering especially in self-described “tutorial” videos
I wanted to distinguish between tin plated cable and soldered cable. Not shat together pajeet video joint with no flux.

And for those who likes to solder wires in vibration environment without restraint, i suggest new hobby of fixing flat flex cables at bend :D

>>2621383
I had no idea...
https://arxiv.org/ftp/arxiv/papers/2109/2109.10398.pdf

>>2621383
didn't mean to reply to your post
sorry

>>2621396
No,that was good, I forgot piezoelectric transducers have been soldered for decades for decades without issue. You don’t get a higher vibration environment than that.

>>2621312
I thought linesman splices were only used with solid core wire? Because in that case the rigidity difference from the joint compared to the wire isn't nearly so drastic.

>>2621602
Well even solder has some degree to which it can move elastically. If the vibrational displacement is only very small (10s of micrometers) then I doubt you'd have to worry about work-hardening of the solder or your wire. I'd look what wire connections they use to the piezo stacks as seen on ultrasonic cutters, cleaners, and emulsifiers.

>>2621620
> if you use linesman splice with stranded wire the world will end.
No.
> work hardening doubts
Work hardening happens at an atomic level, in this case sub-nm.
Look at those foil tests in the ultrasonic cleaners. It’s well-known that part of the effect is due to the embrittlement of the Al and the additional friability makes it more susceptible to destructive cavitation.

Hey lads, I'm sorry to be that guy, but I know fuck all about electronics and could use some help.

So I'm a train sperg and I make large scale (1:19.05) models, and run them. Some are steam and some are battery electric. The problem with battery is it can run out, can be a pain to change the batteries, that kind of thing, so I wanna make a brake coach (pic rel) and shove it full of 7.4v rechargeable batteries. I want to have a 3v output for the cables that will run the LEDs in the other coaches, and a 6v output for the power supply of the locomotive.

Locomotives tend to have their own batteries, but being able to hook up a power supply to the train that will last all day would be ideal. I tend to buy ready wired RC Kits (usually end up modifying and shortening things anyway) but they run on 6v, they likely would handle 7.4 but I'd like to standardise it.

Now, I know nothing about resistors. What kind of resistors and set-up would I need to step the voltage down from 7.4v to 6v (Max of 500mA) and 3v at low amperage?

I know all of this isn't necessary and I could just put AA batteries in the coaches, but I may end up doing that anyway with a switch that I can use to disengage the AAs and let the train be powered by the brake coach.

>>2621654
Use metal tracks and a speed controller.
https://www.amazon.com/Model-Train-Controller/s?k=Model+Train+Controller

>>2621649
The actual micrometre distance the piezo disc moves corresponds to a radius that each strand of the wire bends at, which corresponds to an elongation percentage at the outside of that bend, which itself corresponds to that nanometre scale deformation you're referring to. It's apples to oranges. If the resultant deformation of the strand isn't enough to push it into the plastic region, then it will just deform elastically and won't work harden.

>>2621654
>step the voltage down from 7.4v to 6v (Max of 500mA) and 3v at low amperage?

this is a lil inefficient but is easy enough for a noob.
each diode lowers voltage by 0.7V approx.
so use 2 in series to get 6V, and 6 in series to get 3V.
recommend using the 1N5401 (rated 100V, 3A) coz motors can have a high starting current.
note that diodes have a certain polarity.
google to match symbol with actual pic.
(if you can get at the 3.7V center tap then you just need 1 diode to lower it to 3V, increasing efficiency by a lot)

>>2621654
>3V for LEDs
Something tells me that there's no implied current limiting.

>>2618620
>Recommended Design/verification tools:
>KiCAD 6+
>Circuitmaker
>Logisim Evolution

Guys, will any of these help me verify if my project will work? I'm trying to make a 3D printed USB powered lantern with a strobing effect so it looks like a candle. What I was thinking is getting LED strips powering them via a phone charger with a USB cable with maybe a timer chip and capacitors/resistors/transistors or whatever else I need. I'm not sure, never done this. I'm retarded. I'm trying to fuck around with a million combinations in the program until it verifies it will work. What do you guys say? Am I on the right path?

>>2621658
The problem is, in the UK, SM32 scale is mostly controlled via battery. The reason for this is steam powered models, and rolling stock, often do not have isolated wheels, meaning the rails would short through the wheels. Additionally, as I want to take the rake or "Consist" to other garden railways, I cannot guarantee track power there, and only people who model in Gauge one or LGB type 45mm garden rail tend to use track power.

>>2621684
Thanks! That's genuinely very helpful. I'm not too inclined to to cut into the packs, so the voltage limiter is honestly a big help. (having the ability to swap battery packs in and out easily when one dies is important as I'll be using off the shelf packs, and this is honestly going to be a lot simpler than doing it on the locomotive models themselves)

>>2621689
>Am I on the right path?

you've chosen the hardest of all paths.
simplest path: buy it at the dollar store.
medium path: google a schematic for the thing you want, order parts, assemble on breadboard, dick around with it.

>>2621689
https://www.amazon.com/Round-Orange-Amber-Candle-Flicker/dp/B017TR8602

>>2621689
LTspice is the only simulator I'd really recommend, but even then it isn't going to be very good for your purpose. Look up a bunch of existing circuits (IIRC Big Clive took apart some flickery candle style LEDs) and try to make them on a breadboard.

The problem with simple oscillators is they'll be on or off. With enough LEDs of different brightnesses and/or colours running on different frequency oscillators (probably at least 5) it will probably look decent. On the other hand, if you want a single LED then you'll want something a bit more nuanced, such as:
>LFSR feeding a resistor ladder DAC with a buffered output
>summing the output of multiple triangle, sawtooth, or sine oscillators
>using a microcontroller to PWM the LED
A cheap and cost effective method is to have a small number of square oscillators, each with their own frequency and brightness, hooked up to a single LED (or LEDs in parallel), pic related.

If you want it to be brighter than a $20 headlamp from 2005, you'll probably want to use multiple LEDs.

>>2621696
>>2621699
>>2621700
I'm confused.

>>2621703
You've come to a fork in the road. Choose your path.

https://www.youtube.com/watch?v=r9LIGIOqUsI

Sirs, what about this?

>>2621678
> work hardening only happens in wire proportional to bend radius.
Tell that to machine shops and the people that are doing high frequency weld hardening. They’d probably disagree.

>>2621724
> circuit components connected with solder bridges and blobs
The poor guy only has one transistor, so he can quickly desolder it and make an audio amplifier out of it for the next video.
I usually use Motorola TO-3 3055s to drive my single LED flashers, driven by my latte panda SoC board running Windows 11 using Python 3.x

>>2621724
>reverse bias BJT oscillator
been a while since i've seen one of those
they'll work most of the time, assuming you want a strobe light instead of a candle

>>2621729
>I usually use Motorola TO-3 3055s to drive my single LED flashers, driven by my latte panda SoC board running Windows 11 using Python 3.x

Anon you're making fun of me.

>>2621730
What about the candle?

>>2621734
> fun of
That is you in the video?

Okay then.
A very effective and good looking candle effect can be achieved using an lm3915 in bar graph mode, and a few sine wave oscillators summed together as the input.

Are wood cardboard paper electrostatically safe materials? I imagined that because they are organic materials they would absorb some moisture from the air and thus have some trivial conductivity

>>2621809
Ever rub your wool-socks clad feet across your shag carpet in winter and touched something made of wood an received a shock? Me neither.

>>2621734
>What about the candle?
I already said: >>2621700

>>2621738
>sine
The pseudo-triangle waves from the RC node of a relaxation oscillator would be perfectly fine. You can add in an extra RC stage to such an oscillator and get a decent approximation of a sine. You could use a 74HC14 (or 4000 series equivalent for wider voltage range) to get 6 oscillators, using the same double RC filter for sine-ish waves. Having 6 different frequencies and different voltage dividers would give you a decent assortment of waves. Though if you're using a common inverting summing amplifier then the impedance drain on the RC node of your oscillators might prove to be an issue.

>>2621809
When soaked in mineral oil they're decent. 3D printed PLA is actually pretty great, since it's somewhat hydrophilic. If you use the white stuff, then the titanium white pigment gives it a higher permittivity in case you're making diy capacitors.

Can I make loads a money if I know how to fix electronics?

>>2621867
If you target certain demographics, maybe.

Computers will always be reasonably in demand, but they're so complicated it's basically an entirely different field. You barely do anything from electronics principles, rather you act from computer repair principles. Phone repair is the same, but even more extremely so.

Less dense consumer electronics like televisions and microwaves and the like are definitely more repairable, though the firmware side will be even more frustrating than with computers. Locked down bootloaders with no documentation will make any repair that isn't purely a matter of hardware a nightmare. Logic analyser recommended purely for reverse engineering.

HiFi and audiophile gear is the true gold market. Simple circuits made with large easy to solder components that are easy to troubleshoot, that people pay a fuckton of money for. But your local population density needs to be high enough to focus on these.

Dumb appliances like toasters and lamps and ovens will be basically trivial to troubleshoot and repair, but the presence of proprietary mechanical components may trip you up. For these you may need a stockpile of common parts to have decent turnaround times. Though for non-heated areas a 3D printer may do you well.

Power tools is another one that can probably be dead-simple to repair, but with form-fitting switch/trigger modules and specifically sized motor brushes you may have long turnarounds.

You can both advertise to people trying to get their dead electronics fixed, and buy dead electronics and sell them on after fixing them up. This latter method may be less frantic and maybe even more lucrative, considering you'll be able to upgrade old sound systems with bluetooth and add dimming functionality to lamps and such. Not to mention repainting or plating to match more modern aesthetics. Check your local scrapyards and junk shops. Wish I had a scrapyard like TPAI on youtube.

>>2621865
>I already said

I know anon but I didn't understand that. I think I'll just try messing around with an arduino instead.

>>2621891
Just google those keywords. You'll see that:
>a DAC is a way to turn a digital value into an analog value, resistor ladders in particular taking a parallel digital input
>an LFSR is a simple pseudo-random number generator with a parallel digital output
>PWM is a method for dimming an LED or other load
>a microcontroller is the thing on an arduino board
>a 555 astable is a simple oscillator
This is the kind of shit you should read into to help you get acquainted with electronics. A book in the OP isn't a bad idea. Otherwise you may end up settling for a design that just doesn't feel like a candle at all.

>>2621901
Anon can you make a youtube video guide? I can solder.

>>2621904
>jewtube
read books you zoomer

>>2621906
What book will have a step by step guide on the circuit I'm trying to achieve?

>>2621913
>What book

thing about books is they cost a lot of money to produce.
so you have to have a big audience.
of fags.
coz only fags read books.
web pages, on the other hand, cost pennies to make.
and are suitable for audiences as low as 3 people.
hackaday.com is one example among millions.
so, bing the thing you want.
something like this ''hackaday led candle''
or ''hackaday why does poop smell''
or whatever.

>>2621913
Ask Jeeves about ferrethandjobs.com

>>2621929
Hackaday is cool. Too bad I didn't find what I was looking for.

Found picrelated on the sidewalk. Turned it on and the backlight is fucked, with only two strips of 10 working. TN panel works fine. Researched online and it looks that the LED driver overvolts the strips during startup. If I change out the strips and regulate the voltage on the driver output, will it work reliably?

inb4 >Vizio TVs suck ass
I don't really care since it's free. As long that I spend up to $200 for a few years of service.

>>2622095
Mod it to use an external power brick (remove the internal PSU) so it runs cooler. Replace all of the LED strips and use a generic LED driver for each strip so you can replace them cheaply and easily in the future.

>>2622100
You seem to know a bit about these tvs. I hope that the LED driver doesn't use i2c or other serial protocols.

why the fuck did they interleave the segment and grid pins

>>2621725
In ten minutes time I am going to post "Adele is fat". I'm just giving some warning and advance notice so a crowd has time to gather.

>>2622248
some sort of /diy/ /mu/ crossposting?

>>2622233
Well this arbitrary wiring won't make the software complicated at all.

>>2622233
They’re making a cheap 4-5 GHz filter with pcb trace inductors and capacitors?

>>2622332
ah of course, using the vfd as an rf amplifier tube, i should have seen this coming

Hello,yes. What paste is recommended to use for alu/alu and alu/copper conduit connections in wago connector. Also can i/should i use it for terminal blocks;if so how to apply? just dip it into the paste and good to go? Any particular brands? Noalux seems to be pretty good for this.

tfw just got some free industrial surplus
bunch of big 12.5 kvar 480v caps in it plus big breakers and stuff.

Going to sleep now, but someone tell me if they can see anything wrong with this method of driving a VFD.

I'm using UDN6118As for both grids and segments, which I'm pretty sure is fine.
More experimentally, I'm making out-of-phase ~40kHz 5V square waves, feeding them through an L293D, through some DC-blocking caps, and into the filament with only a pair of small resistors for regulation. Then I've built a clamp circuit with D1, D2, and Q2 that should keep the highest point of the square wave below a set-point. This should allow me to adjust the mid-point of the square wave (and hence the bias voltage of the filament) to anywhere between -4 and +8. I suspect a voltage of about +1V to +2V will be optimal, so I have plenty of room for it.

Actually looking closer, the typical total dropout of the L293D is 2.6V, so I'll be underpowering my filament. I'll work on duplicating the Q1/R4 circuit for the L293D.
>inb4 LM317
Too much dropout. I have some AMS1117-adj chips lying about, but since one of my 3.3V ones died I can't trust any of them.

>>2622370
John's gonna be pissed.

>>2618620
I enjoyed making microcontroller and IoT based projects a lot when I was just getting started but ever since I started making a lot more electrical heavy projects (more inductors, switching stuff, opamps, etc) I don't enjoy it anymore. Don't get me wrong, I always liked the engineering process, but with the newer projects I spend tons of time just designing stuff and running sims or calculating stuff in excel
Anyone experienced this? I also got employed as a firmware dev but I don't think that's related

you guys ever use +/-15V?

>>2622517
>ever use +/-15V?

that's every op-amp circuit ever made.
every piece of audio gear, too.

>>2622095
Pretty much, but also you might want to lower the brightness.

>>2622502
yeah. soldering and debugging are a bitch, especially when you have no comfy space for them.

>>2622412
Pretty sure John is dead unfortunately, from the stories I remember.

>>2622620
RIP, John. His blue box will live on in our hearts.

I have developed a novel product that fills an unoccupied niche that will definitely sell well
how can I prevent it from being copied by china for as long as possible

>>2622370
a little glimpse of the inside
>>2622646
RIP

>>2622651
It actually looks pretty good. What are you gonna use it for? You got moonraker laser beams?

>>2622648
why prevent free advertising?

>>2622648
If it's a physical product (including an electronic device), just the mix of support x implied quality control is enough so long as your price is right. For all intents and purposes, in this state, chink shit actually fills a different niche from yours.

>>2622648
don't make your boards there and you probably won't get copied
kinda like the Gdemu for the Dreamcast
has them built in china and is surprised when the clones came out
the chances of chinks otherwise importing your product to reverse engineer it and replicate it are rather low.

>>2622664
it's an old power factor correction unit
My dad wants the box so I'm gonna take everything out and probably use any of the caps that are good. Save any big lugs and breakers etc. A couple of the caps are bulged so we'll see what's still good. The unit is about 25 years old. My work is putting in a new one.

>>2622648
Undersize your microcontroller such that the code barely fits when written with assembly wizardry. Include arcane tricks in your analog hardware like tempco matching to obfuscate the mode of operation. Publicly release only obfuscated compiled .hex files. Use at least one IC that you don’t think gets manufactured enough in order to incentivise more fabs to make some. Secretly leak source code that’s actually just the Tiananmen Square copypasta.

>>2622648
Anecdotal but if the niche is small enough nobody bothers to fill it except very small players who home assemble their products

My father tried to make a business out of an automatic swamp cooler pump controller he made in the early 90s. He was in his early 30s
The controller was literally a 220V to 12V transformer powering a 555 circuit to turn on the relay to the pump every few minutes. The whole thing was inside a plastic enclosure and there were two knobs to control the pump turn on frequency (literally pots in the 555 circuit). The circuit was hand soldered on a PCB. He designed the PCB on paper and posted it to a company to get the boards manufactured
He was convinced he'd make a killing selling this "product". To the extent he epoxied the circuit to prevent reverse engineering. He called it "intellectual property"
This was an EE from a decent univ who thought a swamp cooler pump controller with a 555 brain would sell well

The average skill level of engineers has increased a lot these days.

>>2622757
how much did he make

>>2622762
He made no money, spent like 10k out of his own pocket. He gave out like 10 or 20 units to family and friends to do a test run. By the end of 2 months, almost nobody was using his product because the 555 in an astable configuration was not a decent enough logic to keep the coolers. The filter pads stayed too dry for the coolers to be effective

>>2622765
Worst of all, the product required the customers to call my dad who'd then come to their house, rip out their swamp cooler's pump wiring out, and attach his controller in the middle. He was wasn't a certified electrician either (not that it mattered much)
He envisioned that the distributors in other towns would do the installations

>>2622524
most guitar pedals are only 9V and anyway I'm asking because it seems like people on here only do digital 5V stuff or weird industrial motor stuff that's higher voltage

>>2622676
>the chances of chinks otherwise importing your product to reverse engineer it and replicate it are rather low.

https://www.youtube.com/watch?v=I6Oz2fqutw8

Chinks are thieves. They steal everything. It's the prime survival strategy for NPCs. They're all going to learn firsthand when the fighting starts. lmao

>>2618620
does anyone know if this formula for calculating "minimum transformer turns to avoid saturation" is applicable to coupled inductors made with toroidal ferrites? i'm trying to make a center tapped (push/pull) primary coupled inductor with a single output, driven by a square wave (50% duty cycle PWM.)

>UPS stopped working
>open UPS
>12V 7Ahr SLA battery is puffed up and at 5V
>need to order a new one for 15$
Has anyone EVER had a good experience with lead acid batteries on this planet? Lithium ion batteries may be inherently dangerous but they still ooze confidence and competence compared to SLA batteries. Don't even get me started on the self discharge. Can't store the fucking things for a few weeks without them dying

>>2622888
>Lithium ion batteries may be inherently dangerous
LiFePo chemistry is safer and higher density than SLA.

>>2622826
Yes, this equation is derived from faraday's law and assumes square wave input. The hard part is figuring out core characteristics. You can always also try using simulations (femm).

>>2622888
>Has anyone EVER had a good experience with lead acid batteries

lead-acids are reliable as fuck.
until they die.
every battery dies.
but none live as gloriously as the lead-acid
which is why they're in every alarm system, UPS, emergency light, emergency phone/intercom, and every car.

>>2622889
>LiFePo chemistry is safer and higher density than SLA.
Anon I will admit, I don't know much about the chemistries even though I have worked on a commercial moped BMS firmware before. It was a 13S3P pack

>>2622905
Maybe I'm just very unlucky. Every single lead battery I have used outside a vehicle has died very soon

>>2622916
>Every single lead battery I have used outside a vehicle has died very soon
You have to keep them off of the ground. Some batteries (non-sealed) have a liquid electrolyte (dilute sulfuric acid) that needs to be topped off or replaced periodically. Like other chemistries, discharging lead-acid batteries beyond a certain point will damage them.

>>2618713
please don't die

>>2618713
Shove something into the ground. Put one hand on the ground and pull the other two pins out. Ezpz.

>salvage transformer from SMPS
>ferrite halves glued together
>scrape visible parts of glue off
>gently pry apart
>no give
>heat up to 200 F with hot air gun
>no give
>soak in acetone/toluene mix for an hour
>no give
>soak in hot acetone/toluene mix for an hour
>no give
>soak in hot chloroform for an hour
>no give
what the fuck is this glue made of.

>>2622997
You wouldn't have this problem if you didn't gobble soi like your mum gobbles my cock, zoomzoom.

>>2622997
>what the fuck is this glue made of.
one word: gorilla

>>2622997
Did you try freezing it? lmao

>>2623005
i'm going to let it soak in chloroform overnight. if this doesn't work, i'll try freezing. last resort will be smashing it with a hammer in an autistic rage and buying some chinkshit transformers off eBay.

>>2623007
Try penetrating oil too. WD-40, even.

>Try to simulate picrel with 1 diode in KiCad
>works as expected
>add another diode in series
>suddenly current can flow backwards through them both

Is there any solution to this or should I just use LTSpice?

>>2622997
ultrasonic cleaning seemed to work for me when i removed glue-crust from a part i had from chinkistan as well

The Taliban and Iran are having a little skirmish. New Rambo movie coming in 2025.

>>2622775
People here still do a decent amount of analogue stuff. For which using single-rail supplies like a 9V battery is a shitty shortcut that results in speaker pop due to the DC-blocking caps filling when it's turned on. Nothing beats ±12V or ±15V for analogue shit, and I definitely see it here every now and then. Fuck SMPSs.

>>2622889
Yeah but it's not trivial to convert a UPS to run on LiFePO4. The charging circuitry is completely different, and you need a different undervoltage cutoff threshold. I've looked into bodging that circuitry into a UPS board I happen to have, but it's all being run by a PIC which sounds like a pain to reverse engineer the code of. Bypassing the existing battery circuitry entirely and just adding a LiFePO4 with its own protection and charging circuitry might work, may just have to spoof things with some resistors.

>>2623014
You're measuring two voltages, the only reason why the voltage between the two diodes goes halfway negative is because each diode blocks half the voltage when in reverse. Plot the voltage across R1, you should see that it's practically zero during the negative cycle.

ohm, you got any experience with those chinkshit rechargeable power packs? are they serviceable? i need to power a small keyboard and a 5w amp board+speaker

>>2623077
>are they serviceable?
The cells are spot welded together. The BMS is probably under the shrink wrap.

>>2619759
The zener simply regulates the voltage at 10V. Why it's there, well it's most likely due to the physical circuit than the theoretical diagram. Something on the physical circuit must be causing the voltage to fluctuate at that note to require an extra zener diode, most likely from the relay coils being switched off. The engineer most likely realized that during switching the voltage would spike and the zener there is for clamping the voltage to 10V and shorting anything higher than that to ground to prevent it from going further down the line along Vcc. Remember, VCC is generated by lm7810, and it won't be able to regulate the voltage if the spike is coming from Vcc, only if it's comming from the P/S voltage pin. IMO you might even be able to get away with not including the zener depending on how sensitive the entire circuit is, usually the flyback diode with no snubber is good enough to keep spikes at a minimum, but it's still good practice to include that zener, especially if signal integrity is important for whatever those OP amps are generating. A fluctuation on Vcc will show up on the output of the op amps.

>>2619923
use an eraser on the contacts to get rid of oxidation. It usually works unless it's badly oxidized.

>>2620262
You still have 2x 1W resistors, but by putting them in series, you create a voltage divider that dissipates half as much as originally, so yes, technically you end up with 2W. You could also take 2x 12000 ohm resistors in parallel and get 1x 6000 ohm 2W resistor by creating a current divider. As long as you remember that each individual resistor is still 1W, and that the power dissipated is divided equally among them, you're fine.

>>2620988
Do you have a power source on top of that voltage? If so you can use a buffer, then transmit that to your isolated sensing circuit with an optocoupler.

>>2621695
you should ditch the train of diodes (pun intended) and replace it with a zener diode. Obviously this type of voltage regulation is highly inefficient and you must make sure that you have a limiting resistor to prevent the diode from blowing up, but it's very simple without going into more complex methods such as switching regulators, although if you're up for some learning, I highly recommend to look into buck converters.

>>2623119
I do want to learn, just that googling the question came up with very dense subject matter that I couldn't really follow, it was easily 11 years since I did it in college, and despite being qualified to PAT Test and being a competent electrical and structural solderer, I've not sat my ass down to really learn what I'm doing, so any advice and tips is always helpful, so thank you very much!

Why resistors work from both sides?

>>2623125
There are videos on youtube that go over the thing, I don't know how good your math is, but algebra and a bit of calculus is usually all that is needed. If you're interested in getting familiar with the different type of switching supplies, you can start here:
https://www.youtube.com/watch?v=nbKwUSH9NiY

Then you can go and read up on them in more details, but usually you can do a lot of the design by trial and error if you don't feel like making calculations, but you do need some test equipment for that. If you want a deep understanding though, there is no short cut, you need to open up the textbooks and read up on it on your own, although fair warning the math can get a bit complicated and you might have to brush up on calculus. One thing to note, there are a lot of ICs that do pretty much everything for you. If you go right now on digikey and look at buck converter ICs, they will most of the time tell you exactly how to build the circuit in the datasheet, no calculation necessary, or very easy ones such as basic high school algebra. Sometimes they even have online design tools where all you have to do is put your requirements (for example, input voltage, output voltage, output current) and the tool will automatically design the circuit with all values for you.

>>2619759
I don't think D1 is being used to clamp VCC, at least not only. I think it's being used with R1 to regulate the "?" node that's feeding relay K1, because otherwise why include R1 at all?

>>2623126
They do not care which way current goes.

>>2622997
ended up destroying it. the ferrite halves were epoxied and the solvents didn't so much as touch the epoxy seam. even after smashing it in half, i couldn't get the epoxy seam to break with my hands. for fucks sake. chinkshit transformers it is!

>>2623377
at least you tried, anon.

>>2623007
>>2623377
Nice.

a truth bomb from kamala. EEs take note.

>>2623578
>truth bomb

and without china, it wold cost as much as a car.
which is why we've joined trump's economic war on china.
so you wont be able to afford anything better than a Nokia in the future.

>>2623614
No, most high-end semiconductors are made in Taiwan. Our pocket electronics might cost twice as much without China, but not ten times as much.

i need to build a mains phase angle controller to be interfaced with an MCU.

i've looked up the usual means of doing this: PC817 optocoupler zero-cross detector firing an interrupt in an MCU (with phase delay offset in software), with the MCU triggering a non-zero-cross optocoupler like a moc3020.

is there an alternative (or a more integrated IC) that lets me get away from having to do zero cross detection in software and still lets me do phase angle control?

>>2623614
Let me guess- you love Ukraine and hate Russia. Are your booster shots up to date?

>>2623056
I have a +/-15V linear supply with a 2x lm1875 stereo and it still pops like hell when I turn it on. no dc blocking cap.

>>2623629
Looks like split-rail LM1875 circuits often use DC blocking caps anyhow. Sure there's nothing even on the input?

>>2623619
What you describe is basically the same as what I did with my circuit. But there's one or two alternatives.

One is use a bridge rectifier, and put a switching element inside that. If you use an SCR, then you still need zero-crossing detection, but can switch the SCR directly with the MCU instead of needing an optotriac. This also makes the zero-crossing doable without an optocoupler, I think.
You can put a high voltage MOSFET there instead of an SCR, which removes the strict requirement for zero-crossing. That said, I would want to PWM that FET at a significantly higher frequency than mains, which is probably not great for noise reasons. I don't think it's doable to get a capacitive dropper giving you power relative to the FET's source due to the high frequency components, but a resistive dropper works. Your resistors will get kinda toasty. You can probably use a capacitive dropper if you only turn the FET on or off for entire mains half-cycles.

The other method is to construct a normal potentiometer-based phase-fired dimmer, and then use a vactrol (or other voltage-controlled impedance) instead of a potentiometer. Check the voltage rating of your LDRs.

Hi, I’ve been trying to fix this Taiwanese mobo for a while now, tl;dr can enter BIOS but the thing freezes after a few seconds and when it does this, the whole thing stops working, no beeps or anything. PCH's heatsink gets rather hot and I noticed this area pic related (I think is a buck converter or something) has an encased inductor which gets really hot and spits out 1.8v for some value called “GFX_CPU”.
See I downloaded this program called BoardViewer which I’ve been using as a guide but some values are missing regarding CPU voltages, I have a rather superficial understanding of what I should be doing here so bear with me.
From what I understand the main voltages of a CPU should be around 1.2volts, so maybe there’s something wrong with this area? Again, the inductor gets really hot while the others remain warm (there are 3 more inductors all controlling VCORE, which should be 1.2v after a quick search.) so maybe that’s the reason it’s a bit over 1.8v?

>>2623619
>>2623641
Forgot pic.

>>2623644
If they're not BGAs, I'd pre-emptively swap out the semiconductors making up that buck converter. Maybe just a reflow could get them to work. It may also be that there's some shorted windings in the inductor, but I can't see why that would happen absent any other faults. Might as well swap it out too though, inductors are cheap.

>>2623626
Akshually, Biden seems to be on the offense trying to bring semi conductor fabs back to the USA, and defending Taiwan from China as long as it's not done. While orange man did nothing of note. iPhones are still assembled in China, not Taiwan, all iPhone users are traitors.

>>2623672
>iPhones are still assembled in China
Aren't they being made in India now? Some of them at least.
>turns any political sentiment whatsoever into biden v trump
imagine having the american duopoly living rent-free inside your head

>>2623675
Apfail tried to migrate fabs to india but only managed to get a 50% failure rate, so no, they really aren't being assembled anywhere near india.

>>2623675
>imagine having the american duopoly living rent-free inside your head
Consider how dumb the post I replied to was.

Everybody point and laugh at the confused guy who cut his dick off for globohomo. >>2623681

>>2619261
>disjunctor

>>2623653
Damn, I've got another board of the same model but I'd rather not trash it for spares.
Is there a way to know if an inductor's got shorted windings while still mounted? It's thru-hole, kinda looks like a black dice, program says it's 50uH, guess it's picohenrys or something of that sort. It's got little to no resistance so it makes me assume it's fine, still gets really hot after a while and I can sorta hear a sizzling noise coming from somewhere when it and the PCH get hot. Another problem I've got with these is that I don't think my heat gun can desolder these, I've tried desoldering components off a shit motherboard and I sorta butchered the whole thing because the surface dissipates more heat than the solder or whatever on the SMD absorbs.

On a semi-related note, I tried searching for a solution/tutorial explaining this whole GFX_CPU thing on youtube and I found several videos by pajeets, all with unassuming titles in English but narrated in their do-not-redeem speech and sadly no subtitles.

>>2622997
https://youtu.be/IOwT8GkvIjs

>>2623783
>I've got another board of the same model but I'd rather not trash it for spares
I meant more just buy the replacements off Digi-Key. Get some chip-quik while you're at it.
>Is there a way to know if an inductor's got shorted windings while still mounted?
Low voltage ring tester. I think a circuit/project for one got posted a thread or two ago, pretty sure it was this one:
https://danyk.cz/avr_ring2_en.html
Basically it uses the inductor as part of an LC oscillator with a low amplitude, so it won't trigger any semiconductors. It basically measures the Q factor, so you can tell if there's anything strange going on with the inductor.

>>2623740
Shh… the IEC will hear you and adopt that term as a standard, like rectangular resistors. And logic gates.
Luckily we saw through those idiots and ignore everything they (or will ever) do.

>>2623832
what power cables do your power supplies use, anon?

>>2623841
DIN

>>2623740
Did you think that post was serious? lmao dumbass

>>2623858
Whoops, no. I meant to reply to this one >>2619209
Which I do think was serious

how would you go about switching a bunch of mains led lamps independently from an arduino/esp?
i thought about a relay for each lamp in parallel on the mains side but i don't want to die and it's surprisingly hard to find out what the proper enclosure stuff is.
they're those T5 fluorescent tube type things. can i modify the lamps to have a switch after the internal driver, on the LED strip itself, which should be a much lower voltage?

>>2619266
Oldie but goldie

>>2618713
Just short it to trip the breaker then pull em out

>>2623902
If the LEDs are in series, and/or each LED chiplet inside each LED is in series, the DC voltage into the strip may well be higher than mains.

I don’t know much about arduinos, but if you’re worried, you could get an inexpensive mains switching outlet that has one of those cheap remotes that are everywhere, and hook your arduino up to those buttons (i think these are IR remotes).
If an arduino runs at whatever voltage the remote does, even better.
I’m guessing the arduino has an A/D converter, you might be able to hook it up to a phototransistor (or even directly to the LED) and figure out the IR pulses it uses, and program your arduino to do that.

I want to make an mp3 player for a 95yo grandma so that she can listen to audiobooks. She needs huge separate buttons and massive segmented screen for chapter number, so I can't go and buy such thing off Amazon. There's something similar for disabled people but it costs a ton and is not available in our country.

Anyways, I would like to know if it's possible to do this on ESP32 or Arduino? Cause I kinda know how to work with them on hobby level and I can 3d print the buttons and the case, and do the simple wiring.

>>2623979
Extremely easily, yes. You can even do it the easiest way by slapping a pi or arduino with linux on it and set it up in kiosk mode with, say, clementine. Absolute 0 effort except packaging it.

got a bunch of old soldering irons that just don't melt the solder and are weak as fuck. I'm looking through amazon but there seem to be dozens of different kinds with reviews that leave me paranoid thinking they aren't real or reliable.

anons, recommend me a good hot soldering iron that will melt solder like butter, preferably without a huge desk footprint but if thats part of a weak soldering iron and I need the box that sits on the desk then so be it.

>>2624099
Hakko FX-888D or Weller WE1010.

>>2624099
Order direct from the manufacturer if you decide on Hakko or Weller. Amazon sells used shit as new at inflated prices and should be avoided whenever possible.

>>2623991
>easiest way by slapping a pi or arduino with linux on it

as someone who has tried this for years, i can assure it's a supremely bad idea.
unless you're willing to put up with weekly phone calls to troubleshoot problems.
what you wanna use instead is an idiot-proof commercial product.
i got several cheap choices that use the TV as display and sound source.
any old lady can handle a TV.
the WD Live Hub Media center ($7 used) comes with a 1TB HDD, while the cheapo android box ($4) has a slot for micro SD card.
but you'll have to redo the remote control by soldering large buttons instead.
(android box can use a wireless mouse and have huge icons , so no need for remote)

>>2623979
Get together with the kerbal space programme controller guy—-they look like that.

>>2624099
>old soldering irons that just don't melt the solder and are weak as fuck

99 times out of 100, the problem is you have a cheap or dirty tip.
acquire a good quality tip (Weller or Hakko) and scotch tape to your iron; it'll be magic.
truly, any heat source will do when you have a good tip: matches, a candle, stove-top, magnifying glass.

>>2624120
Linux running on an arduino is extremely rare

>>2623979
https://www.ebay.com/itm/394612202110
Put a PCX lens over the screen to magnify it, and wire up big buttons. Try to mod the circuit (or firmware) so it defaults to the e-book reader.

>>2624153
>PCX lens
cylinder lens

So this is the keyboard pinout of my laptop. How do I find out which abbreviation does what?

I've got this strange situation that I might need help troubleshooting. Context:
>big commercial stage light switchboard, digitally controlled by an internal AT89
>three phase + neutral + GND input
>12 breakers on the front, 12 single-phase output sockets on the back
>4 breakers for each phase
>has a massive TO-3 TRIAC for each socket, each with a 6-pin optoTRIAC and massive toroidal choke
>all TRIACs are bolted to the same heat-sink
>one open-cold/closed-hot thermal switch bolted to the heat-sink
>a single fan is connected to phase 1 through this thermal switch to neutral, connected before the breakers
>an individual AC step-down transformer is connected to each phase to power the digital board
>a slow-blow fuse for each AC step-down transformer, none of which are blown
Symptoms:
>after running for some time, all four breakers for phase 1 trip
>residue from a dry powder fire extinguisher can be seen in places, fan included
Because the fan isn't directly connected to after the breakers, I don't think the fan itself is the problem. Guess one is it may be that the thermal switch and/or TRIACs are being shorted to the heat-sink such that all four breakers of that phase trigger at once though. Apparently dry powder extinguisher residue is acidic, so that could well be the problem. Guess two is a crowbar circuit detecting a fault, but the only other power packages I see are BC557s and 7805 regulators. Guess three is the breakers also being RCDs, but I saw no evidence of that.

I'll try making electrically insulated thermal interfaces for both the thermal switch and phase 1's TRIACs for starters, and replace or at least properly wash out the fan. It's held on by nylocks though.

Any other ideas? And can someone tell me what you'd need a 50mm wide toroid for with a TRIAC? I thought maybe it's doing some sort of line-synchronous or ZVS SMPS stuff, but it's labelled "choke" on the board, not "inductor". Really just noise suppression? The bottom of each toroid is potted.

>>2624246
I'm guessing KB-SIx are rows and KB-SOx are columns of a matrix. Approximately that is, not like it's a simple square grid. Easiest way is to just plop a DMM (or logic analyser) on it and measure what keys cause which lines to change. I think maybe there's somewhat standard keyboard layouts that are what common scan-codes are derived from, but I haven't looked into that.

Fixed up an old 16:10 monitor that had been languishing for years.
Feelin' pretty cash

con: it predates HDMI
Might also be the reddest screen I've ever seen, wish I had a color calibrator

>>2624418
What was the problem? How did you fix it? Post pic of your peencel.

>>2624429
99% of monitor faults is a busted cap in the power supply circuit
Never toss a screen before opening it!

>>2624432
>99% of monitor faults is a busted cap in the power supply circuit
How many monitors have you repaired?

>>2624381
Gotta see if anybody I know has access to a logic analyzer. It would be kind of funny to build my own custom Keyboard PCB even though I have 0 experience in EE.

>>2624438
1, i'm basing this off what my teacher told me back when the monitor broke

>>2624447
Search altavista.com for "capacitor plague". lmao

>>2623873
Did you think I care? Lmao dumbass

>>2624448
oh lmao, checks out.
I have to imagine they're still the most volatile component tho

The ganged circuit breaker on the left says 30 and the one on the right says 40 (the plastic cover is broken so you can see the 40 twice). Is the number per leg or per breaker? That is the 30 two 30 amp circuits or two 15 amp circuits. I’m trying to convert one 240v circuit to two 120 v circuits. The two new circuits will be 20A each.

>>2624549
>two 15 amp circuits

wouldnt make any sense to ADD the capacity of two breakers.
for reasons which should be obvious.
so it's 30 & 30.

Does anyone know what this footprintname means? LED_0402_1005Metric_Castellated
I thought castellation refered to castellated PCB holes. Is the LED in picture "castellated"? Don't all smallish SMD LEDs (<=1206) look like that? The reason I am asking is this "castellated footprint" has both pads stretched horizontally and they are REALLY close together, almost touching, which is kinda gay.

>>2624686
forgot pic

This is what I am talking about

why don't they make breadboard power rails with 3 rails for v+, ground, and v-

>>2624691
I just use the outer-most red rail for V+, the outer-most black/blue rail for V-, and the two inner-most rails for 0V. Almost all my parts will have their positive and negative supply pins on opposite sides, so it works out fine. Doesn’t work with 555s since they’re the devil’s child.
I should make one of those breadboard power supply PCBs with such a layout. Maybe an LM317 and LM337 with a dual-gang pot for adjustment and an AC input. Or a rail-splitting op-amp with class-AB output stage and a DC input. Or just a 3-pin connector to a split-rail supply.

>>2624691
>3 rails for v+, ground, and v-

they come with 4 rails, sherlock.
just look at it, 2 at the top + 2 at the bottom = 4 rails in precise numerical quantity.

>>2624686
youre reading too much into it. just use the footprint that makes the most sense for the part you want to use. and fuck built in footprints. i remade all the standard sizes for smd parts because the defaults are usually retarded and designed for solder pasting

>>2624762
yes i make my own too, just comparing with the KiCad library as some of them look nicer and have courtyards and dots in the right place just like i prefer. KiCad usually provides at least two sizes, the larger one is for manual soldering, similar to IPC compliant L,N,M that you can generate in Altium or download from Snapeda etc. and I usually use the M size as it is the largest. But Snapeda and similar sources are utter shit. I don't use them anymore. grabcad is great for 3d models, if you are patient enough to find good ones.

>>2624762
>the defaults are usually retarded and designed for solder pasting
I find the default 0805 footprint easy enough to solder by hand with a 1.2mm screwdriver tip, but for smaller sizes maybe it's worse. There's always KiCAD's hand-soldering footprints, they looked sensible last I checked.

Also how do you handle custom footprints and symbols when you upgrade KiCAD versions? Just put them all in a custom .pretty instead of having them in the appropriate "Resistor_SMD"? Or is there a better way?

can anyone ID this manufacturer logo? Its old RAM, pre-PC66, its either EDO or FPM type

SAC305 or SN100C/Sn100Ni+ (tin, copper, nickel, tiny amount of gallium, Sn99.25Cu0.7Ni0.05(Ge)) for lead-free solder? Anyone tried SN100C?

SN100C info (scroll to "Enter SN100C"):
https://hackaday.com/2020/01/28/lead-free-solder-alloys-their-properties-and-best-types-for-daily-use/
https://nz.rs-online.com/web/p/solder/1363148