/ohm/ - Electronics General: Assorted Flavours edition

[Anonymous No.2429688]

Thread out of stock:>>2425865

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

>Incredibly comprehensive list of electronics resources:
https://github.com/kitspace/awesome-electronics
Additional resources below:

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

>Don't ask, roll:
https://github.com/Rocheez/4chan-electronics-challenges/blob/master/list-of-challenges.png

>Archive of Popular Electronics magazines (1954-2003):
https://worldradiohistory.com/Popular-Electronics-Guide.htm
>Microchip Tips and Tricks PDF:
https://ww1.microchip.com/downloads/en/devicedoc/01146b.pdf
>Li+/LiPo batteries required reading:
https://www.elteconline.com/download/pdf/SAFT-RIC-LI-ION-Safety-Recommendations.pdf

>Books:
https://libgen.rs/

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

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

>Recommended Components/equipment:
Octopart
eBay/AliExpress sellers, for component assortments/sample kits (caveat emptor)
Local independent electronics distributors
ladyada.net/library/procure/hobbyist.html

>More related YouTube channels:
mjlorton
jkgamm041
EcProjects
Photonvids
sdgelectronics
paceworldwide

>microcontroller specific problems?
>>>/diy/mcg
>I have junk, what do?
Shitcan it
>consumer product support or PC building?
>>>/g/
>household/premises wiring?
More rules-driven than engineering, try /qtddtot/ or sparky general first
>antigravity and/or overunity?
>>>/x/

[Anonymous No.2429691]

shit you're telling me i had smt tl431s in my chinky assortment of smt transistors all this time? and i've been designing boards with tht ones?
>inb4 they're tl432s

[Anonymous No.2429699]

I posted in the last thread about my plans to make a hydraulic forge press to make some damascus billets
After looking for a while i found this hydraulic cylinder which can provide about 15tons of pressure. Should be alright i think.
I now need
>an oil tank
>a hydraulic pump
>a motor

[Anonymous No.2429702]

>>2429699
Would this motor work or is the power too low?
https://www.amazon.de/hydraulic-double-acting-tipper-remote-control/dp/B08JP932S4?ref_=ast_slp_dp
>15L Tank
>3200 PSI
>Turn rate (i think thats what it is) 2850 R/min
>DC 12V
>1,6 KW with 3 KW max
I'm considering this because its an all in one solution and i dont know shit about pneumatics and which pump i need and which motor, etc.
At the same time im worried its just not strong enough.
Anyone know their way around this by any chance?

[Anonymous No.2429806]

My regular "plug the part name into AliExpress" technique isn't working ... What do bros?

[Anonymous No.2429819]

>>2429806

[Anonymous No.2429881]

>>2429806
you can go higher on milliamp hours, just not voltage

[Anonymous No.2429900]

>>2429806
>plug the part name into AliExpress

[Anonymous No.2429923]

>>2429819
>>2429900
Infeel stupid now, thanks for the help

>>2429881
I was worried the third cable would do something different

[Anonymous No.2429927]

if I keep AC connected to a transformer, even if I am not using it to power something, it still gets hot/warm. Why? Does it still keep consuming energy even if nothing is hooked up to the secondary?

disregard my safety, let me die if I have to, just curious about why its hot even when nothing is connected to the secondary.

[Anonymous No.2429931]

>>2429927
You're should switch the primary.

[Anonymous No.2429932]

>>2429927
The primary and secondary coils are coupled with an iron core. It's the core that's heating by induction.

[Anonymous No.2429936]

>>2429927
How could something not draw power if it's still connected to power? You grew up with smart phones, admit it.

[Anonymous No.2429938]

>>2429936
Im old, just dumb as fuck. when a computer power supply is plugged in, but nothing is drawing power from any of the cables, it isn't still consuming energy, is it?

be patient with my old retarded ass. I struggle with smartphones even. Some of us aren't blessed with common sense or neurons.

[Anonymous No.2429943]

>>2429938
>it isn't still consuming energy, is it?
Yes. ATX power supplies have a standby voltage for USB ports and switching on the 12V side of the power supply. Older AT atyle power supplies used a hard switch (when it's off, it's totally off).

[Anonymous No.2429949]

>>2429943
>AT atyle
AT-style
should've just type AT
lmao

[Anonymous No.2429952]

>>2429938
>Some of us aren't blessed with common sense or neurons.

No, you just don't READ or take anything seriously enough to study. That's lazy not a learning disability and age is no excuse (I'm old and tired of hearing that tripe).

Stop being you and your life will improve.

[Anonymous No.2429958]

>>2429952
Maybe Anon is a busy guy. What if he's in the jungle right now looking for Bigfoot? That's not lazy.

[Anonymous No.2429961]

>>2429958
Everyone has time to learn useful things. Refusing to use that time for useful things is their error.

[Anonymous No.2429966]

>>2429961
>Everyone has time to learn useful things.
Have you ever seen the dude that plays guitar with his feet?
https://www.youtube.com/watch?v=zUF5ygvai1c

[Anonymous No.2429971]

>>2429938
Okay then I'll break it down for you since you're not a zoomer.
Anything plugged into the wall uses power. Unless there's a physically hard-wired switch to cut the mains power (like light switch.) Some ATX power supplies have a mains switch, some don't. Phone charger? That pulls a small amount of power when it's not charging anything. TV? Uses power any time it's not unplugged.
Buy a power strip and use it.

[Anonymous No.2430036]

>>2429971
Man, you're all sour apples today. What's going on with you, anon? Tell me about ya mudda.

[Anonymous No.2430046]

>>2429971
>Buy a power strip and use it.

buy a power meter first.
when i got one, i saw that all my computer stuff was drawing 40 watts even when everything was off.
however, there was no need to buy a power strip coz i already have 6 of them wired in series to power everything.

[Anonymous No.2430083]

Which EE courses cover line coding / transmission lines, serial protocols? I've never heard of stuff like NRZI.

[Anonymous No.2430113]

Any industrial electricians in the house? >>2427217

[Anonymous No.2430149]

>>2430083
No clue, but I can recommend Ben Eater’s YouTube series on communication protocols and error correction. Aside from those I’ve just been browsing Wikipedia for the specifics of certain protocols, modulations, and encodings. Also articles on more general things, like Shannon-Hartley.

[Anonymous No.2430254]

>>2429952
>Stop being you and your life will improve.

>don't just bee yourself
pic related

[Anonymous No.2430260]

What do you think about the idea of a three multi-color LED indoor thermometer? Each LED has three colors, so the output will be a tertiary number with three colors each representing one bit (trit). So the range is from 0 to 27. In the F mode, it will signify an offset from 60F. Or as is in the C mode. I want to give it to my mom as a birthday present.

[Anonymous No.2430261]

>>2429688
Hey I hope this is the right area to ask. I'm curious to know how long I could run a 1600W 120VAC heat gun from that dewalt DCB1800B with 4x 20V/60V 15AH DCB615.
I tried to search engine the calculation but I couldn't quite find the right one.
https://www.leister.com/en/product/Triac-ST#TechnicalData
https://www.dewalt.com/product/dcb1800b/1800-watt-portable-power-station-and-simultaneous-battery-charger
https://www.dewalt.com/product/dcb615/dewalt-flexvoltr-20v60v-max-150ah-battery

Thank You.

[Anonymous No.2430263]

>>2430260
>give it to my mom as a birthday present.

it's your mom, she'll love it even if you give her dog-shit on a stick.
and your idea seems on par with that.

[Anonymous No.2430276]

>>2430263
Are you a wang-less man in a tutu? Are you about to commit a mass shooting for dicscard?

[Anonymous No.2430283]

>>2430276
>wang-less man in a tutu?

this is very unfair.
seems you know everything about me.
but i know nothing about you.

[Anonymous No.2430287]

>>2430283
I'm the ship's cook. John Long, they calls me.

[Anonymous No.2430298]

>>2430261
I may have figured it out @ 45 minutes?

E = V * Q
E = Energy (Watt-Hours)
V = Volts
Q = Energy Capacity (Amp-Hours)
20V*60Q=1200E

and

Wh = W * T
Wh = Watt-Hours
W =Watts
T = Time (In Hours)
1600W*.75T=1200Wh

Anyone correct/verify?

[Anonymous No.2430300]

>>2430260
Depending on how you multiplex the LEDs, it may be easier to just have a potentiometer for each colour and have the RGB value continuously variable. Either through analogue current mirrors or through a PWM circuit.
Remember, the first idea you come up with is probably elegant in one way but stupid in other ways, so constantly ask yourself “is there a better direction to attack this problem?”. For large projects, I draw out a “design compromise document” where for every decision I note the pros and cons.

In this case, the display is the most central part, so you should start experimenting to find what display arrangements look readable and are easy to drive. I’d recommend using 7-segment decoders like 41511s while multiplexing each digit.

The other central part will be battery life and convenience.

>>2430261
So what, it has 4 60V batteries? 2 in series and 2 in parallel to get 120V? At 60V I believe the capacity is 1/3 of the 20V capacity so 5Ah, which will put the total capacity at 10Ah due to the 2 in parallel. 1600W at 120V is 13.33A, so 10Ah would last you 0.75h, or 45 minutes on full-power.

[Anonymous No.2430302]

>>2430298
Stop getting units and symbols confused
Power = P, measured in watts W
Energy = E, measured in joules J or watt-hours Wh
Charge = Q, measured in coulombs C or amp-hours Ah
Time = t, measured in seconds s or hours h

>20V*60Q
What the fuck are you talking about, where did 60Q come from?

[Anonymous No.2430304]

>>2430300
>So what, it has 4 60V batteries? 2 in series and 2 in parallel to get 120V? At 60V I believe the capacity is 1/3 of the 20V capacity so 5Ah, which will put the total capacity at 10Ah due to the 2 in parallel. 1600W at 120V is 13.33A, so 10Ah would last you 0.75h, or 45 minutes on full-power.

wouldn't it have an inverter to go from 20VDC to 120VAC?
I'm pretty sure the 15AH advertised is at the lower 20VDC.
Which actually, i guess is running at 18VDC, right?
>>2430302
60Q = 4 * 15AH batteries.

[Anonymous No.2430342]

>>2430304
>wouldn't it have an inverter to go from 20VDC to 120VAC?
It's a hot air gun, doesn't matter if it's AC or DC. Probably uses seperate coils for different heat settings, though if it uses TRIAC dimming then it needs a pure sine inverter.
>I'm pretty sure the 15AH advertised is at the lower 20VDC.
Yeah, that's why I converted it to 5Ah at the 60VDC. Both mean 300Wh of energy per battery.

Now I understand that you were doing the energy calculation, I thought the 60 was coming from the 60V spec.
But please write it as:
>Q = 4 * 15Ah = 60Ah
>E = 20V * 60Ah = 1200Wh
>t = E/P = 1200Wh / 1600W = 0.75h
The lower case on the "hour" is somewhat important. Also "watt" is meant to be lower case when it's referring to the unit, as doing so differentiates it from the person, but the "W" is still capital. "T" vs "t" is less important, since capital "T" is often used for time periods, while "t" is used for time as a variable.

/rant

[Anonymous No.2430424]

>desolder 18650s from 12V tool battery
>plan on replacing them with solder-tab 18650s
the top of the cells' tabs are captive to a plastic alignment piece
Well shit, gotta 3D print that then.

Also jesus desoldering plated through-holes is ass. There's basically no way to get rid of all the solder connecting a lead to the inside of a hole, even with wick AND a strong sucker. Especially not if I'm time-limited by the heat flowing into nearby batteries. I'll definitely invest in some desoldering needles, but even those wouldn't work on these wide pins without squashing them.

[Anonymous No.2430445]

it's pretty crazy that chinks can make me 5 10x10cm pcbs for just $2
I can barely buy one small blank pcb here for $2

[Anonymous No.2430471]

>>2430445
what's your workflow? i think i can get it under a dollar, if i use home-regenerated etchant and hand-paint or use an lcd lightbox for my resist

gonna buy a printing silkscreen too, might make solder mask easier

[Anonymous No.2430477]

>>2430471
workflow don't matter as that is the cost just of the pcb alone.
And for this kind of money diy makes zero sense anymore. The only time i even bother making my own pcbs is if for some reason can't wait 10 days

[Anonymous No.2430489]

>>2430477
>the cost just of the pcb alone
what kind of copperclad are you buying? I bought 10 slices of shitty single-sided fr2 for like a couple of dollars, each 5x10cm or so so that's like 5 of my small SMD boards each. Even FR4 isn't that much more expensive, though I'm helped in that regard since I scavenged like 80 offcuts from a former job that work really well when the board doesn't need to be more than 1cm wide.

A streamlined all-CNC system (not my current system) should be able to eliminate any hassle, so it's only like an extra hour or so of setup compared to sending it away to china. The three setups that work best here are:
>CNC router
>CNC laser + etching
>LCD mask exposure + etching
Naturally, drilling = manual work for anything other than a router, but with a nice laser-aligned drill-press (diy'd my own) it's not that difficult to get good holes. Single-sided SMD boards only are the real optimal location for home-etching, and a lot of simple prototypes fit that bill. Vias and plated holes on the other hand, yeah unless you've got electroless plating baths you're better off buying boards from china.
t. hand riveter

[Anonymous No.2430490]

>>2430489
i have cnc router and can make double sided pcbs no problem, but like i said, even with that it's simply not worth it, specially if you want to do extra shit like solder mask, unless i need the pcb the same day and only one copy of it, chinks are simply way superior choice

[Anonymous No.2430595]

my understanding is that the mofsets in PWM controllers fail closed.
i don't want this to happen. if the circuit were to fail open, that would be fine, but failing closed is unacceptable.
i want some sort of "thing" to make sure that if the controller fails, the circuit breaks.
how can i practically achieve this?
i don't know much about electronics. since a PWM controller is going to be "off" sometimes as long as the dial is not set to maximum,
i can imagine some sort of thing where if the circuit is ever on for more than like, i dunno 5 seconds or something, the power is cut.
of course, that means that i can never use it at 100% speed, but that's not really a concern.
i either want it to work "as i intend for it to" or to be totally disabled.
how would i go about doing this simply?

[Anonymous No.2430602]

Got one of these a while back: https://archive.vn/gMxLP#selection-1045.13-1045.95
Seems to work fine for a 7S lithium battery. Problem is getting it to work on a 6S lithium battery.
The instructions say to connect up the cells as with a 7S battery, starting from the battery -ve and just leave the last balancing connection empty.
I tried this, but the board's -ve to the battery +ve is about a cell's worth below the battery itself, and it won't permit current.
Did I make a mistake in thinking this thing would work for 6S and 5S packs (as the instructions imply), or am I just doing something wrong?

[Anonymous No.2430685]

>>2430595
The cheapest and most flexible option would be to use some tiny microcontroller like attiny and just do everything in software. For complete discrete solution (like pic related) you could use RC circuit to charge when pwm is high through a resistor and discharge to ground when pwm is low. If pwm is on for more than a couple of time constants comparator can be used to set SR latch to store fault condition.

[Anonymous No.2430701]

Any tips on replacing this tsop-6 mosfet? It is only rated for 20v 4.4a but I need it to comfortably pass 6.25A

Can I simply bodge on any power mosfet? Like I can recover one from a dead psu that will be very big and do the job nicely
Or do any in tsop-6 footprint exist that can take this extra power requirement

[Anonymous No.2430787]

can someone point me to an H-bridge schematic that converts a DC signal from a large voltage source to a smaller AC signal

[Anonymous No.2430844]

>>2430595
Crowbar circuit?

>>2430701
If the new FET takes significantly more gate charge or needs a higher gate voltage, it will just heat up more than the existing FET.

>>2430787
Class-D amplifier.

[Anonymous No.2430954]

>>2430844
>significantly more gate charge
How would I know, I can't even determine what the one on the board is.
I'm only assuming it's too small because that's what the people who make the board rate it at

[Anonymous No.2430958]

>>2430046
> i already have 6 of them wired in series
i too enjoy the smell of bunt plastic anon

[Anonymous No.2430981]

>>2430954
No part number? I hear rubbing the top with a fingernail can make them more visible, if it’s that laser-etched look.
Do you know what the FET is doing?

[Anonymous No.2430990]

>>2430685
>The cheapest and most flexible option would be to use some tiny microcontroller like attiny and just do everything in software.
i was somewhat "concerned" that that was the route i would end up going. i have done stuff with raspberry pi and arduinos before, and it seemed very easy to codify what i want to be done in terms of software.
conceptually, it could be solved with something like a NOT gate on the output, and i just reverse the label on the speed controller. 100% now becomes 0%, and if it short circuits, it's off.

[Anonymous No.2431036]

I have an old NRI ME5708 multimeter without a fuse. It has a single fuse socket. The back of the meter next to the fuse symbol says 250v FAST. No amperage. The amperage switch says both 200ma MAX and 20A MAX. How do I know which fuse to buy?

[Anonymous No.2431042]

>>2431036
>How do I know which fuse to buy?

common knowledge: a 20A fuse would screw up the current readings, so 0.2A it is.
actually i'd go for a lil higher, like 0.25 so you dont have to replace as often.

[Anonymous No.2431050]

>>2431042
Thanks m8

>common knowledge: a 20A fuse would screw up the current readings,

How do you know this, or what does that look like? Does the higher amp fuse give too much resistance to measure smaller amperage accurately?

I ask because there’s multimeters out there with both large and small fuse sockets. Mine only has the one.

[Anonymous No.2431052]

>>2430981
It's right there in the picture left of the white block connector.
58AF is all it says.
It switches on pci-e power to the slot when the controller tells it to.
It doesn't look to me at all like it's good for 75w at 12v, only one pissant source leg. It's been doing fine at 30ish watt but I've only really been playing games that don't hit the gpu too hard.

[Anonymous No.2431058]

>>2431050
>Does the higher amp fuse give too much resistance to measure

yes.
typically there's just a short wire between ground and the 20A range.
a fuse would add considerable resistance and throw readings off, unless remedial steps were taken, adding cost and complexity.

[Anonymous No.2431063]

>>2431058
>your explanation makes sense to me

I will take advice from the chinz knowing this often leads to death.

[Anonymous No.2431071]

>>2431036
Depends on whether it's the fuse for the 20A range or the 200mA range. Some multimeters won't even use a fuse for the lower range, but all the ones I've seen have a fuse for the larger range. If you're lucky there'll be silkscreen on the PCB (or an online manual) to tell you which fuse it is.
The lower range fuses are typically small ceramic fuses (often M205), while the higher range fuses are typically much more beefy, with peened-over end-caps and writing on the fuse body itself, often sold as dedicated DMM fuses. These can cost up to $20 (maybe even higher) if you have a particularly obscure fuse or expensive DMM.

As the other anon says, go for +10% or so on the reading. My meter uses an 11A fuse with its 10A range.

>>2431058
Horseshit. The presence of a series fuse dropping a fraction of a volt is hardly going to change the voltage across the current sense resistor. They use instrumentation current sense amplifiers anyhow.

[Anonymous No.2431079]

>all this hubbub about fuses
I always thought that was a spare .22lr cartridge holder.

[Anonymous No.2431082]

>>2431071
>current sense resistor.

no resistor, it's just a piece of copper wire with negligible resistance.
just the resistance of the fuse's spring contacts would be much higher.
besides which, the contact resistance can vary over time making it unreliable.

[Anonymous No.2431090]

>>2431058
>>2431071
Damnit.

>>2431079
>spare .22lr

That’s in 79 ford pickup trucks not in multimeters

[Anonymous No.2431093]

>>2431090
>not in multimeters
Maybe not in your Swedish Navy Spoon multimeter.

[Anonymous No.2431107]

>>2431093
>Swedish Navy Spoon

Thems fightin words.

[Anonymous No.2431118]

>>2431082
>a piece of copper wire with negligible resistance
That is the current sense resistor, and they're not usually copper, but rather some sort of more resistive alloy like nichrome. Even if it looks like copper, I'd imagine it's a copper alloy with higher resistance, since otherwise differences in soldering would cause significant changes in its resistance. It will be tuned to a certain resistance (usually 1mΩ or 10mΩ from what I've seen), such that a voltage measurement directly across the current sense resistor predictably corresponds to a current to be displayed. That way the resistance of the banana plugs and wires don't impact the current measurement.
If it were just a random piece of wire, how would you get a current measurement out of it?
>just the resistance of the fuse's spring contacts would be much higher.
Yeah, and even more so for the banana plugs. The fuse clips on 10A/20A ranges I've seen seem to be particularly high-tension for minimising contact resistance. So long as the power dissipated is less than a watt or so it's no big deal what its resistance is, it's not going to impact the measurement. Whether it's 1mΩ from the sense resistor, or 1mΩ from the sense resistor AND 16mΩ from the fuse and bananas, at 10A you still get a 10mV drop across the sense resistor.

TL;DR: watch EEVblog #344 where he takes apart a Fluke 17B. At 3:48 you can clearly see two fuses, the small one by the bananas and the large one to the side. At 6:30 he shows the high-current fuse, being an 11A fuse for a 10A range. The silvery metal loop (R41) is the high-current-range sense resistor.
Or literally any other non shit-tier DMM teardown.

[Anonymous No.2431121]

>>2431118
No wuckas. Bob's your uncle duck's guts flapping in the breeze. Bobby dazzler.

[Anonymous No.2431125]

>>2431107
Is this now an international incident? Somebody call... uhh...
Who's in charge again? Don't say Charles.

[Anonymous No.2431129]

I need a unity gain stable opamp that can source +/- 100ma into a 80 ohm load, running on a +/-15V supply

[Anonymous No.2431132]

>>2431125
Chuck? You know Chuck?

[Anonymous No.2431139]

>>2431132
I know him as Chuck Chuck Beau Buck.

[Anonymous No.2431142]

>>2431118
>>2431082
Anons. Get your shit together. Am I buying a 2A or 0.2A fuse or am I just getting the free one from harbor freight?

[Anonymous No.2431143]

So I want to see video footage coming from and be able to control a robot/drone from a long distance, I have an extra phone to spare. Has anyone done it like this before?

I was also thinking, it could be possible to just make a videocall to that phone, use it's camera to see what's happening, and have the data to control it, be sent over video signal via color code read via color sensors glued to the screen.

[Anonymous No.2431150]

>>2431129
At that level you’re looking at power amps, not op-amps. Be better off putting a standard buffer connected to a class-B stage.

>>2431142
Take apart the meter and see what input jack it’s connected to, no way of telling just from description. If it’s a large fuse holder I’d suggest 22A, if it’s a small one then 220mA.

>>2431143
2-way video data is a waste. Look at what the fpv guys on /rcg/ use. There may be a way of using cellular data, but generally they use dedicated analogue video transmitters.

[Anonymous No.2431155]

>>2431150
>Take apart the meter and see what input jack it’s connected to, no way of telling just from description. If it’s a large fuse holder I’d suggest 22A, if it’s a small one then 220mA

I don’t know large from small. If i measured the slot and compared it to the specs would that suffice?

[Anonymous No.2431159]

>>2431143
Back in my day we used a hot air balloon and binoculars to range our sausage-fueled rocket launchers.
Zoomers.

[Anonymous No.2431164]

>>2431121
come a gutser

[Anonymous No.2431168]

>>2431159
Nice idea, but I'm working on something land based. Like a remote claw espionage/sabotage bot

[Anonymous No.2431171]

>>2431155
I guess so? If it's for an M205 fuse (20x5mm) then it's likely the low-end one. Same for those oddball 25mm long fuses, probably. Just unscrewing the clamshell to follow the thick trace is a better idea though. Or measuring continuity between the fuse clip's pins and the 20A and 200mA sockets, but that requires having a 2nd DMM.

[Anonymous No.2431172]

>>2431155
>I don’t know large from small.

you're kinda of a helpless puppy.
20A fuses are likely to look like the ones on the left. they're 1/2-inch wide.
0.2A fuses are likely to look like the cylinders on the right. 1/4-inch wide.
i already told you it's the 0.2A you need.
the only thing you need to determine is whether it's 1-inch long or 3/4-inch long.
so, measure the fuse holder.

[Anonymous No.2431227]

>>2431150
>At that level you’re looking at power amps, not op-amps.
OPA551?

[Anonymous No.2431233]

>>2431227
Idk man, read the datasheet. Short-circuit-current is usually not taking into account distortion, so you’ll want to look for both maximum operating currents and power dissipations. Calculating heat dissipation isn’t wholly trivial, you’ll need to figure out the rms voltage drop and multiply it by he rms current, I think. Sim it if you’re worried.

[Anonymous No.2431252]

Is there a word for a filter that does pic related?

I want to get rid of those big spikes, but a basic lowpass filter is going to smooth out smaller fluctuations I want to preserve. I need a filter that removes high amplitude high frequencies but lets those frequencies pass at lower amplitudes.

[Anonymous No.2431265]

>>2431252
>Is there a word

one word is ''manually''
i use Goldwave (Audacity works too), listen for the offending part, zoom into it and silence/attenuate the culprits one by one.
there's a pops-and-clicks remover filter in both programs, but i havent found it very useful.

[Anonymous No.2431268]

>>2431252
Might be able to get that with some sort of nonlinear filter, say using back-to-back diodes or zeners instead/in addition to the resistor. They pass more at high amplitudes though, which is the opposite of what you want, so you’ll need to combine them with some sort of negative feedback circuit. That or make the filtration with a “DRC” LPF and subtract it from the original signal.

[Anonymous No.2431279]

My inverter TIG welder suddenly started to always run at max power, but the driving circuitry seems to know about it as the display also says 240A as soon as I press the button/pedal. But it only goes up to 240A once I trigger the button/pedal, on idle it's back to the lowest 5A, and current regulation seems to be working normally in SMAW mode, does that mean I should be looking for the fault somewhere in the pedal input area? I guess if the main driving MOSFETs were blown, the current setting display wouldn't know about it. It's a Tuson Pegasus HF 160A AC/DC, chinkshit import.

[Anonymous No.2431293]

I have taken apart an old car battery charger. It has a switch that lets you chose from 6 volts and 12 volts. When i test it with a voltmeter it appears to be working, but also wire 1 and 2 have no resistance between themselves (meaning they are connected even when i remove the switch). How does the switch change the voltage if it's switching the "same wire"?

[Anonymous No.2431296]

>>2431293
I think i figured it out? Is pic related how it works? I might take it apart just to make sure

[Anonymous No.2431342]

>>2431296
>Is pic related how it works?
Yes.

[Anonymous No.2431400]

So, whom has the most "fantastic" project?
What is it?
Whom is King of genius?

[Anonymous No.2431405]

>>2431400
hi i'm retarded

[Anonymous No.2431417]

>>2431405
Great!! We'll crown you as winner of the "special" olympics edition, sweetie.

[Anonymous No.2431423]

>>2431417
>sweetie
sweaty

[Anonymous No.2431435]

>>2431423
>sweaty
Then take a shower if you stink, sweetie.

[Anonymous No.2431438]

>>2431435
My cloaca smells like death. Ever get that not-so-fresh feeling on a moist summer's eve?

[Anonymous No.2431446]

>>2431438
I don't know, anon.
Maybe, try bathing more.
You could try soap, or get your carer to wash it for you.

[Anonymous No.2431449]

>>2431446
Are you volunteering to be my caretaker (hole washer)?
>faith in humanity status: RESTORED

[Anonymous No.2431452]

>>2429971
not mentioning that it only draws a few dollars worth of power every year
I fucking hate old boomers who unplug everything after they use it so when you go to boil some water or make toast or turn on the TV you fucking can't
fucking boomers

[Anonymous No.2431457]

>>2431449

[Anonymous No.2431462]

>>2431457
It's the kind of stank that doesn't wash off.
brb gotta drain pus and douche bile salts/mucus-blood hairballs from my designer slit, then order some 100x markup breakout boards from adafruit to support black lives.

[Anonymous No.2431466]

Maybe kind of a unrelated question, but how would you make a sensor device that differentiates between two kinds of cloth, organic vs synthetic, both are white.
I thought about reflectance spectroscopy to find out if there are signature bands in the spectrum I can check with specific wavelength LED. I don't have the equipment to perform such tests tho.
Maybe some kind of ultrasound sensor? Idk

[Anonymous No.2431475]

>>2431462

[Anonymous No.2431476]

>>2431466
What are the specifics? Is this a generic "organic vs synthetic cloth" sensor that works on any piece of fabric or it's going to always receive the exact same color and thickness and only the material will change?

[Anonymous No.2431477]

>>2431475
That would cauterize my "vulva". Good to know you're pro-genital mutilation of transwahmans. Just like Adolf Hitler!
>baka

[Anonymous No.2431481]

>>2431477

[Anonymous No.2431484]

>>2431481
Where did you find my gizmodo employee profile pic?
DELET

[Anonymous No.2431490]

>>2431476
>it's going to always receive the exact same color and thickness and only the material will change?
Yes. The process is as follows
>Either fabric A or fabric B falls down a chute
>Sensor detects something
>Sensor checks if it's fabric A or B
>Actuator separates fabric by type

[Anonymous No.2431500]

>>2431462

[Anonymous No.2431506]

>>2431490
If you can make a repeatable sensor reading then reflectivity might separate the two, or light transmission, shining a laser through the fabric. These require the fabric to always have a specific positioning. There might be subtle differences in color that a good RGB sensor could detect even without perfect positioning. If it's a consistent size, you could try weight sensing.

[Anonymous No.2431578]

>>2431279
Likely the pedal or cable. Inside pedal is a pot thats part of a voltage divider. If its shorted to ground or fully open it will go full bore or nothing.

[Anonymous No.2431581]

>>2431578
No, that was my first guess, but I completely disconnected the pedal, hooked up the torch switch, and it did the exact same thing. Something inside is fucked.

[Anonymous No.2431591]

>>2431466
Typical reflection spectrometry setups for hobbyists usually consist of a wide-band light source, a diffraction grating, and a camera sensor. I’d say that’s the most reliable somewhat cheap method.

[Anonymous No.2431598]

>>2431506
>>2431591
Just as I suspected, it might be doable, but no easy task.Thanks for the help anyway.

[Anonymous No.2431619]

>>2431150
>Take apart the meter and see what input jack it’s connected to, no way of telling just from description. If it’s a large fuse holder I’d suggest 22A, if it’s a small one then 220mA.

>>2431171
>If it's for an M205 fuse (20x5mm) then it's likely the low-end one. Same for those oddball 25mm long fuses, probably.

>Just unscrewing the clamshell to follow the thick trace is a better idea though.

>>2431172
>i already told you it's the 0.2A you need.
the only thing you need to determine is whether it's 1-inch long or 3/4-inch long.
so, measure the fuse holder.

So I did both methods. It’s the milliamp fuse. Thanks lads.

[Anonymous No.2431829]

What's the reason for this waveform that looks like AM modulation? It is supposed to be a simple tank circuit that makes a voltage divider in series with c3 to simulate an input antenna circuit. When I replace c3 with a resistor, it looks a lot better.

[Anonymous No.2431832]

>>2431829
wait, is it perhaps there is a second resonance which is a series resonance C3 + whatever reactance of C1L1?

[Anonymous No.2431859]

>>2431829
Probably? Could also be a beat frequency from resonant frequency mismatch, maybe. Short C3 and see if that changes anything. Or calculate the transfer function.

Also consider adding “startup” after your spice commands, it can often get the analysis stable more quickly.

[Anonymous No.2431868]

>>2431859
There shouldn't be any second resonance. The transfer function predicts a single resonance, and C3 is just a reactive voltage divider with C1L1. I ran an AC sweep and it shows a single resonance at 60Khz as expected. Once I remove C3 or change its value or replace it with a resistor I get an expected single sine wave. It's just a certain combination of values gives this "modulation". No idea.

[Anonymous No.2431894]

>>2431466
Use your nose and a lighter. Just burn a piece of it.
can also soak it and use 2 pads at fixed distance to measure hydro retention via resistance.

[Anonymous No.2431907]

>>2431466
Can't women instantly tell the difference by just looking at it?
Can an AI be trained to image recognition the difference?
AI perhaps compare using a camera and a zoomed in camera?
Can it be irradiated with some specific wavelength light-source to exaggerate the difference?

[Anonymous No.2431925]

>>2431907
>Can't women instantly tell the difference by just looking at it?

nope but a moth can.
use a stretch sensor to measure it's penile diameter as the fabric passes by.

[Anonymous No.2431926]

>>2431925
>nope
disagree

[Anonymous No.2431959]

is something wrong with pic related? Or do I need individual resistors for each button

[Anonymous No.2431961]

>>2431959
I will be using those buttons as an input for a MC if that matters

[Anonymous No.2431962]

>>2431959
You know the black wires on both sides are connected, right? Push a button, the pulldown resistor drops the full Vcc, and all three buttons appear pushed.

[Anonymous No.2431964]

>>2431962
Ah, I see it now. Sorry for the dumb question

[Anonymous No.2432022]

i am going to be making this microphone amp

Now of course in this shithole they don't have several of the parts i marked so i was wondering, can i just similar ones? like for example any power source than can output 15v and -15v should work right?

also someone suggested
>whilst I can see you are using basic filtering in the preamp stage I would suggest adding an R/C C/R EQ filter to roll off everything below 30 Hz and everything above 18 kHz as the capsule will struggle to reproduce anything outside of this frequency range however the preamp will still be wasting energy amplifying noise you can't hear.
how would that work if it was added to the schematic?

[Anonymous No.2432025]

>>2432022
for the op amp i would use this
and i found the tranny, but jesus fucking christ it's so expensive, can i really not use like one of those cheap ass 10 cents 2N trannies i have?

[Anonymous No.2432039]

>>2432022
The transistor has to be a JFET, you can probably get away with anything so long as the threshold voltage is approximately equal. The op-amp isn't an op-amp but a dedicated microphone preamplifier IC. Replace non-polar caps with film caps. Use capacitive multipliers on the voltage supply.

By changing the 22µF/3.9kΩ values you could get the desired high-pass cutoff, low-pass would need more components, but I really don't think they're necessary anyhow.

[Anonymous No.2432071]

>>2432039
the thing is the youtuber who made that schematic isn't ele engineer so the schematic works fine, but it's possible it can me optimized with cheaper parts and such.
SO theoretically if i google amplifier circuits for electret mics they should all work right? since the microphone basically just outputs tiny AC sine and i need to raise the amplitude voltage

[Anonymous No.2432097]

>>2432071
this one from great scott doesn't even use negative power supply and has the pass filters so it looks like a better solutin, none of those exotic components, just one opamp
and i can save money on analog to digital converter the original tutorial uses by plugging it directly into my sound card which already has ADC anyway
the only difference is the shitty little electrects there tutorials use have built in tranny while mine doesn't so i need to add that

[Anonymous No.2432105]

Is there a way to use the value of a resistor in plot expression? Something like this
R1*V(n002)/(V(n002)-V(n001)
doesn't work. R1 is undefined. I thought it would be pretty trivial to treat is as a constant and substitute the value.

[Anonymous No.2432106]

>>2432105
The question is about LTSpice

[Anonymous No.2432112]

>>2432105
I guess I can do it using .step param R
and {R}. But it is kind of ugly.

[Anonymous No.2432195]

How do I feed the output of an analog integrator at time t into a second analog integrator, if I'm only interested in the result of the first integrator at time t and not the signal before it settles?

[Anonymous No.2432197]

Is this the place where someone with minimal knowledge about electronics can ask a question about how to identify fix something (Laptop motherboard resistor(?) ) or should i try /qtddtot/ first?

TLDR, i tried to fix a dead motherboard by shorting something and while it works, i fixed it without knowing flux was a thing and i would like to replace the components i shorted for a "proper" fix.
Will post a pic in a hour or two.

[Anonymous No.2432211]

>>2432195
Not sure if I'm understanding correctly. An integrator adds up, so If you suddenly connect a signal into an integrator it the result will be 0 since it hasn't had time to integrate. Idk if that makes sense.
>>2431894
>>2431907
Yeah you could tell the difference by yourself but the idea is not to employ people or moths or burn the fabrics in the process. I'm thinking about measuring the charge as the fabric goes down the steel tube, synthetic materials should have a more negative charge, right? Although I suspect this will be highly dependent on humidity.

[Anonymous No.2432219]

>>2431466
>>2431490
>>2431598
Sew a NFC tag into the fabrics and toggle an electrically controlled damper in the chute to separate them.

[Anonymous No.2432238]

>>2432219
Hmm, maybe NFC would be too expensive, but resonators are cheap and waterproof. This seems a very viable option.

[Anonymous No.2432242]

>>2432238
>too expensive
https://www.amazon.com/NTAG215-NFC-Stickers-Guaranteed-Perfectly/dp/B071ZZTT6T
I don't know how they'll hold up through a wash and dry cycle, but they're pretty cheap.

[Anonymous No.2432249]

>>2432238
Measuring the dielectric permittivity by slamming each piece of fabric between capacitor plates would be somewhat easy, but you’d need to ensure that they’re flat.
The real question is, why are you combining two production lines only to seperate them again?

[Anonymous No.2432253]

>>2432249
>be me
>be intern
>boss sells "solutions"
>hospital ask boss to build a chute that separates reusable gowns from disposable ones
>boss says yes to anything, his "engineering team" will figure it out
>engineering team is 2 ppl + me
>intern asks on 4chan
Anyways thanks for your trouble

[Anonymous No.2432256]

>>2431466

Check them under UV. No guarantees, but one may fluoresce under ultraviolet (or one may fluoresce more strongly). A simple photodiode or phototransistor sensitive to UV would then be able to distinguish between them pretty easily with some very basic optics.

[Anonymous No.2432259]

>>2432253
NFC tags on/in the disposable gowns and nothing on the reusable gowns.
tag = 1 (on)
no tag = 0 (off)
Then charge Medicare $2000.

[Anonymous No.2432260]

>>2432253
It would've helped if you started with this instead of cryptic generic scenario. Weight will definitely be different on the reusable gowns so that's the easiest one to pick, just record all standard weights of reusable and toss the rest into the other chute. Reusable will also have a visibly different color. NFC tags are also an option, but you need special temperature and pressure resistant tags as the reusable shit goes through cleaning.

[Anonymous No.2432277]

I was some questions in a previous thread about wiring an inverter to my car. I ran into something else I would like an opinion on. I planned on using one of pic related add-a-circuit type fuse box adapters for ease of install, however all of the fuses in my car are lp-mini style and the thickest gauge wiring I can find an add-a-circuit device in is 16awg. I was recommended to use 12 or 10awg wiring for safety as the inverter may pull up to 25 continuous amps at max load.

Here are some details:
-300W inverter, so pulling 25 amps from 12V system in vehicle
-cigarette lighter outlet on my car recommends 120W max
-all the blade fuses in my car are LP mini style
-I want it to be wired so that the inverter can only be powered when the key is on (i.e. NOT directly to battery)

So it seems my options are:
-Use the cigarette lighter adapter, easiest and cheapest solution, maybe not safe, may blow fuse
-Use the add-a-circuit adapter and have a short length of wire that is a little smaller than recommended (preferred / easiest install for me)
-Use a 12V relay to power the inverter directly from the battery, kind of annoying to install, there's nowhere easy to get to to run a wire to the interior of my car

TL;DR: Is it safe to have a few inches of smaller gauge (16awg) wire powering something that may pull up to 25amps if the rest of the wiring is proper (12-10awg) gauge?

[Anonymous No.2432278]

>>2432253
Ah I see. Yeah, putting magnetostrictive tags on the reusable ones is probably a smart method. The only other method I can see being reliable is the diffraction-grating spectrometer, could even ditch the camera sensor and just mount photodiodes at particular angles from the grating, probably.

[Anonymous No.2432281]

>>2432277
Should be fine to have a short length of 16awg that then goes to 10/12. The voltage drop across it won’t be very high due to the short length, and the excess temperature of the wire shouldn’t be an issue either.

[Anonymous No.2432409]

>>2432281
>have a short length of 16awg that then goes to 10/12.

if it's stranded, then it's easier to just cut off stands until it fits.

[Anonymous No.2432413]

>>2432277
https://www.amazon.com/Copper-American-Gauge-Wire/dp/B0796JJHTQ
What's the model of your inverter?

[Anonymous No.2432414]

>>2432277
What is the actual power ratings of the device not the 300w advertised number. Look for like "12v 5a in 120v out" shit in little tiny writing on a tiny sticker somewhere. A real 300w inverter wouldn't even have come with a cigarette adapter.

[Anonymous No.2432444]

>>2432414
Oh is the 15A lighter socket limitation a universal thing? I did wonder about that a few threads ago when it was first brought up.
I suspect it’s 300W peak and 150W continuous, though I have seen 200W continuous inverters run of lighter sockets, probably due to the input voltage being above 12, but that’s still a bit too close to the fuse’s rating than ide be comfortable with.

[Anonymous No.2432568]

Is it possible to build an underground cable locator using some combination of coils and amps? I have two 20kV cables and one 230V cables in my backyard somewhere, and I'd like to find the general location of them, without paying for a fully featured cable locator.

[Anonymous No.2432578]

>>2432568
Yeah definitely, assuming they're not stupidly well shielded. You'll want to build a coil of the ideal shape to pick up the magnetic field lines emanating from a wire perpendicular to the ground, which I think means a toroid cut in half. A decent number of windings, an op-amp, a high-Q op-amp band-pass filter focussed on your mains frequency, and maybe some zeners in case you accidentally made a current transformer, and you should be able to find them.

[Anonymous No.2432590]

>>2432568
811 is usually free

[Anonymous No.2432593]

>>2432578
Cool, thanks!

>>2432590
I live in Sweden though. We have free maps available of where the cables are located, but I want to make sure they are correct before I dig into the ground.

[Anonymous No.2432594]

>>2432593
If you're 60hz mains you can get a dynatel 573a locator off ebay for $100.

They're pretty cheap.because they're old trash from Telcom but are built like tanks.

[Anonymous No.2432604]

Idk where to ask, so ...I signed myself up for a line following robot competition, hoping to gain some experience because the other guys are more experienced. Sadly too many people signed up and we split the teams and now its me, some guy who should be able to write the code, and a girl. I have never done a line follower robot, I only know the basics. What part should I focus on, and what should I optimize? Is the software the most important? Is arduino a suitable microprocessor for the job? Oh and should I bother with aerodynamic body?

[Anonymous No.2432614]

>>2432604
To be honest, and I've never even looked at line-following-robots before, I think the best thing to optimise will be feedback loop stability and fault-finding capability.
For the feedback loop stability, then some sort of PID loop handling the steering from the difference between the two sensors (assuming 2-sensor), and maybe also a simple PD loop to reduce vehicle speed when the line being followed is undulating too quickly, allowing it to speed up only in the straits. Honestly I'd do all of that in analogue hardware, but that's because I'm a prude.
For the fault-finding, in the event that no line can be found, the vehicle should drive backwards or even try to drive in the same path it got there from, until it spots the line.

An arduino should be fine (please use a nano instead of an uno), though if you want to keep a running list of past movements that might start to eat away too much RAM. If you want to drop the size, consider a custom PCB with an AVR soldered to it with an ICSP header.
Aero doesn't matter below like 10kph, even more so at smaller scales. You'd be better off designing it with a low centre-of-mass so it's hard to flip itself.

As for team assignments, you should take the time to throw out ideas and converge around a concept, and then ask each other what tasks each of you will want to take on. Let the more autistic people handle the deeper, narrower problems, while the least autistic handle the bigger picture, lateral problems.

[Anonymous No.2432621]

>>2432604
you should focus on looking up how other people do it and optimize for what parts you can get

[Anonymous No.2432648]

I ran a OPA2134 into output transformers and it works to drive headphones. pretty neat

[Anonymous No.2432656]

>>2432604
>What part should I focus on
I'd focus on the chick. Line following robuts are gay.

[Anonymous No.2432688]

Are there any solid-state relays or alternatives I can use for replacing the loud as fuck relays in pic related?
preferably a drop-in replacement and not costing an arm and a leg, It only needs to drive 12VDC/2A.
I got this small electronics module with the tow bar for my car to prevent my turn signals from blinking slower due to the extra load when a trailer is connected.
The problem is that I can't find anything about this specific problem and I'm not sure where to start looking.

[Anonymous No.2432731]

>>2432688
>drop-in replacement

those look unique.

>not costing an arm and a leg

at Aliexpress, they only charge fingers and toes

>only needs to drive 12VDC/2A.

that's easy to find if you're willing to manually wire them to the PCB.
(glue them in upside down, and run wires to the PCB)

[Anonymous No.2432736]

I want to employ a latching relay that is triggered by my microcontroller fuckery in order to protect the little 5v relays of aforementioned fuckery from current spikes.

What component could i add to my setup to check if there is current on a given device?
I assume my controller will be rebooted oftenly and i want it to know the states of the latching relays.

[Anonymous No.2432742]

>>2432736
forgot pic

[Anonymous No.2432745]

>>2432742
>over 9000 hours in fritzing later...
Did an elephant do that by squirting paint out of its ass?

[Anonymous No.2432749]

>>2432745
yes, how could you tell?

[Anonymous No.2432750]

>>2432742
>>2432745

pls excuse the crudity of my fellow poster but that drawing really is shit.
a proper drawing is supposed to describe functionality.
yours is essentially lines connecting to boxes, explaining virtually NOTHING.

anyway, one possible avenue of pursuit is: are there any power indicators (LEDs or lights) that light up on ''device''?
if so, one could use a photo-transistor to detect that, and create a logic signal from it.

[Anonymous No.2432753]

>>2432750
>pls excuse the crudity of my fellow poster but that drawing really is shit.
>a proper drawing is supposed to describe functionality.
>yours is essentially lines connecting to boxes, explaining virtually NOTHING.
i sincerely apologize

>>2432750
>anyway, one possible avenue of pursuit is: are there any power indicators (LEDs or lights) that light up on ''device''?
unfortunately no, i thought about branching a strong enough resistor between vcc (240VAC) and the device and reading the voltage after the resistor with the microcontroller (5vDC logic). Considering that its AC i think that wouldn't be applicable easily.

[Anonymous No.2432826]

Is there such a thing as an LED that emits in the NIR spectrum? I need a tiny heater lamp for an electronics project. Something I can power off a USB port.

[Anonymous No.2432857]

>>2432826
Does it have to be a lamp? Use a resistor or coil of nichrome wire.

[Anonymous No.2432874]

working on a brushless dc motor controller. i want to test it on the chink lab bench psu but i dont want to risk blowing it up, since i doubt it was engineered to withstand heavy inductive loads. what's the best way to do this?

the drive stage already has flyback diodes. i was thinking about a comparator on the motor controller's DC bus that just disconnects it above a certain threshold and dumps everything through a braking resistor. would this be adequate at protecting my power supply?

[Anonymous No.2432916]

>>2432688
If it’s just 12V DC and isolation doesn’t matter, just bodge in a few logic level MOSFETs. At 2A you wouldn’t even need heat-sinks for a halfway modern FET.

>>2432736
I don’t understand, why would you need to protect relays from current spikes? They’re connected to lights, so the load won’t make spikes at all, and even considering the alternator and starter motor I don’t think they’ll be damaged by the normal cold-cranking operation.

>>2432753
>240VAC
what the shit

>>2432826
Standard IR LEDs are 1000nm or so, which is really near IR (like a black body peak of 300K or so but much more narrowband). Not sure how high-power they go though, and with NIR there’s always the issue of eye damage, since it gets focused by your eyes’ optics onto your retina. Compare that to far/thermal IR, which is absorbed by the outer layer of your eye without focusing at all. People generally just use heat lamps (like ones for reptiles), but since you want it to be 10W you may be stuck with a handful of dinky little IR LEDs. If you can, I’d buy them in power packages (1W, piranha, etc), since the ones in 5mm and 3mm packages are usually not as brightness optimised.

>>2432874
Don’t run it off a bench PSU, at least not a linear one. Either get a fixed rail supply (24 or 48V or whatever) or run it off batteries.
Safety wise, you should figure out a way for your ESC to do a safe shutdown upon power disconnect, so just putting a fuse between your PSU and the ESC sends it into this state. In my case I’m having a 12V rail being buffered by supercaps so I can still switch the power FETs while the power is out for a while, maybe using regenerative braking through some zeners to keep them full. Not sure about resistive braking, I’ll just PWM the bottom-side FETs instead, since my FET heat-sink will be large.

[Anonymous No.2432927]

>>2432916
>In my case I’m having a 12V rail being buffered by supercaps
that's an interesting idea don't those have terrible ESR and current ripple rating -- wouldn't this severely decrease their lifespan?
>I’ll just PWM the bottom-side FETs instead, since my FET heat-sink will be large.
as in dead shorting the 3 motor phases to ground? i put my motor (250 watt hoverboard motor) in a vice and tried shorting the phases together. hard to turn even by hand, can't imagine how hard it would brake at rated operating speed.

[Anonymous No.2433039]

>>2432927
The intention is to use the supercaps with normal electrolytic caps and ceramics. The ESR of the supercaps will prevent them from eating high currents anyhow.
I’d put them on the 48V rail but that means like 20-30 of them, plus the switching regulator would eat up too much quiescent current, hence the zener idea.

Yeah as in dead-shorting them to ground. If you PWM this fast enough, these short spikes of high torque should be able to be made into smooth braking at a wide range of torques. You can also do this in-phase with motor rotation, such that you only get shorting between a given two phases when the potential difference is low.

[Anonymous No.2433053]

Does power factor correction essentially a resonant circuit? Say if you are lagging due to inductive load and add capacitors to correct the PF and if you get 1, haven't you just created resonance at the mains frequency?

[Anonymous No.2433056]

How does it work, does it only produce pulses or can it maintain 30kV at some feeble current? What are the uses for it anyway?

[Anonymous No.2433107]

>>2433053
>haven't you just created resonance at the mains frequency?

yeah, the inductor and capacitor start to trade current back and forth (like in 2 girls 1 cup) in resonance so that the overall line power becomes in phase despite neither of the 2 components being in phase.

[Anonymous No.2433171]

>>2433053
Well technically, aside from the common edge case of a purely resistive load. Power factor doesn’t make note of Q factor, I wouldn’t exactly call a Q factor of 0.01 “resonant”, even if it does have a faint bump at mains frequency on its bode plot.
Also don’t forget about nonlinear power factor, which basically everything besides simple inductive and capacitive loads give, since rectifiers draw at their peaks. PFC is fun to learn about, almost.

I always found it odd that by plugging a capacitor into a different outlet, you could cause less current to be drawn by your house if you have an induction motor running.

>>2433056
Looks like all the transformers are in parallel, which would be for high current carrying capacity if nothing else. Though considering the lack of an output rectifier and just a single transistor on the LV side, I’d guess that it’s just generating pulses. You may be able to time these pulses yourself by sending signals to the screw terminals.
Anything in the description? Part numbers visible in images?

[Anonymous No.2433203]

>>2432826
LEDs will probably feed more heat into their surroundings than incandescents with built-in reflectors, if your only desire is to make radiant heat. So I'd find an incandescent lamp with reflector that takes something under 10W when undervolted to 5V or so.

[Anonymous No.2433217]

I'm planning on a stereo audio mixer, to connect my console and pc to 1 output, which would be my Headphones. Would this diagram work? I'll be using a 12V power supply for all op amps. Will it be enough? And the most important question, would it sound reasonably good, or would it sound like shit?

[Anonymous No.2433218]

>>2433217
dunno why it's vertical

[Anonymous No.2433219]

>>2433217
>>2433218
horizontal here

[Anonymous No.2433223]

>>2431252
If you have a signal with only the interference, you could use an adaptive filter

Otherwise, a high order, high cutoff lowpass digital filter. The interference looks like it is significantly higher in frequency than the rest of the signal.

[Anonymous No.2433284]

>>2433217
>>2433219
Ok first of all, your op-amps are upside-down, operating with positive feedback instead of negative. Second, why the variable gain inverting amps at the start when you already have variable amplitude summing pots? Third, your op-amps won't work properly in a single-supply domain, since half of the signal is below the 0V rail. I'd instead aim to put your power supply on either side of the input signal.

I'd do pic related instead, possibly with inverting amps instead of unity buffers since I've heard they can be more stable. Isolation transformers may be necessary if the two sources don't like their grounds being commoned.

>imput

[Anonymous No.2433288]

>>2432211
>Yeah you could tell the difference by yourself but the idea is not to employ people or moths or burn the fabrics in the process. I'm thinking about measuring the charge as the fabric goes down the steel tube, synthetic materials should have a more negative charge, right? Although I suspect this will be highly dependent on humidity.
Under enough magnification, wouldn't the fibers look different?

Electrostatic cling also sounds like a good idea IF humidity is overcome & the cloth easily discharged.

[Anonymous No.2433291]

>>2433217
>>2433284
Note that the ground for the inputs and outputs must be that half-way in the middle of the 12V supply ground created at the bottom there. Also it's generally better to buffer that fake ground with another op-amp, means its caps can be a lot smaller.

Unless the OP was implying that he had a ±12V supply, idk.

>>2433288
>Electrostatic cling also sounds like a good idea IF humidity is overcome & the cloth easily discharged.
Isn't the problem that they're coming in BEFORE being washed? I don't think you could trust unwashed cloth to be triboelectrically consistent. In addition the requirement that it brushes up against some charge-inducer means that inducer is going to get coated in schmoo without very often cleaning, even a small amount would alter its ability to impart charge since it's the interface that matters. The optics of any optical method would also be prone to clouding, though that probably matters less for a spectrometry measurement since a tint can be normalised, as opposed to image-based recognition.

[Anonymous No.2433299]

>>2433291
>BEFORE being washed?
Ewwwww!!

[Anonymous No.2433316]

>>2433171
Almost nothing in the description, I think it's the same for each of the 50 different sellers
Only one LV board and one transformer for that price, of course.
Would it even tolerate being fired with an open circuit on the secondary side? Where's the energy gonna go, does it have a fixed resistor baked in across the secondary?

[Anonymous No.2433337]

>>2431252
If you do it in software, you could use a median filter.
Depending on the window size you choose, the median filter will almost completely preserve your original signal aside from lopping off the very tops of all peaks.

[Anonymous No.2433358]

>>2433217
that's not a very good schematic
try something like these

[Anonymous No.2433364]

>>2433171
>I wouldn’t exactly call a Q factor of 0.01 “resonant”,
That was my next question about possible voltage spikes at resonance Vin*Q. Is Q really that low? In my simulation I could easily make it 20-30 if R is relatively low with respect to L and C. What makes it so low in practice?

[Anonymous No.2433365]

>>2433358
What about the hummmm if sharing a GND return path?

[Anonymous No.2433370]

>>2433171
>plugging a capacitor into a different outlet
So that capacitor would be in parallel with the inductive load, a parallel resonance?
If R is low, It will significantly reduce input current but wouldn't it cause a huge current spike in your inductive load? Is that anything to worry about? On the other hand, if the active resistance is high, then you are not reducing current by much (probably due to low Q).

[Anonymous No.2433379]

>>2433370
I got pretty interesting results in simulation.
If L is low, then after adding C, current through R is reduced but there is a huge spike in current through L. However there is a point where adding a C only reduces current through R but the current through L remains almost the same, no spike! Pic related. I guess a typical inductive load is probably on the order of H so it is probably more realistic scenario than 1mH-10mH.

[Anonymous No.2433404]

Hi guys, i have made a small led circuit using 4x 3-3.3v micro leds, connected to a 9v battery and using a resistor suitable for up to 9v. Its working ok, but im wondering if it should be warm to touch? aslong as it doesnt get hotter and hotter its ok right?

[Anonymous No.2433409]

>>2433404
It's fine. Everything warms up when powered. Are the LEDs too bright?

[Anonymous No.2433492]

>>2433217
>>2433284
>>2433291
>>2433358

OP here, I made it based on these schematics. About the power, Its ±12V DC supply. The op-amp chip has 2 op-amps built in, each input module has 1 chip, and the final amp has another one.

>imput

yeah, it was already 3am for me bruh, and I'm not a native speaker.

Down here it's the schematic i used for the input module.

[Anonymous No.2433493]

>>2433492
And here it's the schematic i used for the final amp

[Anonymous No.2433511]

>>2433493
No pots to adjust volume of each channel independently? You don’t necessarily need it, especially not if you can conveniently adjust volume from both the devices you’re plugging into, but I’d like to put it on if it’s just two channels.

Also that op-amp circuit can go really high gain, so watch that you don’t fry your earphones with a +/-15V square wave, or your ears.

[Anonymous No.2433515]

I just wanna know if Megaman was marketed as Megamon in Jamaica. Can any Jamaicans confirm?

[Anonymous No.2433631]

>>2433316
>Where's the energy gonna go, does it have a fixed resistor baked in across the secondary?
Probably no resistor, I'd guess the voltage will just spike across its self-capacitance, then on the way back again it induces a reverse current in the primary winding, which goes through the MOSFET's body diode. Assuming the insulation can handle that spike.

>>2433364
Q generally won't be that high, because any inductive component will have reasonably significant ESR. Because at 60Hz, you need a pretty damn high inductance to get anything done, which means a lot of pretty thin windings.
Though to be clear, a Q of 0.01 was just an edge case to articulate my position on the term "resonant".

>>2433370
>>2433379
Is the R meant to be the ESR of the wiring? Ignoring that, if we assume that the voltage from the mains is constant and is the voltage across both the inductive and capacitive load, then the current through the inductive load won't change. Because the voltage across it won't change regardless of whether the cap is there or not. The presence of the capacitor just means that instead of going to and from the wall outlet, the current is just running back and forth between the L and C. Though it's different in a series circuit, where the voltage very definitely can climb up.

Also the correct AC amplitude is 120 * √2

[Anonymous No.2433699]

>>2433631
>Probably no resistor, I'd guess the voltage will just spike across its self-capacitance,
I assume the 30kV spec is just a ballpark value in that case

[Anonymous No.2433707]

>>2433365
sounds like the only earth ground is from the PC, shouldn't cause any problems unless something else is earthed
>>2433493
At least you switched to inverting mixer, that's a better schematic but still not very good. I would've gone with unity gain or fixed gain and volume pots on the inputs. Also for what it's worth I wouldn't drive headphones directly with a dual opamp. Especially not an 833 because I've had stability problems with those, but never 5532 or 2134.

[Anonymous No.2433712]

>>2433707
>earth ground
Sorry I meant GND as 0V, same applies for sharing +V and -V return paths.
Shared series resistance path, shared voltage drop cross-talk.

[Anonymous No.2433713]

>>2433631
>Is the R meant to be the ESR of the wiring?
Good point, I don't think it looks right. R should be in series with L and then C across RL.

>the current through the inductive load won't change
Take a look at the picture. I know it is a contrived example, but the top one is really interesting: without C the current is about 1A. But with C connected, current through R drops to 40 mA while current in L and C spikes up to 3A ! Not sure why.
But like I said, it is not even a realistic arrangement. The bottom one is the proper setup with R4 being the ESR of L2. Of course R can't be 100 ohm if L=100mH, plus I am not sure how to calculate the resonance frequency when you have an extra R in series with L. I will need to derive it.

[Anonymous No.2433829]

>>2433713
Resonance frequency I think is never dependant on resistive elements, at least not in relatively simple LCR circuits like that. The resonant frequency should still be the same. Ring it with a step function and see what it does.

The first one went down to only 40mA through the resistor because the current was just going back and forth between the L and C. I imagine that, without the C, the voltage drop across the R was enough that the L current was limited to 1A, but without the R it would be the full 3A, like it was with the C.

Pretty sure 100 ohm and 100mH isn’t impossible, in fact it’s quite possible for a somewhat small inductor. Though at mains it might melt with 3A through it.

[Anonymous No.2433865]

>ltspice still hasn't fixed font sizes changing between part orientations

[Anonymous No.2434016]

>>2433829
>I imagine that, without the C, the voltage drop across the R was enough that the L current was limited to 1A, but without the R it would be the full 3A, like it was with the C.
Yes. And also I can vary R from 0 to ~1k and all currents remain the same! 40mA through R and 3A through L and C. Amazing shit. But I don't know how to use AC KIrchoff analysis to predict these currents.

[Anonymous No.2434056]

I'm a terrible guitarist but an ok EE
is there anything I can do to stop me from coupling mains noise into my audio interface? I think there might just be something up with the guitar because it's done this at two different houses with two different audio interfaces. I don't know much about how electric guitars are wired, but I can do whatever you guys think will help it most.
Hell, I don't even know how it can be a grounding problem when the audio interface is a USB interface connected to a desktop that should be isolated from mains via the power supply

>>2433865
>ltspice still has the capacitor a different length than the inductor and resistor
chaps my ass 6 ways to sunday

[Anonymous No.2434083]

>>2433217
>>2433284
>>2433291
>>2433358
>>2433493
>>2433492
>Down here it's the schematic i used for the input module.
I meant up here.

>>2433511
>>2433707
>At least you switched to inverting mixer
HOLY SHIT, I was banging my head on the wall trying to understand what you meant by this, and then I noticed that I got the op amps in the wrong way on the diagram>>2433219 ;-; my fault. I intended to do an inverted mixer from the beginning. Now I fixed the diagram, and added volume pots at the end. I didn't add pots at first because there are volume pots in the input modules, but I added them at the end anyway.


Btw These diagrams >>2433492 >>2433493 are not mine, i got from a site.

And finally, this is the updated diagram.

[Anonymous No.2434123]

Why are these perfboards so common? They're so difficult to work with because you have to create solder bridges for every connection. It very easy to make mistakes and the mistakes are hard to fix.

It would make more sense for stripboards to be more common because they more closely match breadboards layout. These are much easier to work with.

[Anonymous No.2434141]

>>2434083
If it works it works. That's still not the best design but maybe I'm just a snob since I build mixers, preamps, and headphone amps for fun.
How did you make your pcb?

[Anonymous No.2434150]

>>2434141
I'm not an expert on the topic just curious. I searched and found some schematics on the internet, and build mine upon them. I I'm sincerely asking if mine is going to work, because I literally don't know it will work. It's my first schematic really, most of what I did up to this moment was simple solder jobs and repairs, nothing too crazy.

[Anonymous No.2434156]

>>2434016
That’s just the steady-state current amplitude, it’s independent of the resistance there during resonance. A high resistance just means it takes longer for energy to build up in the LC tank, but once it has the behaviour is the same.

>>2434056
Everything picks up mains noise just due to the wires being all around you. And that includes your body. You need to actively shield against it or use differential signalling to avoid it. You using humbuckers? Is your computer PSU actually isolated or is it grounded? Do you have a laptop to try it on, or some other way of isolating the USB interface?

>>2434123
It’s better to use thin solid core wire to make jumpers between legs, than to try and bead masses of solder into the right shapes.

[Anonymous No.2434159]

>>2434083
This circuit looks overly complicated. Instead of the 4 op amps and associated ciruitry on the left, you could replace them with either:

1) 4 audio isolation transformers.
2) 4 capacitive couplers
3) 4 resistors

Just keep the the pots that connect the initial stage to the final stage.

[Anonymous No.2434164]

>>2434159
The op-amps don’t even do the job of isolation transformers or AC-pass capacitors. The latter of which shouldn’t be necessary considering it’s probably a dual-supply circuit, but isolation transformers are kinda a good idea in general.

[Anonymous No.2434168]

>>2434150
It should work as is. Things that concern me are:
potentiometers in the feedback path, potentiometer directly on headphones, too much gain, too many opamps.

I don't think I would care if the output was inverted so I'd do it all with one opamp. You could also probably get away with only one volume control if you're doing like PC + console. PC would go straight into the mixer, the console would get a volume pot (on the mixer input) since it's less adjustable on its own.
Anyway check out https://sound-au.com/articles/audio-mixing.htm

[Anonymous No.2434193]

>>2429688
i bought a bunch of ams1117 fixed voltage LDOs from eBay for cheap. i've since learned that they're cheap chink clones and will probably blow up but i'm stubborn and want to use them even if it means spending more money on other protective circuitry.

i'm dropping 12V to 3.3V with these chink LDOs. i want to be sure that LDO failure doesn't pass 12V to my MCU. google tells me a crowbar circuit is a good idea, and maybe TVS protection diodes to protect against any transients that might somehow get through.

i've never used thyristors before. will basically any ~2A SMD triac work for this? i don't expect to draw more than 500 mA average from this LDO so i assume a 1A fast blow fuse and a ~3.6V trigger point would be adequate? and then any generic 3.3V standoff voltage TVS?

[Anonymous No.2434194]

>>2434193
>i'm dropping 12V to 3.3V with these chink LDOs
How big are your heatsinks?

[Anonymous No.2434198]

>>2434194
fairly decent, i guess we'll see. kek.

[Anonymous No.2434203]

>>2434123
smooth brain

[Anonymous No.2434234]

>>2434193
That TL431 circuit won’t work, the gate voltage of the SCR needs to get up to maybe 1V max before the gate current is enough to trigger it, and considering the TL431 doesn’t go below 2.5V, I think you’ll find it will never be off. Instead I think you may be able to use a PNP transistor with its BE junction in series with the TL431s current sinking path.
Furthermore, while fast-blow fuses are reasonably fast, you’d want to do the calculation to ensure that the 22μF cap is still providing the majority of that current, don’t want to damage your 1117. You may instead want to consider a latching MOSFET cutoff circuit instead of a crowbar+fuse.

Also you can use a linear regulator plus a pass transistor to handle higher currents, if you’re interested.

[Anonymous No.2434254]

>>2434203
cerebro suave

[Anonymous No.2434258]

>>2434234
that's a good point, i didn't consider that. by latching you mean with some sort of SR latch circuitry? if so, how would i power the latch IC? VS in my schematic is 12V. i can't just divide it down with resistors.

[Anonymous No.2434261]

>>2434258
>>2434234
would using the tlv431 help me out here? it can get down to about 1.25v.

[Anonymous No.2434263]

>>2434203
Please enlighten me, then. I never found any tutorials online on soldering these perfboards that doesn't involve creating ugly solder tracks with tons of solder.

[Anonymous No.2434264]

>>2434263
Not him but when I use those boards I only solder to the wire, like the bottom right of your pic.

[Anonymous No.2434265]

>>2434264
How would you solder something where you need to bridge multiple connections like an arduino?

[Anonymous No.2434266]

>>2434264
If you only solder to the wire, you should be using copperless perfboards anyway.

[Anonymous No.2434273]

>>2434265
connectors probably. idk I do analog only, I hate digital

[Anonymous No.2434293]

>>2434263

here's a better idea than what the other crumb said: place the wires on the component side.
- it helps you trace the circuit for errors without flipping the board 1 million times.
- it helps you avoid errors because you're used to counting pin numbers looking from the top of the chip.

[Anonymous No.2434444]

>>2434258
Latch could be anything from a dual NAND IC (74LVC2G00), a pair of transistors, maybe even just one additional transistor while the MOSFET acts as one. But most likely in this case, a comparator with positive feedback, as it also acts as the threshold detecting circuit for triggering the FET. Look at the commonly used "P-channel MOSFET power latch circuit", they're designed to be enabled by button and kept that way via MCU, but I'm pretty sure you could adopt that sort of circuit for your situation.

>>2434261
No, though as I said I think you can use a normal TL431 with a PNP transistor on it. Pic related. Pretty sure the pulldown resistor is necessary.

[Anonymous No.2434448]

anyone got a guide to making a vocoder that isnt in japanese?

[Anonymous No.2434476]

>>2429688
I want to buy a bang for the buck good station instead of my shitty chink solder. I saw in a second hand website atten858d for 115$~, and I was also searching my local store that officially imports Hakko and they sell fx888d for ~200$ or if I really want to be frugal an atten937a for ~120$. I assume heads are not included other than the basics, but I will probably buy a chiseled and beveled head.
Any tips of what types of heads I should get and what station should I eventually buy?

[Anonymous No.2434477]

Satan wants you

[Anonymous No.2434483]

>>2434476
>chiseled and beveled head

No reason to buy a fancy soldering station unless you're doing very detailed work.

[Anonymous No.2434500]

>>2434483
I guess you're right about that, but I want an affordable yet reliable station most importantly with adjustable temperature I won't have to replace for a few years

[Anonymous No.2434503]

>>2434476
get something with cartridge tips
get a chink station like the aixun t3a

[Anonymous No.2434548]

>>2434503
Not including shipping it costs the same as the fx888d and probably doesn't have warranty so I am not about that. Also how cartridge tips differ from normal solder tips?

[Anonymous No.2434573]

>>2434263
https://www.youtube.com/watch?v=i5MNLTc7YhY

[Anonymous No.2434835]

going back to my earlier question >>2432874

if i want to protect my power supply against inductive load experiments (motors) would pic related be adequate protection, assuming it's placed at the power input of my motor controller board? if negative current is sensed that means motor BEMF is necessarily greater than power supply EMF -- meaning that ALL i need to worry about is negative current across the pass transistor?

[Anonymous No.2434838]

>>2434835
i guess it would help if i attached the image. and the app note while i'm at it. https://www.ti.com/lit/an/snoaa23a/snoaa23a.pdf

[Anonymous No.2434850]

>>2434573
This guy is way better than many of the youtubers I've seen so far. But, even this youtuber made mistakes. The shakiness of his movements is greater than the width of the wires themselves and in some parts he struggles a bit to get solder onto the leads. One of the chips is also burnt on the edge.

The way the wires are packed together suggests he's using enameled wire, but I don't see him scuffing the ends of the wires. I don't see him using flux either, which is what I've seen from other youtubers when they solder SMCs.

I imagine him taking a lot of time to do the whole thing. But, I get the basic idea: use finely tipped soldering tip and magnifier.

I admire his dedication, but I still think it's easier to use boards with more convenient layouts.

[Anonymous No.2434876]

>>2434548
Yeah but it’s a 200W iron that can be used with legit JBC T245 tips. If you want something cheaper consider a Pinecil or T12 station of some variety.
Cartridge tips have the heater and thermocouple and tip all integrated into one replaceable piece, which means distinctly superior thermal performance. I wouldn’t spend a significant amount of money on a station that doesn’t use cartridge tips.
>warranty
If it breaks, you fix it yourself. Pinecil might have a warranty you can get behind, and it’s specs are pretty decent, plus it’s all open-source.

>>2434838
Those are good (they use P-chan FETs by the way), and the response speed should be acceptable, but if you want to build one yourself then getting that high-side-sensing comparator won’t be trivial. Plus your PSU almost certainly has an output diode anyhow. More importantly would be shunting voltage spikes that go above the PSU’s safe range.

[Anonymous No.2434888]

>>2434876
>getting that high-side-sensing comparator won’t be trivial.
can't you divide down both inputs to some reasonable common mode voltage? or am i missing something?

[Anonymous No.2434889]

>>2434888
It relies on minute differences between the inputs, so your voltage dividers would need to be made with sufficiently precise resistors.

[Anonymous No.2434896]

>>2434889
damn that's right. maybe i'll just put a big schottky diode across the front of the power supply, like 20A minimum and a few hundred volts. i don't trust the chink engineers who made this power supply.

[Anonymous No.2434952]

>>2434896
If you’re buying parts anyway, buy a TI ideal diode controller. They just work.

[Anonymous No.2434956]

Turns out that nobody makes toasters that use thermal infrared sensing to gauge how hot the toast is. At least not since the sunbeam radiant control toasters of the 50s and 60s that used a bimetallic strip. You can’t buy those where I live, so I figure I might as well chuck a PIR temperature sensor or two inside a regular toaster.

Though maybe the ideal toaster would be one that uses a spectrometer to look for the presence of molecules indicative of cooking bread, or to trigger it when the faintest hint of raw carbon is detected. Visible light spectrometry would be easiest, but something about an EFNMR toaster sounds kinda cool.

[Anonymous No.2434987]

>tl431 was actually tl432
good thing i tested for it

[Anonymous No.2435029]

GORILLA.BAS

[Anonymous No.2435126]

Here's my current design for a milliohm meter, using an instrumentation amplifier to move the floating measurement across to the CX102B panel meter. The panel meter runs on a +5V supply and accepts an input between 0V and 0.2V, so I've put it on a negative regulator in order to get its common-mode input range away from the rails.

I have a range switch to swap the amplifier's gain from 0.1 to 1, giving me ranges from both 20Ω and 2Ω. I figure my DMM probe contacts are too lossy to cover the 2-20Ω range properly. One side of the pole connects RV1/R2 to the other side of the amplifier, while the other pole switches the decimal place. The switch will be panel mounted, so I've represented it with a cluster of through-hole pads.

All the current sinks I was seeing were using the current sense resistors on a different side of the transistor to their load, and since the collector and emitter currents aren't quite equal, I decided I'd rather not have that. The PNP here is deliberate, should be more linear and easier to control. R15 might make the measurement more accurate, maybe.

I've managed to fit the entire thing on a single-sided board on the back of the panel meter, though some of those SMD components are so thick that I'll need to space the boards larger than a possible minimum.

[Anonymous No.2435130]

Oh it's not perfectly covering the back though, I needed extra room for these trimpots so they're going out on the edges.

For calibration, I'll first set the gain to 0.1 on the range switch and apply a known voltage across the voltage input terminals, adjusting the CX102B panel meter's own adjustment trimmer until it reads the same as my DMM. Then I'll adjust the reference voltage via RV2 until it reads 3V exactly, or rather until the current sink reads 100mA exactly. Then I'll swap the range switch to the other setting, adjusting the gain via RV1 until the known voltage is read correctly.

I think I'll also cram a battery clip in there so I can run it off a 9V, shouldn't be an issue. I'll use the switch on the DC socket to keep it unused normally.

Also please do not judge the routing around the D2PAK for grounding, it's the best I could do.

[Anonymous No.2435153]

>>2435126

i just googled ''op-amps'' and scrolled down several pages.
every single drawing has them pointed right, and the input and feedback resistors are all in drawn in 2 standard ways.
and every schematic has the signal flowing left to right.
but some fuckers just gotta be different. to make it harder to read and understand, i guess.
like those blacks who refuse to use standard english.

besides style horrors in this schematic, seems me there's a huge technical fault.
seems the probe is powered from 12V applied thru 30 ohms.
one of the main uses of a milli-ohmmeter is to detect shorted components on a PCB.
but if you're injecting 12V thru 30 ohms into various points, you're gonna kill components left and right.

[Anonymous No.2435169]

>>2435153
>every single drawing has them pointed right
Alright I amended that bit. I'm usually a stickler for that but that's just how this circuit developed.

>seems the probe is powered from 12V applied thru 30 ohms.
That 30Ω is the current sensing resistor, which now that I realise is not being sensed at the right position. Now that that's fixed, there should only ever be 100mA going through the load, and it should never see more voltage than what that would create in normal circumstances.

Though nasty things could happen when it goes open circuit, and when first clipping it on. Normally I'd want to chuck a diode or two across the current pins, but my 2-range method changes the gain of the amplifier instead of the current of the sink. At high-range, there could be up to 2V across it in standard operation. I guess I'll change that.

[Anonymous No.2435184]

Ok now it has a 100mA range and a 10mA range, corresponding to sense resistances of 270Ω and 270||30 = 27Ω. This should mean a reference voltage of 2.7V. A 1N4148WS diode is fine at the no-load condition of 100mA without overheating indefinitely.
The display is 2000-count, so the lowest current I'll care about is 10mA / 2000 = 5µA, while the 1N4148 diode shows 1µA at 275mV, which means I'll never see the diode interfering with my measurements. Though I can't say what the heat will do for it.

I wonder if an instrumentation amplifier is any more stable if I make the two stages have interfering gains (100 and 0.01, for example), because without the middle resistor it looks kinda bare.

[Anonymous No.2435192]

i have this motor with Rotary encoder.

What do the do A and C pins do?

[Anonymous No.2435202]

>>2435192
They tell you whether the motor is turning clockwise or counter-clockwise.

[Anonymous No.2435209]

>>2435202
thank you sir

[Anonymous No.2435217]

>>2435209
you're welcome

[Anonymous No.2435406]

I don't know if this is the right place to ask, but I'm trying to source a motor for a diy direct drive force feedback wheel for sim racing and have been offered this 3 phase Demag motor (pic related) for the low price of free by someone I know. I unfortunately am very confused by torque ratings and how to calculate them. I am looking for a motor with a holding torque of at least ~2.4 newton meters, but it would ideally be around 10nm (this is based on what a lot of high end dd sim wheels are rated for even though most of them don't actually operate near that). I used this online calculator (https://www.electrical4u.net/calculator/electric-motor-torque-calculation-formula-torque-calculator-online/)) to get a value of 6.20nm. Does this seem like a reasonable value based on the specs and could anyone tell me what type of torque this is for?

[Anonymous No.2435408]

>>2435406
Out of curiosity how are you going to run a 230/480v three phase motor as part of a sim wheel?

[Anonymous No.2435420]

>>2435408
I'm honestly just planning to install a rotary encoder on it to make a ghetto servo and copy this guy's build (https://www.youtube.com/watch?v=hHY1PyycJ5s).). He uses a 40v power supply and some open source VFD board and driver that I don't quite understand because I haven't looked at the documentation yet. I'm thinking I'm in over my head with this and should just use a servo or stepper with a known torque rating. The only reason I am considering this motor is that the Mige 80st's and 130st's that people who've built these before recommend have doubled in price due to shipping.

[Anonymous No.2435447]

>>2435406
Not sure about torque readings, but at 0.25hp it should be powerful enough.

>>2435408
You'll need a 3-phase variable frequency drive. They're not exactly cheap, in fact you may find it's cheaper to buy a 6-12S BLDC + ESC, or a stepper + driver.

[Anonymous No.2435504]

Rumor has it that Bennick Honks burned off his pinky toe with a bluray laser stuffed in an altoids tin. Get well soon, Bennick. You don't really need your pinky toe anyway.

[Anonymous No.2435586]

>>2435504
His GF has confirmed that the ''pinky toe'' story is a cover-up to avoid further embarrassment. It's actually his ''pinky joe'' which is the injured member.

[Anonymous No.2435588]

Are there any JLC equivalents for flex PCBs? I.e. cheap

[Anonymous No.2435591]

>>2435588
PCBway is the only place I've seen that does them at all, doubt you'll find them being done for cheap. That's why I'm buying some kapton tape and copper foil to stick together and make my own flex PCBs via etching.

[Anonymous No.2435593]

>>2435586
>''pinky joe''
He said that was from spilling hot cheese curds in his lap at Culver's drive through. The skin grafts should be mostly healed by now but Menards ran out of electronics because Bennick bought all of them so no new videos until June 2025.

[Anonymous No.2435673]

>>2429688
I want to make a battery powered wireless device to blow firecrackers from a safe distance.
I want all the control circuitry in a box away from the firecracker and two wires going to the actual area where the blast would take place and the firecracker is propped up.
Now the question is, should i make it arc based or coil heating based.

[Anonymous No.2435682]

>>2435673
Explosive wire method!

[Anonymous No.2435685]

>>2435682
>Explosive wire method!
Sadly not reusable

[Anonymous No.2435747]

>>2435673
Use a friggin burny laser beam.

[Anonymous No.2435803]

>>2435673
>firecrackers

[Anonymous No.2435939]

posted a while back about PWMs. i want to use one to control the speed of a motor. the problem is, PWMs fail closed. i'd be okay with the motor shutting itself off, since i'll usually be operating it at low speeds for several days unattended.
however, i really do not want the PWM to fail and then the motor stays on at max speed, which could be catastrophic.

if i use the output of the PWM to control a normally-closed relay, and i just operate the PWM "opposite" to how it's labeled, would that work how i want it to?
so, what was normally "10% speed" is now "90% speed, since instead of closing the relay for 10% of the time, it now opens the relay for 10% of the time.
but, most importantly, if the PWM mofset shorts itself, now it will keep the relay held open constantly, so the motor stops.

does that make sense?

[Anonymous No.2435948]

>>2435939
Yes, but what if relay fails short, because that's very likely to happen if you switch it constantly with PWM. Relays are good for switching signals once per few seconds, feeding PWM to it will degrade your contacts really fast and can cause them to stick.

Just use digital microcontroller based solution because it will be the safest and most reliable (noise, voltage glitches, component aging, tolerances...).

[Anonymous No.2435953]

>>2435948
i don't really know much about microcontrollers but i'll look into it. solid state relays are definitely a better option and i'm sure there is a very simple way to do exactly what i want to do, i just don't know how.

[Anonymous No.2435965]

I asked on /k/ but I guess here is a likely better place to ask

Is there a formula or other way to calculate how many hours a portable battery would last when powering a mobile ham radio?

I know the Ah of a particular battery, and I know how many amps the radio itself draws in order to even operate, but I don't know how to calculate exactly how many amp hours are consumed per, say, minute of radio transmission at a given power.

I know the obvious answer is just to get the biggest battery I can afford and use the lowest output power I can get away with, but I still wanna have an idea of "I can talk for approximately X hours, or talk and receive for 3X hours"

[Anonymous No.2435966]

>>2435953
The simplest way is probably just using a fuse. Measure normal operating current and then measure current at 100%. Then just find a fuse that trips at some current below 100% in acceptable time. You will lose some pwm range though.

[Anonymous No.2435969]

>>2435965
the power draw will vary based on multiple factors. you could imagine that if you had the volume turned up to maximum, that would take more energy than if you had the volume very low.
one way you could check is literally just putting batteries in it, leaving it on, and checking it periodically until it dies. then you compare that to the rating of the battery and you can determine your actual power draw in the way that you actually use it.

[Anonymous No.2435970]

>>2435953
>it will keep the relay held open constantly, so the motor stops.

if you're willing to take a deep dive into industrial timers, i think you'll find a way to get one to shut off your motor if it stops getting PWM pulses.
something akin to this Omron part would probably do the job if you set up it like a missing-pulse detector.
of course, Omron doesnt give these away for nothing, so next step might be to find a chink alternative.

[Anonymous No.2435974]

>>2435965
Start with your radio specifications. For example
>Yaesu FT-2980R
>Transceiver Input Voltage: 13.8 Vdc
>Transceiver Maximum Current: 17.0 A
>Max. RF output power: 80W
To transmit 80W of RF into the air you need P = Input voltage X Max. current = 13.8V * 17A = 235W. From this we can calculate amplifier efficiency which is eff = transmitted power / input power = 80W / 235W = 34%. This might change slightly if you transmit at different power levels but it should be in the right ballpark.

Now you can calculate how long your setup will last by first converting your battery capacity to watt-hours by multiplying battery capacity with battery voltage. This is again an approximation because battery voltage is not constant but will drop with time. To get approximate operating time you can then

Operating time = Battery capacity [W.h] / RF output power [W] * Transmission efficiency [%]/100

Let's use small 40Ah car battery (12.8V) which has capacity of approx. 512 Wh. Let's set output power to 20W.

Operating time = 512 Wh / 20W * 34%/100 = 8.7h

at 20 W you could thus shitpost for about 8 hours with that battery.

[Anonymous No.2436067]

>>2435974
Mine is specifically a chinkfeng uv25x2 so on high power that's a pretty good estimation for me, thanks

To calculate my transmit amperage i'd take the watts divided by the voltage, but do I use the 13.8v power supply voltage or its 7.8v operating voltage?

[Anonymous No.2436107]

How viable are these fellows for "hacking" into a variable supply?

[Anonymous No.2436114]

>>2436107
What are they? Left looks like a battery-to-5V USB boost circuit, I guess the right one is the same?
Assuming they run off the battery voltage and not off the bootstrapped output voltage, there's probably plenty of room to change the boost voltage as far as the integrated switch can handle it, and all the way down to the supply voltage too. If that assumption is incorrect though who knows. Find the datasheet for the ICs, if it's labelled.

Either way they're just shitty fixed-frequency integrated-switch jobbies that may have built-in shutdown at low-load condition. Be better off starting with an adjustable ebay switcher module.

[Anonymous No.2436116]

>>2436107
Look up the IC datasheet and find the feedback (FB) pin. Modify the resistor divider circuit to output the desired voltage (within spec of the ICs capability). Ask Jeeves "voltage divider calculator".

[Anonymous No.2436118]

>>2436114
They're cigarette lighter adapters i.e.12V to 5V buck converter.

[Anonymous No.2436146]

>>2436118
>cigarette lighter adapters
Ah that explains the funky spring contacts.
>buck
They're often a pain to set to lower voltages, since they use a voltage divider to step the output voltage down to some reference level. Say, 1.5V. So whatever you do, the lowest voltage it can possibly output by changing that voltage divider is that 1.5V. Even worse if it's a dedicated IC that uses 5V as its reference, as that way it doesn't even need a divider.
You'd have to use an amplifying circuit of some sort.

Trace the circuit.

[Anonymous No.2436153]

>>2436146
Anon asked if he could modify them into a variable supply. It's possible to do that by replacing a resistor in the divider with a potentiometer, but output power will be low (500mA-1A) without further modification.

[Anonymous No.2436192]

I have a laptop that I think is leaking current from somewhere
Is it possible to try to locate the source of this leaking current or am I basically going to have to apart and put every component I can back in place and hope for the best?

[Anonymous No.2436196]

>>2436192
>leaking current
You need a plumber.

[Anonymous No.2436200]

>>2436192
>>2436192
You mean the battery is discharging quicker than it should? Either take the battery out and wire it up to a benchtop PSU and/or variable load so you can see how well it keeps a charge, or measure drain current by putting an ammeter in series with the battery as it runs, to see if it matches up with the Ah capacity value of the battery.

[Anonymous No.2436203]

>>2436200
No I mean when I touch the case I get electric shocks
It was like that for years and I ignored it but now the computer doesn't boot anymore
When I plug it in and turn it on it still shocks me

[Anonymous No.2436224]

>>2436203
2-prong or 3-prong power brick?

[Anonymous No.2436225]

>>2436224
3-prong
Australian standards
Laptop is a thinkpad t420

[Anonymous No.2436234]

>>2436225
Then it's surprising that there isn't sufficient grounding to keep the shocking down. Are they static shocks, or are they more like a buzzing?

[Anonymous No.2436241]

>>2436234
It's like continuous tingling

[Anonymous No.2436243]

I'm going to wrap a flat power cable around a MAG welders gas hose but I'm wondering if the cable acts like a coil and causes more electromagnetic problems to surrounding electronics than a straight cable would. Flat cable makes the combination of the cables and the gas hose more flexible than the straight cable. I'm building an external wire feeding box for a stick welder and need a MAG cable.

[Anonymous No.2436244]

>>2436241
>It's like continuous tingling

i got a laptop power brick that puts out 60Vac and zaps me occasionally.
nothing serious, but annoying. (in fact i miss this tingling interaction sometimes)
most likely it has a leaky Y cap.
Y caps are connected directly between the live wire, and the ground on the output.
if the brick is grounded, then this stray current should be sucked up by the ground wire.
so, presumably your ground is not connected properly at the socket, or fuse box, or power cord.
but even so, a replacement power brick should be acquired with all urgency.
(except if it has already killed the laptop, in which case it's all trash now)

[Anonymous No.2436246]

>>2436243
>I'm wondering if the cable acts like a coil and causes more electromagnetic problems to surrounding electronics

pls stop wondering about such silly stuff.
it ruins your weekends.
not 1 chance in a trillion it will make any difference.

[Anonymous No.2436247]

>>2436246
I mean technically he's got a few hundred amp turns going on there

[Anonymous No.2436248]

>>2436244
Well here's the thing
I have two laptops and two chargers
Laptop still shocks me when using both chargers while using both charges on the other laptop (both thinkpads) doesn't buzz me
That's why I thought it could be current leakage, something in the case is touching something it shouldn't but then idk how to find what that is

[Anonymous No.2436250]

>>2436248
>something in the case is touching something it shouldn't

doesnt seem likely.
laptops work at 16-19 volts DC which is not gonna shock you unless you touch your tongue to it.
if it uses CCFL lamps for the LCD display (i.e. not an LED backlight) then it'll have a transformers generating around 800Vac or more.
if that was shorted to the case, i can see a possibility of shocks.

[Anonymous No.2436253]

>>2436248
>something in the case is touching something it shouldn't

doesnt seem likely.
laptops work at 16-19 volts DC which is not gonna shock you unless you touch your tongue to it.
if it uses CCFL lamps for the LCD display (i.e. not an LED backlight) then it'll have a transformers generating around 800Vac or more.
if that was shorted to the case, i can see a possibility of shocks.
one way to test it is if shocks you when the LCD is lit, but not when it goes to sleep.

[Anonymous No.2436261]

>>2436246
More than a harm to surrounding electronics, I'm afraid that the wire acts like an electromagnet and shakes the torch handle while welding or makes the sparks fly to unexpected direction or something. May sound schizophrenic but could happen and ruin the welding.
>>2436247
There's like max 250 amps and 12 turns on the gas hose which is 1/2" outer diameter. The flat cable consists of several bunches of thinner copper strings so they could be placed evenly around the gas hose like a rifling but that effects the flexibility of the combination and could still act as an electromagnet.

Inside the gas hose is the welding wire housing that could act as a core of an electromagnet and in the worst case, it could somehow disturb the droplets dropping rightly to the weld.

[Anonymous No.2436279]

>>2436261
Pretty sure the magnetic force won't be significant enough to cause vibrations. I suspect the only issue would be eddy-currents when AC welding.
>makes the sparks fly to unexpected direction or something
Don't think he'd get that either since the windings won't be near the tip, but it does make me wonder if putting a solenoid around your cup could help elongate the shielded area.

[Anonymous No.2436373]

>>2429688
How to get 12V from FireWire ?

[Anonymous No.2436385]

>>2436373
Connect the power leads to a buck converter set to 12V.

[Anonymous No.2436387]

>>2436385
>Typically a device can pull about 7 to 8 watts from the port; however, the voltage varies significantly from different devices. Voltage is specified as unregulated and should nominally be about 25 volts (range 24 to 30). Apple’s implementation on laptops is typically related to battery power and can be as low as 9 V.
https://forwardtechnologies.com/1394what/

[Anonymous No.2436392]

>>2436387
so they're saying laptops shouldn't output more than 12v?

[Anonymous No.2436422]

>>2436392
I think it says that firewire ports on old Apple laptops put out max 9V, but that was 20 years ago. Expect 24-30V at up to 45W output from a newer firewire 800 port.

[Anonymous No.2436423]

Hello. Can I use a normal usb to rs232 adapter like picrel to program MCUs?

[Anonymous No.2436434]

>>2436423
https://www.youtube.com/watch?v=P5LCPMqwhLI

[Anonymous No.2436486]

>>2436279
>putting a solenoid around your cup
Putting a permanent magnet around the cup could be nice if it prevents sparks flying on you while welding upwards under a car. Unfortunately glowing steel doesn't even stick to magnet so maybe there's no problem at first place and not a solution in the other.

[Anonymous No.2436537]

>>2436434
Very helpful. Thanks a lot anon

[Anonymous No.2436577]

>>2436537
no-
thank (You)

[Anonymous No.2436598]

>>2436423
>rs232 adapter like picrel

impossible to say.
a lot of serial equipment takes design shortcuts, or doesn't implement all the usual pins.
example: once connected a computer that only put out +12V (no -12V) to a modem that could only detect negative voltages.
try it and hope for the best.

[Anonymous No.2436634]

>>2436423
depends, we use them to get online with old plcs just fine.
I recommend the Tripp-Lite Keyspan USA-19HS
It has really good compatibility across the board

[Anonymous No.2436668]

>>2436423
You’ll need to level-shift it back down to 5V or 3.3V logic to talk directly to an MCU, you’re better off buying a cheap USB-to-TTL converter, preferably one with a switch or jumper to swap voltage levels.

>>2436486
I was thinking more to direct the arc than to direct the molten metal.

>>2436598
That’s absolutely not compliant with the RS232 spec, sure it wasn’t faulty? I know I’ve done that once or twice myself, but that was specifically when I knew what RS232 transceiver I was interfacing with so it wasn’t an issue. Maybe the transceiver here was designed to be used with just one specific peripheral?

[Anonymous No.2436675]

>>2436668
>Maybe the transceiver here was designed to be used with just one specific peripheral?

nope.
both units took design shortcuts but which would still work if the OTHER unit was 100% compliant with serial specs.

[Anonymous No.2436724]

>>2436107
Traced the one on the right.

[Anonymous No.2436743]

>>2436724
Not sure what that B201 is, but I'm pretty sure it isn't a 200Ω resistor, as that would make the feedback reference stupidly low. Assuming the feedback divider is 12k/1.5k, that makes a reference voltage of 0.58V, which is sensible. So you'd fairly easily be able to tune the output voltage anywhere from 0.6V to 5V, and probably up to 12V too without much complaint from the IC. Just remove R3 and R4 and replace with a 10k potentiometer.
But those two RC networks may not be ideal at arbitrary output voltages and load conditions, so it's possible you'll end up with instability.

[Anonymous No.2436763]

yikes

[Anonymous No.2436800]

>>2436763
I blame the BLTs.

[Anonymous No.2436834]

Hello gentlemen, what are the go-to solutions for interfacing a 3x4 or 4x4 keyboard with an arduino ? I am trying to make a project and I have run out of pins. I tried looking for a shift register solution but i cannot find anything that works.

[Anonymous No.2436837]

>>2436834
4x4 matrix that uses 8 pins is the standard. If you need to use less than 8 pins then either a resistor ladder going to an ADC, or as you say a something using external multiplexing ICs. With only 4x4 using full shift registers is a bit overkill, instead for addressing you may want to use a 1-of-4 / 2-to-4 decoder. You could then use a priority encoder to turn that back to a 2-wire signal, but if you want any rollover at all you’d be better off with a parallel-to-serial shift register.
The actual arrangement of the matrix is fairly simple, pic related. Write to the rows, read from the columns. If the output is more conventionally active high (0100 instead of 1011) you’d need to swap the pull-up resistors for pull-downs. The diodes aren’t necessary, but without them you won’t be able to get reliable rollover, so it’s up to you whether you want them.

[Anonymous No.2436840]

>>2436837
>resistor ladder going to an ADC
I thought these were a meme. Are they a widely accepted solution ? Guess I will make one of these first and then see where to go from there.

[Anonymous No.2436844]

>>2436840
>I thought these were a meme
They suck for conversion time, which is especially annoying if you have other time-sensitive stuff going on. Should chuck the "conversion finished" interrupt and ensure your ISP can handle that happening at the right instances. That or count clock cycles and get your result just in time.
IIRC they're used for steering wheel buttons so you don't need as many slip rings.

[Anonymous No.2436947]

>>2436668
Yes. I'll buy a proper converter indended for MCUs then. Thanks

[Anonymous No.2436974]

i need a buck converter IC that will drop 10-30V input down to 9V at anywhere between 0.1 and 1.5A. noise isn't super important as i plan on filtering the output with an LDO. TI simple switcher ICs look great but the parts shortage makes them pretty much unobtainable. i have some chink UC3843 and UC3845 ICs that i bought. worth trying to use these or is it the wrong tool for the job?

[Anonymous No.2436976]

>>2436974
Mini360 takes up to 24V input. XL4005 or XL4015 would do the trick.

[Anonymous No.2436978]

>>2436976
>Mini360
CX8509

[Anonymous No.2436982]

>>2436976
>XL4005
forgot about these. i think i might actually have some of these modules in my parts box. just need to buy the bare ICs (need the dc-dc converter to be on my own PCB.)

[Anonymous No.2436986]

>>2436982
They cost around 50 cents per piece from the slow boat, $2 per piece from the USA.

XL4005E1 TO-263

[Anonymous No.2436988]

>>2436986
can aliexpress be trusted or is it a case of chinks counterfeiting chinks i.e. i should just bite the bullet and order from LCSC?

[Anonymous No.2436989]

>>2436988
I'd order from LCSC before aliexpress, but that's your decision to make.

[Anonymous No.2436995]

I have an ATtiny and a bunch of 7 segment displays. I would like to build a clock with a stop watch function, perhaps a few other gimmicks, if possible.
But I have no clue how to proceed. Where do I even begin?

[Anonymous No.2437007]

>>2436995
Do the search engine shuffle for "attiny clock stopwatch" and copy somebody's circuit, or read the 7-thousand page datasheet for the attiny series you want to program.

[Anonymous No.2437009]

>>2436995
>Where do I even begin?
At the beginning.

[Anonymous No.2437011]

>>2437009
Let there be light?

[Anonymous No.2437014]

>>2437011

[Anonymous No.2437082]

>>2437014

[Anonymous No.2437089]

Working on a ATtiny-based Wang computer called TinyWang.

[Anonymous No.2437351]

>>2436995
With an RTC and some sort of multiplexing method. I’ll assume you’re using 6 digits, which means traditional 7-seg-decoder + 1-of-N decoder multiplexing will take 6 of your pins. If you’ve got a 14-pin or greater MCU that’s no issue, if you’ve got an 8-pin MCU then you’re fucked, and will have to shit out all your data via shift registers. A pair of 595s would do the trick and take only 3 or 4 pins, but also takes a bunch more progmem to work. And probably needs some buffering transistors, but that applies to the decoder as well. Then it’s an RTC module of some sort, no clue how they work but they probably only need a couple of pins. Then some buttons, use resistor ladders if you’re running out of pins. The rest is programming hell, for which you’d better be optimising RAM by addressing registers directly without using juan’s arduino library.

[Anonymous No.2437408]

what size capacitor should i use for a dc motor that draws two amps at 3V? i want to make sure it wont pull down my power rails and fuck up the micros power supply

[Anonymous No.2437423]

>>2437408
>what size capacitor

take the number of amps and multiply by 1000uF.
optionally, double it for peace of mind.
then double it again to account for start-up inrush current.

[Anonymous No.2437429]

>>2437351
I... don't know if I'm ready for that.
But I'll put it on my todo list

[Anonymous No.2437465]

>>2437408
What’s the DC resistance? From that you can calculate stall current. Even better, figure out a current-time curve. Then using I = C*dV/dT you can calculate what the ripple voltage will be for a given capacitance. Use a scope or arduino ADC or whatever to record this current-time curve.

[Anonymous No.2437480]

Does anyone know anywhere selling really tiny DPST rocker switches? i have a few SPST which are panel cut 12 x 8 mm but every DPST the smallest it can find is 19 x 13 mm which is too large. anyone have a source for 12 x 8 size?

[Anonymous No.2437515]

Can a power audio amplifier be repurposed as a transmitter as is, by replacing the speaker output with an antenna output, perhaps with some impedance matching circuitry?

[Anonymous No.2437518]

>>2437515
Dunno.
https://github.com/F5OEO/rpitx

[Anonymous No.2437523]

>>2437518
VHF transmitter with ATtiny:
https://github.com/cnlohr/avr_vhf

[Anonymous No.2437525]

>>2437518
>>2437523
how the fuck do you generate output power on a GPIO pin without any special circuity?? is it a DAC output? at like 10mA max?

[Anonymous No.2437529]

>>2437523
also
>VHF
>attiny
doesn't it run at 8Mhz max?

[Anonymous No.2437532]

>>2437525
It's PWM output, so low power and needs filtering.
>>2437529
Running at 5V and overclocked. Also PWM output.

[Anonymous No.2437533]

>>2437532
i just looked it up and one of the projects mentions modulating the PLL frequency which is much higher that than the CPU clock. that's clever.

[Anonymous No.2437537]

>>2437529
>doesn't it run at 8Mhz max?

square waves have harmonics into terahertz.

[Anonymous No.2437557]

>>2437532
>>2437537
I don't get it. Does it broadcast PWM? Or PWM gets filtered into sine? The description says there is no external components. So the PLL pin outputs PWM into the air and that's it?

[Anonymous No.2437566]

>>2437557
Or is it just broadcasting a bunch of harmonics and hopefully some of them are the right ones and the filtering job will be done by the receiver's tuner? That would be bad news if you add a power amplifier and broadcast over a long range and get caught.

[Anonymous No.2437567]

>>2437557
It broadcasts a NTSC signal over VHF by PWM of two asymmetric antennas. The ATtiny is overclocked to 60MHz and the output power is very low (cigarette lighter socket FM transmitter for old car radios lacking an external audio input power levels).

[Anonymous No.2437568]

>>2437566
Yeah, if you want more Tx power you need to filter the signal.

[Anonymous No.2437571]

>>2437537
>terahertz
but probably only a couple of harmonics have enough magnitude. so i am guessing if you want to broadcast FM radio and your PLL can't output full 100Mhz you can set it around 33Mhz and rely on the 3rd harmonic?

[Anonymous No.2437578]

Im also new to electronics, mostly getting into it as a side hobby.

Rn lm trying to change the min and max on a hair straightener. Is there a way to do it or factory setting are the only way to keep it?

[Anonymous No.2437580]

>>2437571
Did you watch the video?
https://www.youtube.com/watch?v=DJyQi0aUqVQ

[Anonymous No.2437583]

>>2437578
>Is there a way
impossible I tell you

[Anonymous No.2437588]

>>2437583are you saying its 100% impossible or with my current understanding its impossible

[Anonymous No.2437589]

>>2437588
Look at the way it's done with cheap soldering irons and adapt that to suit your pube-straightening needs. What's the power rating of your hair thing? Should be labeled on the mains plug.

[Anonymous No.2437592]

>>2437588
Maybe you could install a dimmer switch wired to the GFCI outlet and plug the hair thing into that. The real limiting factor is the heating element's maximum power rating.

[Anonymous No.2437596]

>>2437592
AC mains > GFCI > dimmer switch > pubic coiffeur

[Anonymous No.2437636]

Where do you guys find stuff to repair? Other than eBay. I don't wanna spend a fortune just from the "I know what I got" crowd.

[Anonymous No.2437639]

>>2437636
Save big money at Muhnards.
https://www.youtube.com/watch?v=dxKXkXlYlls

[Anonymous No.2437693]

>>2429688
Is there any money in doing circuit / pcb design ?

[Anonymous No.2437716]

>>2437693
no

[Anonymous No.2437723]

what is the name of this thing? not talking about the entire device, just the light blue part where you insert your ICs

[Anonymous No.2437724]

>>2437693
the biggest hurdle is assembling slave labor
second is deploying spies to steal people's ideas
>>2437723
ZIF socket (zero insertion force)

[Anonymous No.2437781]

>>2437693
If you have the qualifications and experience to get hired by an EE firm/department then sure.
If you’re self-taught, then you’re not going to have much luck. I can only suggest you learn 3D modelling and printing so you can design and make entire prototype “products”, and sell yourself on Fiverr or wherever. With any luck you get picked up by a kickstarter that goes successful and you can ride that up. More likely you just get a few jobs here and there. Build up a portfolio of professional looking past projects to give confidence to prospective customers or employers. After long enough you may be able to make some contacts and get hired without a qualification. No promises though.
You could also try your own crowdfunding attempt, but that’s even riskier, and you’ll need to ensure that you’re a part of a trustworthy and competent team. Avoid grifters.

[Anonymous No.2437791]

>>2437693
sell boutique guitar pedals

[Anonymous No.2437830]

why PCB printing companies are so jew

[Anonymous No.2437852]

These things are amazing, I wish they were double sided so you can soldrr on both sides

[Anonymous No.2437913]

>>2437791
This is what I call the "etsy route". Make something and get lucky enough that members of a somewhat obscure hobby that's been starved for content will pay a premium for it. Particularly for hobbies that are full of people with disposable income. But the guitar pedal market has been saturated with chinese clones of the classic effects for a while now, so you'd need to bring something particularly novel to the playing field, and even then it would get copied by the chinks within a year or two. Plus guitar guys are usually guys in their 20s so don't have massive amounts of money to throw away.

Plug-and-play garden-monitoring electronics are a decent idea, or anything else that brings down the required mental/temporal investment for home automation.

But like 80% of anything is going to be the mechanical design, making something solid and durable, the circuitry inside will be pretty straightforward in comparison to the form and material selection and manufacturing method.

>>2437830
Which ones, the Chinese ones or the not Chinese ones?

>>2437852
That brown FR2 is kinda shitty because of how easy it is to delaminate, so regardless of whether it's 2-sided I think upgrading to FR4 protoboard should be a priority. 2-sided has the disadvantage that it takes a lot more heat to make a joint, and joints are a lot harder to desolder. In general, I keep all my THT components on the same side of the board as it makes the design stage easier, and that goes doubly so for a design based off a breadboard prototype.
That protoboard has the same breadboard limitations of "only 4 connections per pin", which I often run into when I want a ground rail seperate from the +/- voltage rails. That pattern can definitely be tidier than dotboard, but also definitely less compact. I think strip-board is a better compromise, though the design phase gets tougher.

[Anonymous No.2437938]

>>2437936
>>2437936
>>2437936
NEW THREAD

[Anonymous No.2437996]

>>2437913
>Which ones, the Chinese ones or the not Chinese ones?
There are chinese ones? I guess they arr cheaper? How do i find them

[Anonymous No.2438581]

Is there a cree alternative to pic related?

[Anonymous No.2438810]

>>2431252
source --> hpf -> clipper --> recombine
.............-> lpf ----------------^