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/diy/ - Do It Yourself


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Previous chapter: >>1669514

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

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

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

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

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

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

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

>Li+/LiPo batteries
Read this exemplary resource first: https://www.robotshop.com/media/files/pdf/hyperion-g5-50c-3s-1100mah-lipo-battery-User-Guide.pdf
>I have junk, what do?
Take it to the recycler.
>>
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>>1675224
>Li+/LiPo batteries
yes
>>
this thread's digits brought to you by my dick
>>
What decent EU store has the lowest shipping?
>>
looking for 4-pin TRRS cables to connect headphones (with mic) to an Android.
every cable I find on TME is Apple only (Left, Right, Ground, Mic). what
>>
>>1675239
My two local cash & carry outlets.
>>
>>1675239
depends mostly on the specific order. Mouser can be decent if you are ordering above 50€. Ebay/Aliexpress aren't decent, but the shipping is great generally speaking.
Thing is, mostly you will have to live with bad shipping prices, so it made sense at times for me to buy at local stores in the city. They have frankly horrendous prices, but the mere fact that I don't pay shipping there made it worth it.
>>
Do I understand it correctly that this display:
https://www.mouser.com/datasheet/2/244/LCD-S401M16KR-81359.pdf
needs AC to run instead of DC? If I want to run it on battery power basically I need to add an IC to do so?

Also another question regarding LCD displays, as a general rule a reflective display is gonna draw less power than the same but transflective, as the transflective has a backlight, do I understand this correctly?

Thanks anons.
>>
>>1675321
I think it's an error.
>>
>>1675322
I mean to be fair, the documentation for this one is dogshit so I wouldn't be surprised desu. Maybe next 50€+ order from mouser I'll just get some and test it, they are cheap after all. Thanks for the info though
>>
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Sorry to keep asking regarding this one, but in the documentation is pic related (same link as before https://www.mouser.com/datasheet/2/244/LCD-S401M16KR-81359.pdf) and I haven't worked with LCD segment displays before, so if I want to turn on the number 1 on digit 1 I'd need to turn on
1B & 1C, so I'd check the table and
1B => pin 6 and com2 => pin 3 & pin 6 to high
1C => pin6 and com1 => pin 6 & pin 2 to high.
Am I reading this correctly?
>>
>>1675336
you got the pins right but i don't know if you know what you mean by 'high' and i can't be bothered looking back to find your last post to find out. you know you can't just connect lcd to 3vdc right?
>>
>>1675342
>you got the pins right
Good to know, thanks.
>you know you can't just connect lcd to 3vdc right
No, I didn't actually. I assumed the pins were logic pins (as in high =3V, low=0V, no idea what happens in high impendance state), but there's no 3V power pin so I guess I was wrong. Mind enlightening me?
>>
>>1675336

you're in over your head. that thing has 4 diff common pins, and they all require pulses at different voltage levels, and in the proper sequence. the segments also need pulses, not DC levels. fortunately, there are LCD driver chips that do all the complicated multiplexing and voltage creation. you just gotta find one such chip (usu. SMD with tons and tons of pins) that can talk to your LCD.
time to read datasheets. endless fun!
>>
>>1675350
Thanks for the warning, I'll do a deep dive and inform myself.
>>
>>1675353

the eevblog dude has a tut on LCDs. dunno if he covers units with more than 1 common.
https://www.youtube.com/watch?v=ZP0KxZl5N2o
>>
>>1675360
You saved me from a lot of headache, thanks again. Will check it out!
>>
I want to activate a switch by pulling out a metal pin. I've looked around but haven't found anything good. What kind of switch could I use to achieve this?
>>
>>1675371
Can you elaborate a bit? as the sticky states, a picture is worth a 100 words and I'm not entirely sure I understand the situation.

My first guess is a pushbutton integrated into whatever structure holds your metal pin. You slide the pin in, the button is pressed. You pull it out, the push button is no longer pressed. You can go far more sophisticated with capacitive sensors, but this is the cheapest method I can spontaniously think of.
>>
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I'm a stupid dumb 2nd year apprentice electrician scum. Recently got into electronic music and found out I have a budding talent for mixing music (I know I'll get some shit for saying that). Bought a shitty little midi controller for $100 and I've been practicing with it and pushing it to its limits

at the same time I've also recently been interested in arduino/small scale hobby electronics, especially being able to buy components for pennies on the dollar (or even salvaging them from shit people throw away) and making new things from them. I have a chinese knockoff arduino "starter kit" coming in the mail tomorrow and I'm wondering where should I start with if I wanted to eventually build my own "dj controller"? I already have a very basic entry level understanding of ohm's law and calculating voltage/current in a circuit, and an extremely baby-level understanding of drawing circuit schematics/diagrams and reading them. No experience whatsoever with programming, though.

>tl;dr: where do I start if I wanted to eventually build a MIDI controller device using arduino, or does this question belong on the arduino thread
>>
>>1675389

>I know I'll get some shit for saying that
consider this the shit. Now let's move on.

>does this question belong on the arduino thread
yes, but you're already here so I'll try and help here.

The basics are as follows:
You need an arduino and a decent amount of I/O, so an arduino uno clone should be decent at first. You also need ways to interact with it, so here's parts you should consider:

LEDs for backlight

buttons, get some that are somewhat tactile, the cheapest pushbuttons would work as well but that's not what you want.

consider switches , depending on your needs

potentiometers. You want to have both normal potentiometers and sliding potentiometers, because sliders are fun. They are harder to source though.

Get cheap plastic caps from aliexpess for your potentiometers.

Plan for an enclosure. A wooden cigar box/ custom wooden box will work fine, 3d printing one is also an option.

Learn to connect them to your arduino one by one, take baby steps. (1/?)
>>
>>1675371

i once used a 2.5mm jack. you can use either the built-in switch, or use the Tip-Ring, which will be shorted by the metal pin, depending on whether you want IN=ON or OUT=ON.
>>
>>1675389
(2/2) first the buttons, then the potentiometers, then the leds.
To do this you can just write basic programs on arduino or modify example sketches which is a decent way of learning.
Remember that your LEDs may need resistors to not burn out etc.

If you want more pins than the arduino uno clone you have has, consider other arduino based clones, also look into charlieplexing and how to read a button matrix.

Now to make this thing actually usefull: Make the arduino work as a midi controller. The software programming for that is too hard for you, but that's no problem, other people solved this issue for you before.

Google for Arduino MIDI libraries on github. There's several projects, pick your poison. Most explain how to install them and get them to work in the readme. This code will do all the work for you.

Connect your arduino via USB to your computer, and voila you got a midi controller.

If you liked working with arduino you can start doing other more complex things
>>
>>1675400
What kind of projects can I do/things can I read to learn arduino programming if I wanted to modify the functions of the buttons/knobs so I can add on or achieve different effects besides the basic ones that come with a standard MIDI dj controller?
>>
>>1675389
(3/2) Just to add one more thing: Most github pages assume you know some basic coding, so here's a roadmap what you should teach yourself to learn coding for arduino:

Install the Arduino IDE
Learn what the setup() and loop() functions do.
Learn what a variable is and how to initiate one.
Learn how to write stuff to the console (hello world at first, then once you connected your first button make it so it writes something whenever you press the button).
Learn what an if statement is
Learn what switch case does

From there the documentation in the github page should be enough to get you started.

Good luck.
>>
>>1675403
Start small, go from there. First learn the basics of programming as I outlined in >>1675403.
Except for loops these are the building blocks of every program there is for the arduino.
As for projects, it really depends on you. The arduino IDE has some example codes that do stuff like make a LED blink in intervals etc. Some people learn this way. Some get some books and read those, others watch youtube videos. You have to know what works for you.

The biggest part is working in increments. Project 1 may be if you press a button it writes "pressed" to the console.
Then Project 2 is it writes the state of a potentiometer to the console (so as you turn it it writes a number)
Project 3 iis it writes the state only while you press the button and so on. Once you know how to "read" your IO it's just a matter of understanding the midi github library and asking yourself what you want.
>>
>>1675403
If you want to learn, do these things by yourself , it'll be more rewarding.
If you want the end product, there's videotutorials out there.
Here's one by greatScott , one of the featured youtube creators in the sticky:
https://www.youtube.com/watch?v=wyKStRyez5Y
>>
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Does this seem like a decent basic soldering station for $70?
https://www.digikey.com/product-detail/en/aven-tools/17405/243-1229-ND/5658764

Intended use: soldering some audio cables, LED arrays, and USB accessories.
I've got 1224 different kinds of solder to choose between, but I guess I'll just go with something with high Sb and zero Pb.
>>
>>1675418
>110 ~ 130V
>320°F ~ 1020°F (160°C ~ 550°C)
>LCD Display, Temperature Control
>>
So I don't have a signal generator, but I need to test some audio level shit I'm building. Is there a easy way to generate white noise so I can see if the magnitute response is what I hope it is?
>>
>>1675423
>Is there a easy way to generate white noise so I can see if the magnitute response is what I hope it is?

Cut up a 3.5mm audio jack. Plug it into your computer.

Boom.

Arbitrary signal generator (with some caveats). Have Audacity generate some white noise, game's easy.
>>
>>1675336
>>1675345
>>1675353
>>1675365


Go look up the Max7219. 99% chance it'll work with your display.
>>
>>1675426
Will do, thanks.
>>
>>1675427
>>1675426

O shit, anon, ignore me. I really need to sort my reference sheets. Hold on, I got something for the LCD in here somewhere.
>>
>>1675427

actually

this anon >>1675426
>>1675429

unintentionally brings up a good point. why are you doing LCD? any particular reason?
>>
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Hey, I made an amplifier with current mirrors somehow. How does this work? And can I apply negative feedback to it in some way to reduce distortion?
>>
>>1675430
On mobile now, but basically I wanted a watch display that is low power and has a thin profile, preferably addressable with few pins. The watch is 5-6mm thick but I'm not sure how much of that I can actually use (and since I'm on mobile I can't check rn).

I thought my options were basically: binary display with leds - but I don't want a binary display.
OR a 7 segment display, where I have the choice between LED and LCD, but the LED segmented displays I have seen were too thick (however since I want to use a custom pcb I could just arrange some Leds in a 7 segment arrangement).

From here I thought using a LCD would have better power draw, as LEDs can draw quite a lot.
Some anon talked about e-ink but those are too expensive for me and also kinda overkill.

So far either using a ready chipset or doing it like the eevblog video explained and sticking with lxd seems the best option for me. I might consider both using a IC and building my own from xor gates to learn some stuff.

Did I miss something?
>>
>>1675427

Alright, sorry. Entry I have for 7-Segment LCD displays is saying PCA8561AHN. Looks like it has the right cycle and bias settings for that LUMEX, too.
>>
>>1675436
Don't worry about it, I appreciate you helping. I will check it out tomorrow, thanks again.
>>
>>1675435

No, that's not bad logic for it. It's just a shame as easy chips for LCD's are sorta going out of style. ICL7211A would've gotten you there in a DIP package but you're probably gonna have to go the route of >>1675436
>>
>>1675403
>modify the functions
MIDI devices and their CCs just output a pretty raw value of the controller, the receiving device maps them to whatever synthesis/mixing parameters you like

>>1675435
there are micros with on-board LCD controllers and bias generators built-in. I haven't seen many LCD controllers in the AVR line, but PIC and maybe various Cortex-M0-tier micros could have them. but they're easy to use, once configured they maintain like 8 bytes of video RAM or whatever in peripheral registers that you can turn on and off
>>
>>1675389
>I have a budding talent for mixing music (I know I'll get some shit for saying that
post your mixtape faggot
>>
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>>1675224
>>1675450
this thread's digits were sponsored in part before you were knee high to a blow job
>>
>>1675433

Feels like a homework question desu.
>>
>>1675535
I can assure you it's not but I can see how you'd think that. Also I think I know how to implement negative feedback. This topology ends up being not all that different from an OTA like the LM13700. The only thing that adds are an additional two current sources (implemented as two-transistor current sources rather than current mirrors) and a differential amplifier. The idea is similar though.
>>
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>pic related
what the fuck, it's huge
>>
>>1675577
And expensive. I'm guessing $20k or more.
>>
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>>1675577

>Just use a heatgun, bro
>>
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>>1675562

From an execution standpoint, harmonics in mirrors can be eliminated by going with matched pair packages to avoid the gain mismatch between discrete parts. What model are you using for the transistors in your sim?

From a design perspective, you're essentially building a truncated version of a diff. amp. loaded by current mirrors - pic related. not quite what you are getting at in your pic, but close. any reason for your approach of execution?
>>
>>1675448
Yeah, I'm most likely going to got with a IC to drive the LCD and then build my own circuit to drive the LCD as well, just as a learning experience. I certainly know too little about the topic
>>
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>>1675623
As long as 'making' means playing simgame you need no matched pairs, every 3904 is exactly the same because there is only one spice model, or is it?
>>1675562
Good luck.
>>
>>1675619
Do you say that sarcastically because using a heat gun would also reflow the SMD components on the bottom?
>>
If I want the highest possible SPL at certain frequencies, is this achieved by internally driven piezo buzzers?
>>
>>1675692
>SPL
What does that stand for? What's the context?
>>
>>1675692
No, you can always produce more.
>>
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God fucking damn it I hate trying to program chink shit
This is confusing as hell
>>
>>1675692
You say certain frequencies without specifying what frequency, we cant help you unless you say what frequency range, good job and report to reddit
>>
>>1675700
>What does that stand for?
If you don't know what that is, then you don't need to bother replying.

>What's the context?
The universe. It's a general question.

>>1675701
Sure. But at, say, 3 KHz: Is an internally driven piezo buzzer going to be the most effective at converting rushing electrons to sound waves?
>>
>>1675713
>If you don't know what that is, then you don't need to bother replying.
I'm just a curious guy. The time it took you to write that sentence is more than it would take to write out what the acronym stood for.
>>
>>1675713
>>1675719
Oh it's sound pressure level. Anything along the lines of a driven harmonic oscillator would likely be better if you're optimising for a single frequency, and piezos fit the bill pretty well, at least if driven with some sort of self-resonant circuit. But there are different metrics by which to use, such as pressure vs driver area, pressure vs driver volume, pressure vs driver mass, and pressure vs electrical power. Pressure itself likely isn't the best unit in the first place, I'd say that a flat out kinetic power or force output would be more applicable to a situation where the area of the driver isn't a particular constraint. The distance at which you want this SPL at (and hence how focused the sound itself is) is also something to consider, perhaps using something like a phased array of smaller piezos could prove more useful than a single larger piezo in some circumstances.
>>
>>1675713
May well be effective enough for your needs.
>>1675719
Sound Pressure Level
banned by google?
>>
>>1675730
I know waffling when I see it.
>>
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I want to generate a voltage that relates to the bottom peak voltage of a sawtooth.
I came up with pic related but I'm not good with electronics yet. Is there anything obviously wrong about this? Are there any improvements I should consider?
>>
>>1675745
Where does the initial charge of C1 come from?
>>
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>>1675773
gets brought up in the first 140ms.
>>
>>1675814
No, it starts at about +11.4V, not at -0.5V.
>>
>>1675827
yea, I think thats because my initial conditions were bad.
>>
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>>1675745
maybe like this?
>>
>>1675680
>every 3904 is exactly the same because there is only one spice model, or is it?


Some models have some variance parameters inherent in construction to make simulations a bit more accurate.

it's sort of a crap-shoot though, so you're not wrong, most default models are pretty simple. I think anything that's straight Ebers-Moll default probably doesn't incorporate variance.
>>
Any help in rebuilding this concept (not with a Fawkes mask, that's not the point). What is this glowing wire? Malleable neon sticks? I don't see any single LEDs.
>Also
I'm guessing that these neon things are all individually connected to a battery (one for the beard, one for the eye..). What's the best way to have all the wires use the same battery?
>>
>>1676025
Look into "EL wire" or "Electroluminescent wire". That's most likely what they used.

>I'm guessing that these neon things are all individually connected to a battery (one for the beard, one for the eye..).

Almost certainly not, that would be retarded, why would you have 6 different batteries for one mask.

>What's the best way to have all the wires use the same battery?
There's multiple:
- either use just one wire and run it through the mask as well (so there's connecting parts on the back),

- connect it in series (remember voltage is added in series and amperage is the same)

or connect them in parallel (voltage is equal but amperage is added to a total).

It's really not hard to build, just figure a place to put your batteries, put a switch inbetween and buy some EL wire from ebay or aliexpress.
>>
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So there exists this thing: https://pavlok.com/

I know it's retarded, but the idea is interesting to me. Thing is I'm not going to pay 150-200$ for what can be archieved with a rubber band on your wrist, so I want to build a similar circuit. Online there seems to be pic related as a suggestion. Thing is would this even work with DC?
Is the "pulse" from the pushbutton enough that the transformer works?

Why did they connect the transformer sides with each other?

And is there any way to get a transformer like that that's really small? Best guess I have is a audio transformer, but even those are somewhat thick.

Or is there a better way to build a small shock circuit that doesn't kill me AND doesn't cost 200$
>>
>>1676025
el wire needs a dc-ac converter, about 100V, different frequencies. converters are not expensive.
>>
>>1676067
When you buy it on ebay you get it with a box that does it all for you, and that box is small enough to attach somewhere for a mask etc, so just do that desu
>>
>>1676056
>there exists this thing
A zapper doesn't shock, it zaps, perodically. If you need a healthy shock, get a cheap electric fence kit.
>>
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Does anyone have one of these in an american style of a plug? What are they called and where do you get them? Alternatively, what's inside of them (I'm guessing just a single wire with no resistor etc)?
Anyone made one of their own?
>>
>>1675731
>banned by google?
No I was on this wikipedia page and assumed it was something digital enough to be in the top section, so never bothered scrolling down to see the "Science" section.

>>1675743
You're probably right, but at least half of those are valid considerations for an overly vague question.
>>
>>1676056
Look into flash globe transformers, they've got a high turns ratio in a small package.

>>1676161
What does it do?
>>
>>1675706
Thats what you get for cheaping out and getting chink shit
So many people raging over bad parts or components not working right, when you all try to save a few pennies by buying 3rd rate garbage.
>>
>>1676172
>What does it do?
you plug it into the power socket and then you plug your ESD strap into it.
>>
>>1676161
>>1676184
Most anti-static wrist straps actually have a 1M resistor to ground rather than a direct short. I don't know whether that's the same as inside that box but that is a standard.
>>
>>1676189
I think the 1M is in the strap itself.
I have no idea if the plug also has one. That's why I asked. I'm hoping someone has one and can open it up or just measure resistance with a DMM.
>>
>>1675745
what you want is a peak detector, turned upside down. you should look that up in an opamp cookbook

>>1676056
that's about where the design starts, yep
>Thing is would this even work with DC?
ac is not always periodic. the change in current causes the change in flux that couples
the next step up is to borrow from boost converters and operate the switch automatically, at frequencies from 10-20000Hz, with various burst lengths and frequencies. things start to get sPiCy
>transformer
wind one? toroid cores and magnet wire can be gotten cheaply. they're an adventure to wind tho. also, you might be able to build a second winding on a random small power inductor. also check into xenon flash trigger transformers, I think Mouser might still source them
rule of thumb for experimentation: don't let current flow across your heart. use an insulated push button to fire any tests. when working on the circuit and >50V is available for inadvertent contact, keep one hand in your pocket

>>1676181
chink PLC is fine, namefag is not
>>1675706
/ohm/ RULE 4
>>
What diameter tooling do they use for the edge cuts on PCBs? I'm wondering if it would be better to do a large-diameter mounting hole as a drill or as an internal edge-cut.
>>
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To the guy in the last thread who said I wired up the wrong leads to the pot...you were right. in my defence i couldnt see where pin 1 started and my only choices were pin 1 -2 and pins 14-15. if you flip the connector around you can get them mixed up.
Anyways its wired to the pot now and working fine although the volume isnt a smooth increase but i guess thats what happens with a log pot.
>>
>>1676248
>you were right
I know.
You're a good boy anyway.
>>
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>>1676256
thanks. you can come and play the organ any time
>>
>>1676211
1-2mm or so ig
expect that most houses just won't do plated through slots because it requires breaking process flow for an extra milling step, but 5-6mm should be a safe maximum diameter for a plated through hole. non-plated slots can be done as part of the routing step, but board houses may incur an adder for the extra time taken
>internal edge-cut
aka cutout
in all cases consult your intended board house for their own specific process limitations. they'll tell you if special accommodations are recommended or required for internal cutouts, usually on their website under capabilities
>>
>>1676272
Doesn't need to be plated, just mounting holes for screws
>>
>>1676335
I'd figure they're using the same drill sizes from one end of the shop to the other, so drill up to 5mm, use a cutout for larger
>>
>>1676181
Uhh that VFD was 5hp and 160 dollars, the cheapest name brand ones are like 3 times the cost and up
>>1676204
It's not a PLC
Sperg more loser
>>
>>1676139
>cheap electric fence kit
tempting, but I want a small form factor. Thanks anyways.

>>1676172
>flash globe transformers
Thanks, will do.

>>1676204
>xenon flash trigger transformers
Thanks, I'll look into it.
>don't let current flow across your heart. use an insulated push button to fire any tests. when working on the circuit and >50V is available for inadvertent contact, keep one hand in your pocket
Thanks for the warnings, I'll do my best not an hero because I wanted to replicate what was a bad idea in the first place.
>>
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>>1676374
If you come across a disposable camera you have all the parts you need. You could even use it as it is. Don't touch C2 to avoid the big shock. T2 can produce a funny spark if disconnected from FL1.
>>
I'm looking to keep tabs on health-relevant things in my apartment, such as:
>Temperature, pressure, moisture, air draft
>Illuminance (sun, lamps) and UVA/UVB (sun)
>CO2, CO, NO2, NO, SO2, H2S, O3, O2
>Radon, ionizing (background) radiation
>Airborne particulates (PM2.5, PM10, et c)
>Noise levels (road, et c)
>Volatile organic compounds (VOCs, such as formaldehyde, benzene, BaP, PAHs)
>Microbial contaminants (mainly mycotoxins)

Sensors to Arduino/rPi via I2C, then I'll graph in Qt.
As for radon, most of the designated radon sensors seem quite pricey. Apparently "radiation detectors that don’t have an alpha capability are much less expensive" and "low-end Geiger counters do not detect alpha".

I'm considering using an unshielded CMOS like in this article:
https://spectrum.ieee.org/geek-life/hands-on/how-to-build-a-homebrew-radon-detector
I've also looked at these other techniques:
https://web.archive.org/web/20071224165447/http://www.radongas.org/device.htm
Any other tips on making a reliable and accurate alpha detector?
>>
>>1676399
Read more about the CMOS detectors, and it seems the pixels are ruined by alpha exposure.
>>
>>1676351
>that VFD was 5hp and 160 dollars
That should fucking tell you something.
>>
>>1676399
where do you live? Venus?
>>
>>1676435
Almost. Scandinavia.
>>
tore open a dead computer psu and am wondering what a component is

yellow plastic cuboid, 2*2*1cm
the 2 pins are across 220v ac, very close to where the wall outlet wires come in
its marked as cx2 which makes me think its a capacitor because the ceramics are cy_ and electrolytics c__
it also makes me wonder where cx1 is, cant find it
>>
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>>1676501
sounds like a mains input filter capacitor. post a pic if you want to be sure. if you can't find cx1 it may not be populated (based on emi testing) or it may be soldered right up at the mains terminals.
>>
>>1676439
Nice, I'm going to sweden as a EE exchange student next year. Is it true that the swedish government forces you to marry a busty, rich, faith and lustful blonde once you get there?
>>1676501
Capacitor probably. Those pc supplies get more packed and crowded by the day, so you probably just missed Cx1
>>
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>>1676425
Yeah man let's spend 800 dollars on a VFD forq belt grinder that has 500 dollars total investment in it, great fucking idea lol
I bought this unit because it has the most support online, it's still a confusing mess to use but I got it programmed.
>>
fuck off namefag
>>
im gay btw if that matters
>>
>>1676272
>most houses just won't do plated through slots
??
JLC did it for me without any question.
>>
>>1676399
>Sensors to Arduino/rPi via I2C
you may also want to consider a 1-Wire bus if you want to spread your sensors over a wide area with a minimum of wiring.
>>
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>>1676670
>>
>>1676399
While end-window detectors are pretty standard for alpha, an open-air ion chamber might suit your purpose better.
>>
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>>1676693
>>
>>1676670
I2C can do multiple sensors in parallel anyhow though, right? Not like he's using an 8-pin micro or anything.
>>
>>1676702
"""1"""-Wire is rated to supply power to slave devices over tens of meters, some host interfaces even provide a timed strong pull-up to help
otoh I2C and other "logic level" buses are only good within about 1m
>>
>>1676703
yes but less sensors support it, I can't see him requiring a full 10+m of distance if he only has one of each sensor; he can have them all next to the main micro
>>
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>>1676701
Good idea, works with special one-wire light bulbs.
>>
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>>1676713
this anon gets it
>>
>>1676399
>health-relevant things
No mental health sensor? The first that goes is the ability to detect the condition.
>>
>>1676726
but that's all just smrtphone software
>>
>>1676728
certainly, join the new class action suit
>>
>>1676755

so THAT'S where the voices come from
>>
>>1676775
yes, via a free REST API offered by google in partnership with the CIA
>>
>>1676579
>>1676595
Post more for me lol
>>
>>1676805

so THAT'S why the voices keep telling me to allow javascript
>>
resistor help?
black blue gold silver green
meter says 0 ohm so its probably something low

what does the green mean
>>
>>1676890
measure inductance
look for 5 band color code
include mil codes
>>
>>1676890
Are you sure it's a resistor? It might be an inductor.
>>
>>1676703
>I2C and other "logic level" buses are only good within about 1m
I'm a proponent of 1wire, I use it for my own temperature sensors, but you can extend I2C over tens of meters if you slow the clock down and use stronger pullups. I'm running I2C over UTP cable with a 10KHz clock. Good results so far, we'll see how well it holds up as I add more nodes.
>>
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>>1676920
>tens of meters .. more nodes
Good experiment. How do you wire the UTP pairs, any termination?
>>
>>1676944
I have sda/scl as one pair. I was going to split them across two different pairs to minimize capacitance between them, but haven't needed to. Maybe later.
No termination, just a pair of 1K pullups at the master node.
The idea is to run wires and make splices wherever is convenient, making for a very chaotic bus topology. I think most problems with that can be solved by slowing the clock, which I can do because it's only ever sending a few bytes.
I2C isn't meant for this sure, but I needed a multi-talker multi-listener bus that could support weird topologies and didn't need high bandwidth, so I think it's fitting the bill.
>>
>>1676964
Sounds good. Capacitance of a twisted pair is about 50pF per meter. Power over UTP (5V or so) should also be possible. Termination is difficult because UTP is about 100Ω, just right for USB..
>>
I tried making picrel circuit for phase-fired control of inductive motors, but it doesn't work. I checked it out with the fan motor (120W) for which it is intended and with an ordinary incandescent light bulb, but it just delivers 100% of power all the time, no matter what the potentiometer is set to, as if the triac was always on.
I don't have access to any other tools other than a multimeter.
>>
>>1676978
I already have power over the UTP, 24v for relays. I was going to drop that down to 12 volts to directly power the Pro Micro boards I'm using for bus nodes, but although their regulator is rated for 12 volts it begins to fail at 11 and blows if you exceed 12v even slightly. So I'm going to have a buck converter on each node and might as well stick with 24v. With the buck reg they'll hardly sip current at 24v so going a long distance over 24ga wires will be no issue.
50pf is nothing at 10kHz, so that's encouraging.
>>
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>>1677086
I had a similar experience with an old Canon A640 over CAT5/24, two pairs for USB and two for 12V, regulated to 5V at the camera because without that the start-up current triggered the low-bat alert which didn't go away. DC/DC converter was 6.5-42V to 5V/1A, about the size of a sugar cube. Worked up to about 10m, then the USB got stuck.
>>
>>1677084
I know that single phase induction motors do not like dirty electricity, but the light bulb should work. I would disable all the fancy stuff west of R7 (disconnect D1 and D4) and see if the bulb does what it should. If not then disconnect R3, bulb should stay off. If still 100% then T2 is dead.
>>
Anyone know about those 9-fet ebike motor controllers? I understand how you need 6 fets to produce alternating currents on 3 phases, and how adding more fets in parallel increases their current capacity. So the number of fets would be 6,12,18,24, etc. So the question is, what exactly is up with 9-fet controllers? Anyone have a schematic of the circuit or knowledge about them?

I think the extra 3 fets might be added to the "bottom" of the bridge circuit to make transitions easier but not 100% sure.
>>
>>1677144
Thanks. I did that. I disconnected the things on the left, then R3 and even R5-C2 to be sure, and it's still the same (bulb lights as if it was connected directly to the mains). So the only way for the current has to be through T2. I also checked the resistance on the anodes of T2, but there seems to be no short.
>>
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>>1677175
Triacs have two main terminals and a gate. The MT2 pin is usually connected to the tab. You could disconnect R4 to be sure that nothing can trigger it. And of course look for possible wiring flaws..
>>
>>1675582

>$20K

Oh ho ho. you're cute.

pic related. it's the VU13P price.
>>
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>>1677275
>>1675582

forgot pic
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>>1677276
hooly shit.
makes me wonder what's the most expensive single item you can buy on digikey.
>>
>>1677276
granted plenty of companies and the military don't care about a $90k pricetag, but why not mesh a couple $500 fpgas if you need that many cells?
>>
>>1677289
what is "a couple" in your mind? a couple usually means two, or a few.

you'll need like 50 to 100 $500 fpgas to get the same amount of logic blocks. and it won't be near as fast and won't have as many features.
>>
>>1677276
>448 I/O
>2577 pins
wtf does each pin get its own Vddio and Vref

>>1677289
it's not just cells, it's fabric. a board-level interconnect between the two chips costs more in power and speed
>>
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>>1677295
wew
>>
What butane soldering iron should I get?
>>
>>1677311
None, ts100 is better
I power mine off a lithium drill battery
>>
>>1677313
But that is not butane, it is electric, and I don't have spare batteries to power it.
>>
>>1677315
Get an extra battery?
Get a ts80 that runs off USB?
Build a battery pack?
Be resourceful, this is diy after all.
Butane soldering irons suck ass, they clog up, valves start leaking, poor heat control, takes forever to heat up, butane runs out fast and you have to carry a can with you.
They suck.
>>
>>1677317
>Butane soldering irons suck ass, they clog up, valves start leaking, poor heat control, takes forever to heat up, butane runs out fast and you have to carry a can with you.
>They suck.
Do they really suck that much? I thought they had good temperature control though, since you can adjust gas in wide range, from 10 to 60 W, which is a lot for tiny thingy.

I tried using mains soldering iron for car wiring, and cable gets annoying really quick.
>>
>>1677317
>>1677320
The only time a butane iron is worthwhile is if you're making repairs in awkward remote spots where you can't get power. Then it's worth it because the whole iron is self-contained and fits in one hand.
They have practically no temperature control, almost always run too hot, and you also have to worry about the hot blast coming out from around the tip. They're about only good for making wire splices (not that I haven't soldered a PCB with one).
I have a hard time believing you have no kind of battery that can power a TS100, those things will run on just about anything.
>>
>>1677321
So they are super shit, right?
I mean, I tried soldering SMD with butane torch, had no problem with controlling temperature, though at low setting flame always wanted to put itself down.
>>
>>1677334
did you have success with that? with which torch?
They have their niche, outside of it they are very much inferior to electric. there's a big difference between rough power control and feedback temperature control.
I usually carried one of these generic radio shack irons for work. it did well enough for what it was.
>>
>>1677346
>did you have success with that? with which torch?
Yes, more success that with hot air gun (non-electronic, but for heating stuff, 1600 W monster, which will blow SMD resistors off the board and overheat FR4 ).
> there's a big difference between rough power control and feedback temperature control.
Yes and no. This is why old non-controlled irons were pretty big. They were wasting energy on heat.
New irons are PTC, so they are self-controlling. Also thermal feedback.
>>
>>1677348
>1600W monster
the correct torch for an apples-to-apples comparison is Elon Musk's flamethrower, which I'm sure you have enough sense not to use to reflow a board unless trolling
>>
>>1677353
Torch I used says 1.75 kW on package. But I can tune it to give a tiny flame. 100-300W maybe.
Hot air gun has like 3 settings, high air low heat, low air high heat, and high air high heat.
Low heat is 150C and high heat is 450C.

Also, flux will burn, since it is alcohol, so yeah, not perfect at all
>>
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>>1675224
What would /ohm/ suggest for a first multimeter?
A Fluke would be a nice investment, but I would rather get a cheap-but-quality meter to familiarize myself with electronics first, then buy a 87V later on when I am knowledgeable enough. The 117 doesn't have mA.

I'm leaning towards the EEVblog Brymen BM235 Multimeter. It seems adequate enough for a beginner like me. Are there any alternatives?


(This is probably not the right thread to ask, but I just wanted to know this general's opinion. I already posted this in sqt anyway.)
>>
>>1677389
What will you use it for?
All of those are waaaaay overkill for someone who's unfamiliar with the basics.
>>
>fixing earphones
>right ear is desoldered, left ear working fine
>resolder right ear
>left ear stops working, right ear now working fine
ok what in the fuck happened

>>1677389
Aneng AN8009 is a cost-effective and highly decent iron
>>
>>1677389
I started with a used fluke. It was pricey enough but very pleasant to use compared to cheap chinese meters at the time I bought it. Nicest parts were autoranging and fast display update.
>>
damn, son
https://github.com/openscopeproject/InteractiveHtmlBom
>>
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>>1677403
Bro I wouldnt tell someone to cheap out on a meter, for many reasons.
Safety is one and having a nice meter is something you'll never regret, I'm no expert but I still have 3 fluke meters, you should never be limited by your tools and you should try to avoid having your tools limit you.
A small investment gives you a lifetime tool you can trust and is safe.
I bought all mine used btw, one 87 was 100 other was 150 nearly brand new.
>>
Ehi guys, I was wondering, which is a good soldering iron to start with?
>>
>>1675713
>If you don't know what that is, then you don't need to bother replying.

You could have just replied spl = sound pressure level, but you just had to reveal having a small dick and act like a primadonna.
>>
The Brymen BM235 Multimeter looks just fine. If you're willing to spend the $125.00, it should serve you well for many years. If you do buy it, don't leave it unused for long periods (three months or more) without removing the batteries since alkaline cells tend to leak once they are fully discharged.
>>
>>1677615
AGAIN with thinking about other men's penises
rule #0 of /diy/ is google it, faggot
>>
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>>1677621
>spend the $125.00

https://brymen.eu/shop/
Brymen BM235 - 3 year warranty
85.80 € incl. VAT (23%)
Silicone test leads BL21S2-T4SC
9.60 € incl. VAT (23%)
Fuse 11A/1000V 10x38 mm
9.50 € incl. VAT (23%)
Fuse 0.4A/1000V 6x32 mm
9.50 € incl. VAT (23%)
Shipping
GLS Express 9.90 €
----------------------------
delivered:
124.30 € incl. VAT (23%)
>>
>>1677681
Whatever, dicklet loser.
>>
>>1677720
put your name back on
>>
As someone who has very limited experience with datasheets, I'm trying to wrap my head around

https://www.mouser.com/datasheet/2/268/21945e-81547.pdf

If you look at the pin layout for the chip family most are self explainatory, but two are not:
CS (on both chips) and NC on the MCP4021. I thought CS may be some sort of clock signal? No idea about NC though.

Is anyone with more experience kind enough to clarify/help me?
>>
>>1677740

CS is chip select. in this case it's got a bar over it meaning the chip is selected when you bring that pin low. NC is no connection.
>>
>>1677740
CS in this case is a chip select.
Pulse the up/down line only works when you drive ~CS low, the direction seems to change based on the UD input when you first drive CS? I think I just skimmed it
NC is not connected. Just dont connect it.
>>
Starting with programming stm32 MCUs and wanted to hear opinions on setting up environment. Specifically Libopencm3 or CMSIS, chibiOS or freeRTOS and a good book that covers those cases.
>>
>>1677759
>>1677763
>CS is chip select so simple, yet I didn't get it. Makes sense though.

>NC is no connection.
Thanks for clarifying, that feels pretty unintuitive to new people though.

Anyways, thanks anons, that explains how I'd use it.
>>
>>1677769
As you know about CMSIS, you are probably not that new to embedded. Try the (relatively new) STM32CubeIDE, it is basically a stm eclipse without the need to install a gorillion of addons (GNU MCU, etc...). You don't have to use "it" (HAL lib, low level lib), but you can crwl through an empty project you created and see how the stm32 mcu's use CMSIS. Oh, and there is an FreeRTOS config assistant too. And STM32CubeMX is integrated too.
>>
>>1677769
>>1677783
And I'm curious too about book suggestions.
>>
>>1677706
>STC
dropped

>>1677784
y tho, when both the vendor and the community offer sample code out the ying-yang?
>>
>>1677609
chink T12 OLED station
>>
>>1677865
T12-K chinkstation #1
>>
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Rate my Pro Micro breakout board. Includes the tiniest buck converter I could find, for power supply flexibility.
>>
>>1677889
Acceptable.
>>
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>>1677889
is that home-fabbed? can't rate until I know
also, that's a pretty big buck, there are smaller modules available, or you could have put the buck on the adapter board directly, a bare minimum converter IC only needs 5-6 external components
>>
>>1677900
"home" fabbed. I made it after hours in the company shop on a Nomad mill (w/ kicad, flatcam, and UGS)
I didn't put the buck converter on the PCB mostly because I wanted to keep the bottom flat and didn't want to mill a 2-sided board, and wanted very quick assembly. these days personal projects have to be quick above all else.
>>
>>1677903
fair enough. 6/10
>these days personal projects have to be quick above all else.
sad but understandable
>>
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>2am
>design a buzzer circuit for a pcb
>get the mosfet footprint backwards and forget the flyback diode
>>
>>1677950
Classic
>>
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I'm asking for career advice here.
Currently, I study EE (first year), and I'm sorta broke.
How can I earn money using some /ohm/ skill I have?
First thing that comes to mind is laptop/phone repair. Problem is, I have enough brain (at least I think so) to identify problem correctly, but fixing it is difficult, because I don't have proper gear.
How can I get started in repair? What stuff should I buy of high quality, and what stuff I can buy shit quality? How do I gain experience (cheapest way)?
How much money can I expect to earn this way?
>>
>>1677970
>How do I gain experience (cheapest way)?
by recognizing underemployed anime-loving neckbeards as the infallible sources of career advice that they clearly are
or, by finding a local repair shop and working for them, because undergrad programs don't prepare you for industry, they prepare you to prepare yourself
>>
>>1677970
Phone repair is really fiddly work, and you need at least somewhat of a selection of rather specialised tools (like those microwavable heated pads). So I'd opt for picking up broken consumer electronics from junk shops for peanuts and repairing those, especially simpler or older ones that would be easier to repair.
>>
>>1677974
>Phone repair is really fiddly work
True, they are too small for my liking, and too much under-fill.
I'm looking towards laptops and similar shit, since those basically require hot air, soldering iron, and some might require some form of under heat.
SMDs aren't that tiny, and I have experience repairing couple audio jacks and power jacks.
>So I'd opt for picking up broken consumer electronics from junk shops for peanuts and repairing those, especially simpler or older ones that would be easier to repair.
Where can I find such place? This is real question.
I tried searching local ebay and craigslist, but I can't find any lots with "broken laptop, I spilled coffee please take it for $2"...
>>1677973
>by finding a local repair shop and working for them, because undergrad programs don't prepare you for industry, they prepare you to prepare yourself
Who needs a neckbeard with experience only of breaking things?
>>
>>1677975
I tried uni recycle bin (third world, hard to find recyclers, obviously. Digging landfills isn't great), but all phones and one tabled were fuckered by other people, and I can't unfuck a burnt hole in multi layer board.
Should I make "I will buy broken crap for 1-5 USD" listing?
>>
>>1677975
>I tried searching local ebay and craigslist
It's likely not worth advertising <$5 worth of broken goods when you can take it to the trash or flip it at a junk shop. I happen to live next to one, but look around. Junk metal shops might also have things that you'd be able to repair and sell as opposed to leaving them to disassemble and melt them down. Perhaps the kind of places that YT guy "post apocalyptic inventor" visits might be more up your alley.

In general I'd steer away from anything with lithium ion batteries or hard drives in them, the former don't sit around in a shop or dumpster terribly healthily, and the latter tends to be removed entirely, meaning you'd be paying for replacement parts either way. Food appliances might also be unexpectedly filthy. Simple mains appliances like older TVs, computer monitors, and heaters, along with power tools are likely to have the best bang for your buck. Bonus points for hanging around industries that throw shit away the moment it starts to act up (e.g. construction sites, whoever's at that office building that dave jones works in).

Hand tools at garage sales can also be unexpectedly good finds, but polishing them up isn't really electronics at all anymore (unless you include electrolytic removal of rust).
>>
>>1677978
>Perhaps the kind of places that YT guy "post apocalyptic inventor" visits might be more up your alley.
I have seen couple of his videos. Still have no idea where does he takes all his electronics junk.
>In general I'd steer away from anything with lithium ion batteries or hard drives in them,
I'm not interested in reselling (or do I?), but more in some practice. Because I'm kinda bad with soldering, and I have very little experience dealing with problems IRL.
This is why laptop with shot HDD and battery, and liquid damage might work for me. I still would be able to fix the liquid damage.
After fixing 5-10 boards, I think I can safely make a listing "will repair your laptop for cup of noodles" in university or something. I won't be afraid fucking up more.
>imple mains appliances like older TVs, computer monitors, and heaters, along with power tools are likely to have the best bang for your buck.
LCD monitors are pretty easy target. You can buy broken (dead caps or dead lamp) for nothing, and sell it for 10-40 bucks. Especially older ones, since they had better colors, than cheap shit they sell today.

Idk, when I see some junk on street, I take it home. Now I have fully working laser printer (which only required new 220V cable), a fridge compressor (have no idea why I took it, but it works), and 5 li-po pouches from macbook, which seem to work.
>>
>>1677975
>Who needs
the "studying EE at University of Lower Elbonia" gets you in the door. then don't break stuff

>>1677977
"donate your broken electronics HERE to help students in need"
even word of mouth might bring some donations
>>
>>1677983
>then don't break stuff
I can't. That is tempting...
No, really, I'm kinda slow when it comes to repairs, and I have doubts they will teach me, because most of repair shops are ridden by individuals, and they don't like teaching, because you work for a while, and open your own repair shop. And my schedule doesn't allow working in shop.
>"donate your broken electronics HERE to help students in need"
>even word of mouth might bring some donations
Good idea.
>>
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I'm testing this simple current to voltage converter for measuring the current through a load (the potentiometer in the diagram). V_out is measured with reference to the positive input of the op-amp. I_out is then computed by dividing V_out with the known resistor value in the feedback loop. This doesn't seem to work well when the load drops below 1K. I get a pretty large error compared to measuring the current with a multimeter. Any ideas? The op-amp is an AD824.
>>
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What is that white shit on the pins?
Did some chink rubbed on out on the board or what?
>>
>>1677993
I measured it with multimeter and thank god it is not conductive so no shorts, but should i like attempt to remove it or something?
>>
>>1677994
Scrub with 99% isopropyl and a tooth brush
>>
>>1677993
>>1677994
Flux. Why bother removing it?
>>
>>1677988
>table
8/10 alright I'll help
first thing that comes to mind: how many ohms through your ammeter?
>>
>>1677988
Isn't that circuit basically sinking current through the ammeter to the output of the op-amp? You might be running into the op-amp's output transistor V_CE (no clue how they get that down to 15mV). If it works for your circuit then sure but usually you want your current sense resistor to be significantly less than your load resistance (i.e. <1%) and your load be basically directly across VCC-GND.
Can't be bothered doing the DC transfer/gain function for that, but I assume you have?

http://www.ti.com/lit/ds/symlink/ads1113.pdf
Take a look at the current measuring circuit in this ADC's "typical application" section, looks pretty decent, with or without a r2r opamp.
>>
I bought a device from chinks and they supplied a 24V power brick with it that looks like typical notebook brick.
But the one thing i immediately noticed, is that compared to a typical notebook bricks the chink one is super light.
So i turned it on and measured the voltage which really is 24V DC... BUT... then i switched the multimeter to AC mode and measured the voltage between the + of the DC output and the earth/ground pin in my 240V AC outlet
The multimeter is showing 100V AC. (The voltage in my EU outlet is 240AC)
Am i correct in assuming that this is an unisolated power brick so if i touch the +24V DC with my hand and then something grounded, like say a water pipe in my house it will kill me?

Am i correct in assuming that this is
>>
>>1678079
No not necessarily correct. That could just be coupling and it could be high impedance. Try connecting a lightbulb from there to ground, if it lights, then you have a problem.
As a rule, chinkshit should always be taken apart and examined before use. Especially if it feels too light.
>>
>>1678081
Well i tried it with my regular notebook bricks and they all show between 0 - 7V AC tops measured against the ground pin

The chink brick is impossible to assemble without me basically hammering it open, is there some way to check with just the multimeter if it is isolated or not?
>>
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>>1678084
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>>1678085
Sounds like a challenge.
Chink PSUs aren't welded that good, so it is easy to disassemble
>>
>>1678084
>is there some way to check with just the multimeter if it is isolated or not?
Some meters have a low impedance volts setting. If you're doesn't, try the lightbulb.
To open these things up if they're welded, clamp it in a vise across two diagonal corners and squeeze until it pops. Then repeat for the other two corners.
>>
>>1678079
Ghost voltage. Terminate the meter with 1K or two.
>>
attended an event yesterday. knew some people performing, walked around backstage. some guy there couldn't play sound off his iphone. he had a minitele to xlr connection to the mixer. As soon as I got there I handed him my android as well to see if it could play any sound, and when that didn't work I took a closer look at the mixer table.
I soon saw what the issue was.

Phantom power was on.
FUCK.
>>
>>1677988
If so Vout would be negative. If you trust Vref and Rf you have the 'load' current. If you also trust the 4V you can calculate the real 'Z' (should be R because DC) which includes the A-meter. 4883Ω --> 4658Ω, 1982Ω --> 1870Ω, 508Ω --> 537.8Ω (verify). Do you trust your Ω-meter?
>>
>>1678143
(my phone's audio no longer works)
>>
>>1678159
A DI box should isolate the phantom power just by nature of the transformer inside.
You had a direct XLR to 3.5mm cable? That's odd and wouldn't have worked properly anyway. With the hot and cold lines connected to the left and right outputs.
Anyway you're right fucked. There probably is no fixing that.
>>
Does anyone here know anything about PC motherboards? I have an ASUS mobo and I'd like to order an extra BIOS chip because I plan on upgrading and changing some things and don't wanna fuck it up.

I took a pic of the BIOS chip but can't quite make out exactly what the numbers mean. Can someone pls help me source a suitable replacement? It's a WINBOND DIP-8 chip.

>WINBOND
>25Q64FVAIO ??? (not sure)
>1314 ??? (not sure)

Thanks!
>>
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>>1678311
>>
>>1678311
Have you tried digikey? Just try searching for winbond dip-8 and narrow down from there.
Pretty sure that's a serial flash chip, might work as long as you know how to correctly program it.
>>
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>>1678143
>>1678200
>wouldn't have worked properly anyway.
I took a look later today.
it appears they connected these two ...
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>>1678200
>>1678345
via this
>>
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>>1678200
>>1678346
to this. 48V per "mic".
yeah, it's gone.
>>
>>1678311
>>RULES
>0. Electrics ≠ electronics. Appliances/mains stuff to /qtddtot/ or /sqt/. PC assembly to >>>/g/.
kill your self
>>
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>>1678311
25Q = SPI flash, 64F = 64Mbit (8MB), V = ~3.3v, A = DIP package, 1314 = made 13th week 2014

Can get em off ebay cheap, they seem to be discontinued from legit western distributors now.

What are you changing?
>>
>>1678353
Thanks so much anon! Looks like a match!
I plan on flashing Coreboot on it. Do you have a recommendation for an eeprom reader/writer by any chance?

I'll flash the chip I buy and leave the original as it is.
>>
Which is more dangerous: a supply outputting 40kV with a 40mA current limit, or 240V one phase from an outlet?
>>
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>>1678200
>>1678143
Interesting. Is there a way to design a circuit to protect against 48V phantom power on the line?
I'm just an audio amateur but I do have a USB interface and a mixer thta has phantom power and quite often plug in dynamic mics that don't use it.

It'd be cool if there was a way to plug something inbetween that would stop phantom power yet also let the signal though...

Any ideas anyone?
>>
>>1678369
isolation transformer would do but the board might not like it if you short it out.
problem is are you going to leave it plugged in all the time or move around and forget to plug in the converter the same way you forget to switch it off.
>>
>>1678350
Be nice if your phone had a DC-blocking capacitor in there.
>>
>>1678369
>stop phantom power yet also let the signal though

That's called a high-pass filter
>>
>>1678374
it probably does, the amplifier will probably require one. most likely it broke down at 48 volts.
>>
>>1678384
Isn't 50V pretty standard for these capacitors? Or do the higher value (1µ) ceramics have significantly lower values?
>>
Has anyone in here tried radio astronomy?
Even simple stuff like the sun going up and down.
>>
>>1678377
>That's called a high-pass filter
wouldn't that be a low pass filter?
>>
"memristor"
holy shit i thought i knew enough about electronics but this is the first time i hear about this shit. how come.
>>
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>>1678368
40kV has the added soupçon of arc flash to help ruin your day

>>1678369
MOVs

>>1678374
>>1678384
nah, caps cost real money. device designers usually use a capless headphone amp that drives the common terminal of the jack to some voltage above ground, in order that current can be passed through each voice coil in both directions. Pic related, lower right. this is also the cause of approximately one anon per thread complaining of squeaky noises when they connect both power and audio to a system of common grounds
>>
>>1678414
this level of integration: welcome or obnoxious? discuss
>>
>>1678366
The generic cheapo china programmers should work fine https://www.aliexpress.com/item/32764455938.html
>>
>>1678420
I have to admit, it's welcome. It drives down the price of electronics for everybody, and it also makes advanced projects more accessible to hobbyists.
Combining audio, battery management, LED drivers into one chip seems ridiculous, but if I was going to design a media player, I'd choose a chip like that. And that helps put that project in reach of a hobbyist, as it never would have been earlier in the century.
Another example that comes to mind is all-in-one powerbank chips.
>>
>>1678414
>MOVs
anon, you seem to know wtf you're talking about. I have a more general question.
say I want to build a device that sits in between a mic and mixer and does the following:
1) if there's phantom power, use it to power on-board preamp for the mic and prevent phantom power from reaching the mic
2) if there's no phantom power, just pass the signal to the mixer

how would I go about building such a circuit?
>>
>>1678434
>you seem to know wtf you're talking about
lel
consider a small step down in functionality. if you allow for manual switching of pre vs. thru and you would be content with the box always blocking dc, then Pic related is a rough sketch of one way you could do that
>>
>>1678484
thanks so much anon! I'll try to build it this weekend.
>>
>>1678484
is that a relay?
>>
>>1678407
low-pass passes low frequencies which includes DC
so no
>>
>>1678426
I approve in principle, because I liek smol birbs as much as the next guy, but power + audio is a slightly unusual combination of functions

>>1678508
DPDT switch, it's a balanced line
>>
>>1678391
note that the cable had two 48V inputs
>>
If you have a stepper motor that uses say 3V through the coils and instead of 3V you use 24V and you pwm it to 3V will the torque be the same as if you use directly 3V without pwm?
>>
>>1678556
>3V through the coils and instead of 3V you use 24V and you pwm it to 3V


what do you think chopper drivers do? problem is controlling it fast enough and monitoring current. Not that it's impossible, just that it's usually better to buy the one-chip packages they sell for this sort of thing nowadays.
>>
>>1678560
I will of course be using a chip like that but my question is that if there is any difference in using say 12V power source vs 24V power source, as in will the 24V pwmed down to 12v give me double the torque than pure 12v would?
>>
>>1678561
>12V power source vs 24V power source, as in will the 24V pwmed down to 12v give me double the torque than pure 12v would?

Uh, no. if you buy a chip rated for a 24V supply, it will just change the duty cycle and frequency of the PWM vs. a 12V. supply based on your target current for the motor. all you'll do by increasing the supply voltage is decrease the RMS current you're feeding to the driver.
>>
>>1678561
The whole point of pwm vs current control is pwm you get the full torque of your max voltage but with less speed.
>>
>>1678561
steppers are just fancy coils breh, it doesn't matter, the current gets smoothed, so they only way to adjust torque is to raise or lower the average current
one trick with steppers to raise torque without raising current is to reduce micro steps from for example 1/32 to 1/16
>>
>>1678561
Voltage only affects the maximum stepping speed. Torque is dictated by current which is limited to what the coils can handle. If the coils can handle 3V without PWM, then PWM is just going to set the duty cycle to 3/V so that you get a mean voltage of 3V. 12V will give you a 25% duty cycle, 24V a 12.5% duty cycle, etc.
>>
>>1675224
the vast amount of ground connections over most of that circuit renders it impotent and uninteresting at 0V.
>>
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>>1678134
>>1678136
So i cracked it open.
Whats the verdict? is it isolated and safe to use?
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>>1678587
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>>1678588
One interesting observation, the supply is rated for 24V 5A
While the bottom one is rated for 24V 6A, are you telling me that one extra amp warrants those massive heatsinks while the 5A chink one doesn't need any of that shit?
>>
>>1678587
That's a nice line of LEDs
>>
>>1678572
Prime example of Randall's """"jokes""""
>>
>>1678595
You can actually select between 7 different voltage outputs and the led shows which one it is
>>
>>1678590
The bottom one can handle the 6A constant while the top one might be able to handle 5A for a few seconds, then fail.
>>
>>1678599
it's more of a selection of puns on the notation. the real chuckle is in the original mouseover
>>
>>1678602
I need to know i thought if it is safe to connect the device the shit one powers thorugh usb to my computer?
I have read horror stories of nonisolated chink power supplies where the second you connect an usb cable to your computer it burns the whole motherboard instantly because of some ground loop or something
>>
>have battery with JST PH female connector (on a wire pair)
>need to get power to something with JST XH male connector (on a PCB)
>can't find any XH-PH adapters
Do I have to remove the PH connector, strip the end of the wire pair, and install an XH connector on it myself?
Pic related.
>>
>>1678588
>>1678590
Not the worst thing, you know.
Output is not grounded though, this is why you see 100V there. Because you have anti-FCC capacitor there, between mains and output. It is OK, since it is low capacity.
I would run a jumper wire from ground to negative output, just to be safe
>>1678590
Top one looks like 3A power supply. Laptop bricks have similar size transformer and heatsink, and they are 19V 3A.
Keep in mind those OEM bricks have efficiency in 90's, and this probably 70-80%.
>>
>>1678644
yep. or splice the wires.
>>
>>1678079
>bought a device
its an industrial grade electric dragon dildo isnt it
>>
Where can I find OLED touchscreens above 5"?
Nearly everything I find on Mouser, Digikey, and RS are TFT LCD.
I value low power consumption, beautiful graphics, and cold tolerance.
>>
>>1678723
(also looking for >= 1920x1080 touchscreens in general)
>>
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If I want to make my own USB-A 2.0 cables, should I use something like this?
>Conductors: 4 (1 Pair Twisted)
>Wire Gauge: 26 AWG
>Shield Type: Foil, Braid (Aluminum; Copper, Tinned)
>Insulation: HDPE, PVC
>Voltage: 30V
and then shielded USB plugs and receptacles?
>>
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>>1678434

one way to do what you want is to keep the phantom power on one side of a transformer, and your sensitive electronics on the other, completely isolated from such insane voltage standards.
(the transformer i used here is marked Hammond 106905 0B5C but i seriously doubt that's an official part number.)
>>
>>1678758
Very nice design! Would it be possible to achieve something like this without the transformer? Transformers are too bulky...

But yeah, fuck phantom power! I've lost a bunch of mics because of it.... all it takes is for some retard to press a button or to just plug it into a board that provides 48V by default.
>>
>>1678753
you know you can literally go look up the usb specification right?

also why?

also, if you want to get pernickity, unless you want to pay like $5000 or whatever you can only make a usb compatible cable, not an actual usb cable
>>
>>1678777
>[...] right?
Yep.

>why?
Reasons.
>>
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Guys I got my new capacitors today, but didn't put them in yet. One reason is that the HF start is actually working, albeit very weakly and only once warmed up with the old caps showing no capacitance reading on the meter, and clearly with most of the oil leaked out (top left on the pic). Any ideas on why this would be the case? I still don't understand how this circuit is supposed to work or why I'm getting sparks (center of the pic) with bad capacitors. Also, based on the little circuit diagram, would working capacitors self-discharge through the transformer coils after the machine is powered off? If not, what is a safe way to discharge them? 5KV capacitor is rated "10 Amps" I think. Not sure if I should change anything since it's kind-of working somehow, but worried it might be hard on the tungsten spark points or transformer or something else running the way it is.
Thanks.
>>
>>1678777
Since you may actually have literal autism, I'll explain some things to you.
The "should" in:
>should I use something like this?
is not the same thing as "could" or "can"? I'm not asking if I can. I know the specs. I'm asking if I should.

You can try imagining that the comment said something like:
>I KNOW I CAN MAKE [THING] USING [PRODUCT X].
>SHOULD I USE [SOME OTHER PRODUCT] TO MAKE [THING] INSTEAD?
>IS [ARBITRARY PROPERTY OF PRODUCT X] SUB-OPTIMAL FOR CREATING [THING]?
>>
>>1678797
why don't you read the spec and find out
>>
What happens to the output of logic IC's like 74hc08d if they're left with floating inputs? Will the output switch on its own from hovering your hand above it?
>>
>>1678753
This sounds like the right way to do it + use a clip on ferrite bead
>>
>>1678807
Thanks, much appreciated.
>>
>>1678804
>Will the output switch on its own from hovering your hand above it?

why not try it? generally, with CMOS, you have to get within a millimeter or so of the pin. if its a Schmitt trigger input, you have to touch it. some will even oscillate without you around. the sluts!
>>
>>1678753
>PVC
ew, use silicone or vulcanised rubber
>>
>>1678865
>silicone
Silicone is fucking garbage. PVC is way better than silicone.
Silicone is impossible to strip cleanly. If you use sealant (silicone), it eats through insulation and corrodes copper with acid. Rips apart with some abrasion really easy.

PVC, rubber and fiberglass are only materials for insulation that matter. Oh, and PTFE, shit is good too.
>>
>>1678753
>should I use something like this?
no
>>
Please someone help me D:
I need to identify this component and how it works so I can emulate it.
I unfortunately don't have this component and it would cost like $90 to get one but I am hoping I can reverse engineer it without it.

It is this component labeled MAN with the orange highlight, bottom left.
>>
>>1678880
This is an image of the component itself, nothing physical to it that I can tell, like a slider or something
>>
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>>1678882
Another angle of it clipped onto the clutch cylinder.
It is probably swept with a magnet.

The electric throttle (7/51) has very similar 3 cable going to it, same figure 8 logo, and I have it.
I measured ohms, and
YE - WH open
YE - BN 50k ohms
WH - BN 6.8m ohms
The values didn't change when moving the pedal either.
>>
>>1678871
>Silicone is impossible to strip cleanly
>If you use sealant
We're talking about a USB lead, not hookup wire.
Anyhow plenty of people swear by using silicone as hookup wire likely because it doesn't make a horrific mess when soldering near it, but I haven't tried it yet. From what I've seen of silicone insulation (i.e. my soldering station cable and DMM leads) it's pretty durable, not sure what sort of wire you're talking about.

>>1678880
Is there a datasheet for the part?
>>
>>1678644
that's the best way to do it

>>1678653
that's the best way to do it

>>1678723
I suspect they're custom items and there isn't a lot of call for stock part numbers on the aftermarket

>>1678793
they wouldn't have put it there if it weren't necessary. less capacitance = less HF on the electrode. more capacitance = more HF on the electrode. you can hardly avoid improving matters by installing the new caps
>why sparks
those are overvoltage suppressors. they start conducting when voltage is high and stop conducting when current is low. they protect the transformers and/or provide the hysteresis required for the HF to swing in both directions
>safely discharge
if you're just removing them for replacement, short them by tapping terminals with a steel block (insulate yourself) and remove. it's a good precaution to wrap some fine-ish ~22-16AWG wire between the terminals of high-voltage capacitors to prevent soakage (the tendency for a capacitor to rise to a previous level of charge) and shock hazards while in storage

>>1678871
>using an ohmmeter's readings to test/identify parts
you're not from around here
it's a replaceable module in a proprietary automotive system driven by software, not some toggle switch. what those wires mean to the sensor and ECU are beholden to no standard. in essence, you're asking us to reverse engineer your car's ECUs so you can nigger your clutch back together
what you really need right now is help from someone who knows that model of car and its sensors
>>
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>>1678880
OK so progress,
I wired the throttle pedal to the clutch plug.
This made the ecu error code go away, so I believe I am on the right path, I will now take apart the pedal and see what's inside it.
>>1678893
lolno
>>1678907
>what those wires mean to the sensor and ECU are beholden to no standard
Wrong.
It's a simple electronic component. The diagram has the component icon that represents what it is. I'm just hoping someone sees the rectangle with an arrow into it and knows what that means.
>>
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Back
>>
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Front
Also important to mention i did not use pins 4-6 on this as the clutch sensor only uses the triple twisted wire set.
>>
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>>1678925
>component icon
dude, they're using an npn transistor to represent a whole ECU
anyway, to me the symbol says "potentiometer" but may or may not be exactly that, or just something kinda like that, or maybe some abstract analog sensor. I don't think you mentioned what code you were getting and what it meant
you could try hooking up a 10k linear pot of your choice and seeing what the ECU has to say about it. start at the brown end and work your way up slowly until the ECU shuts up, then temporarily secure it somewhere and try her on the road. NB driveability may suffer
to go further, you'll need to know specs like the output voltage range and how it corresponds to the pedal position (maybe a scan tool or ELM-type interface will help reveal that information), and then design a replacement variable voltage source based on something about the pedal position that you can adequately observe, anything from a microcontroller sensing the piston position capacitively at the cylinder, to a resistor/LDR by the pedal

>>1678893
Rat Shack used to sell Pic related to keep from overheating parts and wires when you soldered them. silicone is great for test leads and HV, terrible for general chassis wiring
>>
>>1678520
>power + audio is a slightly unusual combination of functions
Not necessarily. That chip is a combination of everything you need that isn't built into the microcontroller. Or, music player on a chip, just add your MCU of choice.
>>
What are the chances that one of you people is an expert with the DS2480B 1W bus interface chip?
This is a terrible datasheet. They list parameter 110 (LOAD) but never actually describe it like they do with the others. I couldn't find info on this anywhere.
>>
>>1678804
It can. You shouldn't leave sensitive inputs floating because the pins act like little antennas and can waste power if they cause logic transitions. As you probably know there is RF-induced noise damn near everywhere.
>>
>>1678945
Oh I just need it to think the clutch is fully depressed so it starts. The engine is currently just laying on the ground and I have the entire wiring harness out of the car and on a bench where I'm trying to get it running standalone.
It won't be going back in the same car so I don't care about clutch position. Not sure why it has to be so autistic about it anyway.
Following the traces on the pedal board, the brown wire does a whole lot, and the white/yellow wires seem to do nothing, just go down to a dead end trace. Unless the vias tee off on an internal layer but it really doesn't look like it.
At this point I'm probably going to just get the part. But hopefully from a junkyard.
>>
>>1678893
>Anyhow plenty of people swear by using silicone as hookup wire likely because it doesn't make a horrific mess when soldering near it,
It has one nasty thing about it. Silicone insulation is too soft, and cable will crack because of it.
If you need flexibility, PTFE (MГTФ) is just best thing. It is super flexible. But because of it you need some sort of relief thing near solder joint. . Won't melt too.
>From what I've seen of silicone insulation (i.e. my soldering station cable and DMM leads) it's pretty durable, not sure what sort of wire you're talking about.
On tools I believe in rubber, though on mulitmeter silicone makes sense, just because I have burned PVC wires once. And Teflon with proper insulation would be too expensive.
>>
>>1678981
ahh
wew, that's pretty autistic. it's allegedly a safety feature preventing unexpected torque at the wheels when starting (and saving the jobs of 17-year-olds at the oil change drive-thru who think manual trannies are something from gender studies). mine just uses a good old momentary switch on the firewall, which happens to be broken and jumpered across at the moment

>>1678954
mostly considering the isolation aspects of it, that you wouldn't want the one to bleed into the other, but a portable music player is probably not targeted at people who would notice, let alone describe noise they noticed
>>
>>1678989
>Silicone insulation is too soft, and cable will crack because of it
The silicone USB cables I've seen use a braided metal shielding that I imagine gives it a fair bit of tensile strength.
>>
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This isn't a hard project at all, but I'm mildly proud of thinking of it
I found a cheap ($5) speaker at Goodwill that was actually decent quality and decided to bring it home
I also had a cheap old bluetooth speaker (an HMDX Jam Classic if you care) at home
I got curious and wondered if the bluetooth base could drive a regular speaker, and it turns out it can.
So I removed the original speaker and replaced it with a short length of speaker wire, and ran that to the goodwill speaker (standard speaker hookup, two wire clamps) and it actually drives it at a reasonable volume (I only listen to it in my room, so it's not a big deal if it can't go super loud) and sounds really good (compared to the tiny driver it had originally)

tl;dr I made a speaker into a bluetooth speaker by gutting a cheap bluetooth speaker
>>
Does anyone know why the transformer in the post >>1676056 is shorted?

Also why does the resitor exist? Doesn't the voltage of the source divide between the resistor and capacitor almost exclusively to the capacitor?
>>
>>1679063
I mean if it works, it works. Enjoy your speaker.
>>
>>1679088
It's not shorted, it's just that one side of both windings is common to the circuit. The circuit will work as well if the secondary were isolated.

As for the capacitor, it's not for a divider. The cap charges through R1 up to the full battery voltage. When the switch closes, the energy from the cap is dumped into the transformer primary. As long as the switch is closed, the cap and the transformer primary form an LCR resonant circuit and it "rings" as energy bounces back and forth between the transformer and the capacitor. This high frequency ringing current induces a high voltage in the transformer secondary.
Once all the energy is lost to resistance, it stops ringing, a small direct current flows through R1 through the transformer primary and doesn't induce any voltage in the secondary. You have to release the switch and let the cap charge again for another shot.
>>
>>1679093
>The circuit will work as well if the secondary were isolated
Thanks for explaining.

I also get your explaination about how the circuit works, but why add the R1 then at all? Couldn't you just not use it? Or does it protect the source or something from the "bounces" of the LCR circuit?
>>
>hey guys where can I find info on VC(O,F,A)s?
>those are baby elementary circuits retard
>look up elementary analog electronics textbooks
>literally none of them have any info on VCO/VCF/VCAs
>not even The Art of Electronics mentions them
wtf not based :(
>>
And that's fundamentally it.
>>
>>1679094
>why add the R1 then at all?
Prevents you from shorting the battery. 8Ω is not the resistance of the winding, that's much lower. Given the values of the circuit I wouldn't expect much 'ringing' either, certainly no 'high frequency'. More like a single aperiodic process.
>>
>>1679122
is it real or is it greentext
>>
>>1678865
>>1678871
>>1678893
>>1678945
thank you for writing about this. currently leaning towards silicone wire for some applications.
>>
>>1679175
in my research I found
https://www.youtube.com/watch?v=7QpfTa5mEwQ
where a guy simply squeezes some silicone wires for 6 mins
>>
>>1679154
>Prevents you from shorting the battery.

I thought the capacitor would "load" until it reached negative the supply voltage and from there on no current would flow until it was discharged by pressing the button?
>>
>>1679191
Without the resistor you would directly connect the battery to the low-Ω input of the transformer as long as you push the button.
>>
do you guys like my inverter circuit
>>
>>1679207
What does it invert and what for?
>>
>>1679217
it inverts dc current into a stepped sine wave
it's designed to be as terrible as possible
>>
>>1679206
thanks for clarifying, that makes sense, you'd add the resistor depending on your power source and to prevent those temporary shorts.
>>
now we're talking
>>
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I made this railway signal with an ULN2003A and LEDs and a small program that loops though all the indications.
Main signals are indicated as solid colours, while the distant signals alternate between 50% and 100% intensity at 1 Hz. In reality the intensity is 10% but I didn't find a way to dim the LEDs so much yet.
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>>1679063
>This isn't a hard project at all, but I'm mildly proud of thinking of it

you replaced a small tinny speaker with a larger better-sounding speaker. it's like being proud of the idea of replacing an AA cell with a longer-lasting C cell.
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>>1679253
neat
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>>1679243

that only works in a simulator. in real life the waveforms will not be synced so you'll get chaos waveforms.
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I took apart a TRRS cable known to be shitty.
some questions ...
what is the term for thin stranded copper wires mixed with PVC fibres like in this pic? referring to each of the individual conductors.
does the between-conductor insulation look like regular PVC fiber strands?
are the copper strands around the white mic wire called spiral shielding specifically?

this cable in particular picks up GSM disturbances (via mic) when in calls.
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>>1679284
more questions! is mixing polymer fibers with stranded conductors like this (instead of pvc-coated strands) mainly a cost thing or more a matter of maintaining flexibility / keeping the cable thin and still durable?
aren't they a royal pain to solder?
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>>1679267
It already sucks in the simulator, the shorter waveform goes out of phase almost immediately and fucks everything up
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>>1679253
neat, what country's aspects are those?
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>>1679284
>>1679288
It's a kind of Litz wire, done here just for flexibility. the plastic fluff isn't for insulation, it's just to fill up space while being flexible, the enamel coating on the wire does the insulation. The wrapping around the mic (or video) is a kind of spiral shield, cheap to do, pretty flexible but not amazing.

Soldering the coated wires isn't too tricky, get soldering iron reasonably hot and the insulation just burns, can leave behind some black crap so clean the iron tip.
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>>1679122
no, no, look up baby analog COMPUTER books, which are actually high-school analog electronics books with some college math thrown in for fun. analog synths are exactly that

>>1679178
this ASMR fad's getting way out of hand

>>1679223
10/terrible

>>1679063
yo dawg I heard you like bluetooth speakers

>>1679293
add sync
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>>1679341
>analog COMPUTER books
ok that makes a lot more sense. It's a shame all these books I'm turning up are all pre-1980's

>add sync
as soon as I figure out how, I will.
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>>1679324
Thanks! Very useful information.
I frayed the wired and burned away the insulation, then soldered the wires together. Threw some electrical tape on the individual wires (in lieu of shrink tubing) and the cable works fine.
I'll buy a new cable with foil + braid shielding to prevent the GSM issues.
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>>1679352
yeah, the digital computer really did a number on the analog computing world
a small cap (~1nF) coupling one output into one of the other osc's bases is worth a try. you don't want to trigger the other osc entirely with it, just give it a little push so it switches a bit early
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>>1679373
I'll give that cap a shot. The only way I've been able to change the phase of the oscillators so far has been to make minute tweaks to the capacitance of the caps on the transistor bases which I know is completely untenable for an actual design. Not to mention, as is the nature of that kind of oscillator, they start off randomly out of sync as well.

I was thinking of some way to implement a feedback system but have no idea how to variably change capacitance. This would be a terrible design in the real world.
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>>1679381
not to mention I have no clue how this would even react to having a load attached to it
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>>1679381
https://en.wikipedia.org/wiki/Varicap
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thread. ohm. new.
>>1679331
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>>1679394
fuck off, it's barely page 3
cool thread pic tho
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>>1679387
but mostly useless in the audio range

>>1679381
>feedback
you'd vary the resistance, or alternatively, the current those resistors are meant to supply. variable caps of the size required for audio oscillation can be hard and expensive
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>>1679412
I'll take this into account next time.
thanks
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Is it possible to solder on spray painted pads? Will the rosin in the solder clear that shit out? it's acrylic spray paint
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>>1679678
PMMA burns at 460 °C. Loss of important structural properties before that. The temperature of the soldering tip + the acids in rosin should be able to break it down enough to get a proper surface.
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>>1679699
>PMMA burns at 460 °C.
No fire required, it melts at 160°C.
https://www.google.com/search?q=pmma+melting+temperature
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>>1679317
That's the newest burjo börö system. From left to right
1. stop
2. proceed
3. proceed 35 km/h
4. proceed, expect stop
5. proceed, expect proceed 35
6. proceed, expect proceed
... and so on.

Single white is "proceed carefully", single blue is "no signals". (I didn't have any white/blue leds at hand so I used green/yellow instead).

https://en.wikipedia.org/wiki/Finnish_railway_signalling
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>>1679715
>it melts
Sure. That doesn't mean it's not still on the surface of the material preventing proper metal exposure and connection. Residual plastic and pigments will remain even after attempting to wipe it off. Given the polymer's shit binding capabilities to metal, it will most likely bind better to the rough and oxidized surfaces (feel free to look up enhanced adhesion of PMMA:metal oxide interfaces). The surest way is to burn it off and scrub/flux the surface.

>google link
why? it's a thermoplastic. of course it melts.
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>>1679678
Direct soldering works with the clear acrylic spray used for water protection of boards. You can also remove it with acetone if necessary.
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>>1679732
nice, hadn't seen that system before
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>>1675224
Please help /ohm/, I'm dumb. I barely know anything about electronics, I got a Toshiba TV for free but it makes a really horrible high-pitched whine. I narrowed it down to a specific part, but I have no idea how to source a replacement (or really how to install, that part I figured I'd look up a similar tutorial), only that I need resisters and some normal tools to do the work, but I've got those already.

Even just a site recommendation would be a life saver.

[Manual]:
https://www.manualslib.com/download/699581/Toshiba-Md13q42.html
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>>1680392
>how to source a replacement
enter some of the text you have selected in red in a search engine of your choice
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ive spent half an hour reading about mosfets and i think i get it now
from what i understand source and drain get shorted when theres a voltage between gate and body
why is body connected to source?
is there any real benefit to doing that because its much harder to understand
it also prevents a single mosfet from swithing ac loads because it forms a diode betweem source and drain
also why is it done with a p+ area?
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>>1680415
https://www.eewiki.net/pages/viewpage.action?pageId=49414403
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>>1680392
Try rewinding it? Don't forget to count the number of turns and respect the gauge and insulation.

>>1680415
For the FET to turn on, there must be an electric field through that depletion region of the semiconductor. The body is connected to the source in order to turn the body into the other side of a capacitor made with the gate. Hence why the threshold voltage is measured as a voltage V_GS; the potential between the gate and source. Otherwise the MOSFET would be unpolarised. See the construction of a JFET, which is unpolarised, and uses the constriction of the depletion region from two same-polarity gate electrodes on either side.

You may be able to get MOSFETs that require an external body connection, which would be potentially usable in AC, however to turn them on you'd need to drive the gate above and below the peaks and troughs of the AC waveform (like you would a high-side N-FET or low-side P-FET except constantly changing), and I imagine they'd require a much higher gate voltage in order to get a electric field of the same strength. In other words, a huge pain in the ass when you could just put two MOSFETs together in series in a single solid-state-relay package, with an opto-isolated gate for good measure.
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guys,
I've been repairing various old amplifiers and tape decks and I often see this metal finish on the inside of the chassis.
What is this finish called? How is it achieved?I don't think you see this finish on new equipment anymore...
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>>1680927
>I don't think you see this finish on new equipment anymore...

https://en.wikipedia.org/wiki/Plating#Cadmium_plating
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>>1681256
thanks anon! damn... had no idea it was toxic! I have to be more careful now.
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>>1681256
>>1681305
lel it is only potentially toxic for the workers who may be exposed to the fumes during the manufacturing process like smelting etc, the finished product even though it may have some toxicity >0 but far from dangerous levels unless you eat it or something.
also, type cadmium plating into google images and you will see lots of bolts and nuts and connectors that are widely used literally everywhere.
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I want to add a flyback diode to pic related (left side) and I see it on the diagram but, where do I -physically- add it?

Between the transistor and the motor? Between + and the transistor?
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>>1681637
for more info, motor is a dc brushless fan (but made in china so is why I want a diode in just-in-case). going with the left side diagram (NPN transistor)
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>>1681647
Those things have their own somewhat delicate switching circuit that runs off a hall sensor, so there's almost no way for them not to have diodes in there already. If you still want one, it really doesn't matter where it is, if you have a PCB of some kind I'd put it on there (i.e. where the transistor is mounted) just because it's probably easier. The resistance of the wires is entirely inconsequential compared to the effective resistance of the diode.
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MIGRATE TO THE NEW THREAD:
>>1679331
>>1679331
>>1679331



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