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/diy/ - Do-It-Yourself

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1610590 No.1610590 [Reply] [Original] [archived.moe]

busted thread: >>1606134

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

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

>Project ideas:

>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:
NI Multisim
iCircuit for Macs
KiCAD (pcb layout software, v5+ recommended)

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

>Related YouTube channels:

>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.

>> No.1610592
File: 136 KB, 907x832, 1555094059651.png [View same] [iqdb] [saucenao] [google] [report]

this thread's digits brought to you by the AD590 two-terminal temperature sensor

>> No.1610598
File: 55 KB, 500x375, 6284a3051b273d78d2a04c6c12383c22.jpg [View same] [iqdb] [saucenao] [google] [report]


I'm about to have work done on my workspace's roof so i't s the perfect opportunity to remodel/restructure.
I'm currently looking at an empty 12m x 5m room, what should I do with it? Any cool workshop pictures I could use as inspiration?

>> No.1610602

You know how on arduino there are rx and tx pins on serial? If i want pull rx high do i have to use a resistor to limit current, or can i hook it directly to 5V?

>> No.1610605

I want to fix an old guitar speaker that I bought at a swap meet & got kinda burned on. What I did not know at the time was that the speaker had issues, and the voice coil was damaged. I can not find a voice coil that is an exact replacement, so I was thinking of buying one that roughly meets the size requirements, and then modifying it to meet the right size. The one question that I have is how does the width of the coil winding effect speaker performance? All the voice coils that I find that would fit have a slightly wider winding, and I want to know if that would impede with how the speaker performs in any way.

>> No.1610607

no appreciable current flows into CMOS digital inputs whose levels are within the rails anyway. if you want Rx high always, just wire directly to Vcc
no, Vcc. if your arduino has a 5V Vcc then you can treat them the same, if not, then you can't
all that said, you could just switch on the pullup for that pin in code, no?

>> No.1610620


since the Rx pin can be programmed for various purposes, it's possible you'll try out a program that makes it an output, and if it's connected to Vcc, you might get a short. a cautious arduino-fag would use a pull-up resistor.

>> No.1610632
File: 69 KB, 1599x819, IR_Communication_2[1].png [View same] [iqdb] [saucenao] [google] [report]

I see.
I am trying to hook up this serial communication.
I assume the transistor is used to modulate the signal, do you think it would work with a mosfet instead? probably not right? since it would be mondulating as sort of a square wave and not a sine

>> No.1610636

>mondulating as sort of a square wave and not a sine

wat sine? this is all digital: 40Khz signal being modulated by the serial stream.
the BJT is simply turning the LED on or off fast, so any FET will work exactly the same as the BJT assuming it's the variety that turns ON when you apply a positive gate voltage.

>> No.1610639

works fine with a MOSFET
different members of the arduino family use different logic levels. some newer duinos run at 3.3V logic even at 5V supply. check your board's documentation and wire Rx to whatever the correct logic-high voltage is

>> No.1610640

gimme some project ideas - i feel like designing a pcb. I want to do something fun and challenging

>> No.1610643

DDR2 or DDR3. mass delay-matching is always entertaining

>> No.1610645

something a little easier lol

>> No.1610648

Audio Player
Have a uC read raw data (PCM) from a file on an SD card and push it through a DAC to play musics.
Bonus points for at least 16-bit 40 kbps quality

>> No.1610656

>not supporting mp3 or MP4 AAC
I mean, there are some upper-end micros with adequate RAM and flash on board that you could build libav and link a simple directory enumerator and shell with them. and then there's that BeagleBone SiP

speaking of, a BeagleBone PC-in-keyboard might be a little easier and more fun. or, more generally, something you could actually use pretty often and would like to enclose or conceal inside some other small form factor of your choice. maybe a Bluetooth two-way makeup mirror idk

>> No.1610659
File: 420 KB, 1189x845, 1536526010395.png [View same] [iqdb] [saucenao] [google] [report]

besides, meandering traces are totally relaxing

>> No.1610667

>Listening to compressed music

But its actually easier to just play PCM data than have a uC try and decode it. The Microchip dsPIC33FJ64GP802 is a 28 pin uC, runs at 40 MIPS (internal clock) and can play 16 bit PCM data. Wire up an sd card, pull the bits into the uC with SPI, use DMA to send it directly to the internal DAC, output to opamp of choice. Boom, music, and it still has tons of headroom for controls, display, even light DSP for effects.

>> No.1610668

Okay. I was actually wrong. It was my shitty wiring arcing due to higher vibrations at lower speeds. I wonder how ECU didn't blow up...

>> No.1610681

I love wiggly traces, it's such an engineering solution.
>hey this signal is off by x nanoseconds, should we buffer the input with a cap in silicon, extend the timing windows, what
>just make the wire longer


>> No.1610717
File: 20 KB, 633x755, traffic signals.png [View same] [iqdb] [saucenao] [google] [report]

I'm trying to come up with some circuit ideas using the 4017 counter IC. Made this simulated toy circuit for controlling a traffic signal. The idea is to use this circuit with a microcontroller to control many (or all) traffic signals of an intersection.

It works by first setting the "Enable" input high, followed by a "Reset" pulse and then clocking required number of "Data" pulses into the 4017 counter IC. The aspect is changed after setting the "Enable" input low. The outputs 1..4 of the 4017 select a different light combination.
- 1 clock pulse: red,
- 2 pulses: red+amber,
- 3 pulses: green,
- 4 pulses: amber.

There's also a fail-safe watchdog function. If the "Enable" signal hasn't changed after a certain time period, the 4017 counter is reset to "0". This starts flashing the amber light, indicating that the traffic signals are not functional.
The current version is kind of crappy as the lights can't change simultaneously. Would need to have some kind of "strobe" signal.

>> No.1610721
File: 15 KB, 880x443, signal3.png [View same] [iqdb] [saucenao] [google] [report]

Here's the internal connections of the controller blocks.
In this simulation I'm using a shift register to implement the fail-safe counter. However I think in a real circuit a 555 timer could be used instead. Falling edge on "Enable" clocks the output D-flip flops and transfers the 4017 count value to the outputs.

>> No.1610722

Once i etch and solder my pcb, what can i do to prevent the cuprum layer from degrading?

>> No.1610731

Cover it in some water-tight material, like elmers or plumbing glue

Also, call it copper

>> No.1610733

like some common low born serf? no thanks

>> No.1610744

either manually tin it with solder or use liquid tin

>> No.1610769

>he doesn't into FLAC
>internal DAC
y tho, I2S interfaces are pretty common on 32-bit micros and stereo 16-bit I2S DACs can be alibayed for like 15 cents. ye olde ubiquitous 32F103 would be just fine here


you should have bought a rail of 'HC595s instead
>The current version is kind of crappy as the lights can't change simultaneously. Would need to have some kind of "strobe" signal
you could also be crafty on the MCU end, asserting enables 1-4 data cycles before the change and releasing them all at once
or you should have bought a rail of 'HC595s instead

>> No.1610772

I bought a Bench power supply that's old. Like about 20 years old. (Sat in a hoarder/seller's place for years)
Every time I try to drive the voltage higher than ~5.5V it starts making clicking noises and the Voltage drops by 75% and it cycle backs. Works like a charm under that.
I'm replacing the El.Caps with new ones even though they tested fine ~10%.
Diodes, Resistors & Pots are all fine.
Should I also remove and test the Mosfetts & Transistors?
There's also two Mechanical relays no longer manufactured.

>> No.1610776
File: 985 KB, 1152x3180, Testing.jpg [View same] [iqdb] [saucenao] [google] [report]

Pic related

>> No.1610786


notice how the transformer has a whole bunch of windings. what it's doing is switching from one winding to the next as you increase the output voltage. (this keeps the output transistors cooler by having a smaller input-output differential.) it sounds like one or both relays are bad/dirty. replace 'em.

alternately, you can remove the relays and hardwire the winding which gives the highest voltage across the huge filter cap. you can keep the transistors alive by not letting them get too hot.

>> No.1610788

>he doesn't into FLAC
Still have to process the data, raw code means more free CPU time. Plus space is getting CHEAP these days, praise the NAND gods!
>internal DAC
internal DAC is just a bit faster, no need to interface to anything external. Bust out some DMA channels for internal processing. Saves some space too.
I'm working on a 32-bit DAC player that uses I2S interface to an external DAC from the DSP. Each to their own, they both work.

>> No.1610799

Thanks you so much I'll get working on those relays.
Makes sense as to why the Transistors are not heat-sinked like I've seen sometimes on recent ones.

>> No.1610806

holy shit lmao

That's really neat looking, I wonder if any hobbyists have attempted to make such a thing?

>> No.1610907
File: 27 KB, 450x450, d331b890-2226-427a-9146-c7baa42faf4f_1.5d568d85a8f86aa988ec1b2ad47702c4.jpg [View same] [iqdb] [saucenao] [google] [report]

I want to make a cheating scientific calculator.
>take calculator like pic related
>remove its blob chip
>design a PCB with micro, LCD controller and SD card slot.

The question is, where can I get such LCD controller, or I'm better buying thicker calculator and replacing its screen with pre-made 16x2 with I2C bus?

>> No.1610909
File: 9 KB, 207x243, download (6).jpg [View same] [iqdb] [saucenao] [google] [report]

I think this would be more suitable, has more space inside.

>> No.1610923

Cheating scientific calculator? What?

Like something you can have regurgitate information from an SD card?

>> No.1610961

A micro with a big enough pin count could be its own LCD controller, or just use some latching shift registers like an edgy dude.

>> No.1610975

So using an acrylic spray for cars should work on the pcb?

>> No.1610981

Yeah, normal spray-lacquer/clearcoat should work. But watch out if you need to have some level of heat-tolerance that wouldn't be needed on a car exterior.

>> No.1611005

Yeah i am retarded, the modulating signal is at the gate so it's a simple square wave i just realized.

I tested it and it works great.
I want to add this as a communication for lots of my IOT devices and am deisgning a pcb for it and will send it over to chinks to make it for me.
Do you think the schematic provided is fine as is or should i add some magical caps or resistors etc somewhere for increased stability?

>> No.1611012

Projects planned with parts ordered and received for them: 25
Projects with parts on the way: 4
Projects actually finished: 2


>> No.1611025

Wow that's like me, except only like 15, 0, 1

>> No.1611035

That would be pain in the ass. Specialized ICs exist, why not make use of them?

>> No.1611044

Why don't you cheat by putting the information in your own memory instead?
You can't get caught looking at that

>> No.1611053

Well if you were short on room, like the others were implying. That sort of specialist IC usually needs to be ordered from someone like DigiKey or Mouser, who I've never ordered from because of their shipping costs.

I'd prefer printing a counterfeit drink bottle sticker with answers written where the ingredients should be, and fill the bottle with water. Not that I'd ever cheat, as it incentivises the tests to be made more difficult for the next year in order to get the same pass rate. Assuming its a low-volume test (doesn't have thousands of people sitting it) that is.

>> No.1611058

LCDs like that have multiple backplanes and are quite difficult to drive. You really want a LCD controller for that.

Since space is an issue, he should look at MCUs that have an integrated LCD controller.

>> No.1611059

I'm designing a PCB for a project. Under my PCB are going to be two rotating neodym magnets. How badly is it going to affect the circuit? The PCB is only supposed to connect a two sensors with a Pi Zero W.
Is making a ground plane enough or are there different methods to shield?

>> No.1611064

I did a bit of research into this, because I had the epiphany that a calculator is just a computer, and i could therefore put whatever i wanted to on it.

i considered ripping out a calculator shell and putting in a raspberry pi type thing. there's a forum where people develop programs for the TI line of calculators, and one guy there is basically making a calculator himself, and has plenty of information on it.

the ultimate thing that stopped me was two fold. 1, wiring the buttons up to something is apparently very difficult. there's some sort of proprietary harness that texas instruments uses, and you'd need to build something that would allow the keypad to interface with the raspberry pi.
2, i was unsure how to mount the screen in the TI chassis without having to extend the depth or width of the case.




>> No.1611067
File: 125 KB, 562x954, stmcalc.jpg [View same] [iqdb] [saucenao] [google] [report]

I need to go back to my custom calculator project.
I used a cheap Casio clone. To interface with the keyboard (which is connected through a glued on flat cable) I cut off the original controller, scratched off the solder resist, and soldered wires on to it.

>> No.1611068
File: 482 KB, 2560x1440, 26lcd3.jpg [View same] [iqdb] [saucenao] [google] [report]

pic related. i'm pretty sure there isn't an easy way to make the cheating calculator you want to make... which is unfortunate, because the TI84 has been around since 2004, has 24 KB of accessible memory, and still costs 100$. it's nuts.

>> No.1611069

You could easily get a few mV induced in your circuit with strong Nd magnets, you'll probably want to minimise the change in flux. Ideally put opposing current paths as close to one another as possible, or otherwise use something equivalent to a twisted pair or coaxial setup such that all the change in flux cancels out. A sample circuit diagram (and the positions and orientations of the magnets) would be a good thing to post if you want some less vague criticism.

Can't you just test which button corresponds to which wire via trial and error (logic analyser might help) and feed them into a USB keyboard controller IC?

>> No.1611073
File: 111 KB, 402x831, na113Ro.png [View same] [iqdb] [saucenao] [google] [report]

folks on the cemetech forum mention using a microcontroller (MSP430) to relay the keypresses. The pi is apparently slow at handling the keyboard matrix on it's own, and would waste a lot of time.


is a french project working on this sort of thing, but no clue how their development is going.

a dude on the cemetech forums went through the trouble of making a PCB rather than interfacing with the one already in the calculator, if that's any indication. Obviously, you'd want the keypad to look and feel legit, but it seems like a real motherfucker to pull off.

>> No.1611075

Reasonable enough, for that kind of multiplexed(?) keypad the only other method is with a few shift registers. But I think either way you'd need external transistors since you want to pull up the rows and pull down the columns, if my brain is working correctly.

>> No.1611077
File: 30 KB, 466x384, keypad.gif [View same] [iqdb] [saucenao] [google] [report]

bear in mind i'm not the original asker, i just think it's interesting because i thought about doing the same thing.

this is the schematic for a casio prism, and the TI layout is pretty similar.

>> No.1611079

An extra microcontroller is a bit of a waste.
They make dedicated ICs for key matrices.

>> No.1611080

This is probably true.

>> No.1611082

it does seem a bit superfluous. surely it would be better to use a dedicated IC since the only purpose of the microcontroller is just matrix math before handing off to the pi.

>> No.1611085
File: 17 KB, 1482x563, schematic.png [View same] [iqdb] [saucenao] [google] [report]

It's going to look like this more or less.
My plan is to place the circuitry as far away as possible from the magnets.
What you mentioned sounds good. But isn't capacitve inductance going to become an issue when placing traces too close to eachother? I suppose that's going to be the lesser evil though.

>> No.1611086
File: 385 KB, 1536x2048, IMG_20190516_134313.jpg [View same] [iqdb] [saucenao] [google] [report]

I just came back from work, i don't have to work the next 3 days and am about to enjoy a delicious lunch in my underwear, while exploring this chinky logic analyzer that some anon here recommended to me.

I paradise exists, this is it.

>> No.1611091

I have no fucking intention remembering stuff I will never use.
Well, you can get IC on Ali Express.
Also, bottle trick is known and I got caught not even once with that.
Writing shit on calc is much more efficient, but that sliding cover can't fit much information.
Interesting. I want to keep stock chip though.
Graphical calcs aren't allowed.

>> No.1611093
File: 435 KB, 550x800, TI-Nspire_84KBD_BLY_PCB.jpg [View same] [iqdb] [saucenao] [google] [report]

the TI84 keypad interfaces with the switches on the board, and i was thinking maybe you could use some other sort of "grid of switches" underneath to intercept keypresses.

however, i just found this:

a drop in keypad for the TI-Nspire. It pins out in a convenient location, and might be way easier to tap into with some sort of ribbon cable, rather than the tiny array on the default TI84 board.

maybe even... easy...

>> No.1611095

wait, what problem are you trying to solve by cheating? if you can put programs into your calculator, you can put text into it.

>> No.1611098

Nah looks like you'll be fine. No looped traces near the magnet at all. You could do the calculations with Lenz's law if you can measure the magnetic field strength with an analogue hall sensor, but considering I couldn't get an appreciable voltage (i.e. less than 1mV) from a bike computer magnet spinning at top speed half an inch away from a a 220µH inductor, I doubt you'll have any issues.

Oh hey, mine arrived too. I probed about a bit with it with Pulseview, which works great, except for the fact that my analyser's probes go from 1-8 not 0-7. Might make my own label to amend that, and of course change the leads around such that 0 = black, 1 = brown, 2 = red, etc.
In some ways the 1-8 made more sense since it left the black wire to be 0V, but fixing a sticker is much easier than worming into the hardware.

>> No.1611099

Shitty memory, and I'm nervous fuck, which makes me forget fucking everything.
And by writing I meant writing with pencil on plastic. I just want level up this.

>> No.1611101
File: 1.74 MB, 1397x2154, cheatmode.jpg [View same] [iqdb] [saucenao] [google] [report]

program as in does your calculator have a program function. input your notes as a program.

>> No.1611104

We are not allowed to have programmable calcs. Otherwise it would be easy

>> No.1611107

>no smart text wrapping

>> No.1611115

>:P emoji

>> No.1611116


>> No.1611141

it'll work, sure, but the transmit side has a minor power efficiency issue that you could address in software just by stopping the square wave out when not actively transmitting

is that your year-to-date?

>USB keyboard controller IC?
iow, a microcontroller

y tho, when you can simply tri-state the outputs almost as easily as you can set them low or high

yes, but they also are generally sold in larger packages than micros (for shitty chink-television-tier 1-layer boards), and most have bizarre host communication protocols (like I2C with no address byte)... oh, and might not have the rollover to handle all those shift keys

>> No.1611205
File: 40 KB, 1086x465, signal.png [View same] [iqdb] [saucenao] [google] [report]

I have a digitized signal that looks like pic related.
Whats the term for those 1LSB spikes and what would be the propper way to find the location of the local maximum?
It seems like something so basic but I'm having a hard time finding information since I don't know the propper terms.

>> No.1611221

Not sure of the spike names, perhaps accuracy? I'm assuming you're reading a DAC output? Some DACs have an accuracy rating that pretty much says its Vout is accurate within 1bit or something of the digital value.

Need some more info on what you're doing exactly.

>> No.1611229

quantization noise?
a simple weighted-sum low-pass filter in software will help a lot, but if you want to try to accurately measure <1LSB try adding a small (1 LSB p-p) high-frequency (<1/2 fS) sine or triangular wave (aka dither) into the input signal before the ADC

>> No.1611233
File: 5 KB, 610x277, signal_full.png [View same] [iqdb] [saucenao] [google] [report]

I'm using this data aquisition module: https://www.meilhaus.de/en/redlab-204.htm
I'm sampling a voltage at 250kS/s for 0.5s = 125000 datapoints.
I use LabView to work with and visualze my data. I get the data as an array of floating point numbers.
I made a sketch of my full signal. I want to find the timing of the local maximum and minimum as illustrated.
the smal peaks in >>1611205
fill my peak detection with false positives.

>> No.1611255

I see only 18 counts (~4b) of amplitude. I think you need a lot more bits

>> No.1611260

It's the verry peak cropped out so you can see the bits.

>> No.1611261

anyone know how pin symbol is called in kicad? i need to place some simple pins onto my pcb and can't find them in the library

>> No.1611262

if I do a mooving average I still end up with with multiple, though smaler peaks.

>> No.1611264

You mean a normal header?
In the schematic editor they're just called Conn_....
The footprint would be like: something header something 2.54mm

>> No.1611281

in the schematic editor? try Conn_01x01 or search for test point

if you don't need that 4us resolution, could you oversample? also there are other filtering algorithms you can try, maybe a sinc filter would be best for precisely locating something like a peak?

>> No.1611298

thanks, thats perfect

>> No.1611667
File: 1.62 MB, 3264x2448, 1-2.jpg [View same] [iqdb] [saucenao] [google] [report]

Oh man, my uni has a bunch of scopes and function generators just sitting in the physics lab, no clue what they're going to do with them. Here's the front, they've got everything from those 20MHz ones on the left, to most of those middle 50MHz ones, to 3 or 4 100MHz ones, all Hitachi.

>> No.1611671
File: 1.85 MB, 3264x2448, 2-2.jpg [View same] [iqdb] [saucenao] [google] [report]

From the back you can see more of the Hitachis, as well as some stranger looking function generators, as well as an ancient Telequipment 10MHz model. Looked up a datasheet for it and found one, on the Radio Museum site. Is it bad that I want the 10MHz model more than the 100MHz model?

>> No.1611698

you should ask about them.
Analog scopes are going out of style fast- who wants to train students on outdated equipment?
if you make the acquaintance of the right people, you can get loads of free equipment from a university.

>> No.1611725

>- who wants to train students on outdated equipment
Hahaha i see you've never been to college

>> No.1611727

Well I find them easier to learn the ropes on, not to mention this lab rarely requires anything over 20MHz, but I can certainly see where you're coming from. I'm unsure if they're dumping them or if they've just got them out for recalibration. Already got a little swag from my uni (digital logic trainer), so I guess I'll ask about the scopes after the weekend is over.

I see you've never been to a good college.

>> No.1611754

If i have a relay rated for burger voltage but spec says that absolute max switching voltage is 250v,can i run it on 230v longterm?

>> No.1611757

250VRMS or 250Vpk or 250VDC? Because 230V AC goes up to 325Vpk. DC also needs to have better open isolation in order to cut arcs that would otherwise be cut by the 0-crossing of AC.

>> No.1611759


>> No.1611765

Doesn't really say.
Just says 250Vac

>> No.1611766

no, you can only use it for 125V
250V is a stress rating and prudent engineering dictates that one stay a safe distance from it

>> No.1611767

then that's RMS

>> No.1611769

i can't find any two coil relay on ali that is 230V rated
all they sell are those regular blue ones everywhere
damn chinks

>> No.1611771

Tried searching for 240V and 250V?

>> No.1611773

yes, but all i can find ever are single coil relays
two coil seem to be unicorns

>> No.1611776
File: 145 KB, 1020x773, Clipboard01.jpg [View same] [iqdb] [saucenao] [google] [report]

Yay! My masterpiece if finally finished. My first ever pcb.
Can't wait to try and make it for the first time as well.

>> No.1611778
File: 2.76 MB, 1280x720, 1535066216086.webm [View same] [iqdb] [saucenao] [google] [report]

a two-for-a-penny CAN transceiver: the humble B5819WS Schottky diode
webm related: the sender with the key pad sends settings to the bus. both receivers hear the settings changes and act accordingly

>> No.1611779
File: 826 KB, 512x326, 1537276999749.webm [View same] [iqdb] [saucenao] [google] [report]

*ACK accordingly
also notice the fade and (if you can see it in the blown-out video) the gamma correction implemented on the receivers
webm related: the "sender" bluepill has an F072 aboard. so I can use CAN and USB at once. here is a soft-USB-serial session with my CAN monitor, where I send a message to turn on updates for channel 0 at 50 hundredths of a second and receive analog input back. starting around 33s I start turning the pot connected to that input

>> No.1611780

Congrats! only 1 right angle.

>> No.1611789

90 degree traces bad is just a meme

>> No.1611794

They matter in rf

>> No.1611795

Not bad, unnessecary. #2 looks odd compared to all others. No need to change anything.

>> No.1611797
File: 423 KB, 2048x1536, IMG_20190517_114011.jpg [View same] [iqdb] [saucenao] [google] [report]

I'm back from grocery shopping time to will my magnum opus into existence

>> No.1611799

Shit i didn't notice that i will fix it to 45 like the others

>> No.1611808

fix that right-angle trace

>> No.1611809
File: 535 KB, 1020x773, 1558078046975.png [View same] [iqdb] [saucenao] [google] [report]

Something like this

>> No.1611810

Yeah I know I didn't notice it before

>> No.1611812

KiCAD sometimes just does that, you sometimes have to really force it to go one way instead of the other. But the resulting aesthetic PCBs are more than worth it. Mind me asking what those big circular pads are for?

>> No.1611813

Right angles are only a problem if you etch at home or have to deal with microwave frequencies.


>> No.1611814

Of course they don't actually matter in almost all cases. But they make your PCB look worse.

>> No.1611816

Anything with a frequency component (i.e. AC, RF and things that turn on and off) will reflect off the corner. Whether that's a problem if another matter, but at the very least it's bad practice and a bad habit.

If you do end up having these available to buy, remember to see if you can get the service manuals, if the things have any known problems or ""unobtainium"" (often less of a problem than people make out tho), that the CRT is not on its last legs or that there are some tubes available for replacement, and of course to get 2 or 3 so they can eventually cannibalise each other.

>> No.1611819

>But they make your PCB look worse
who cares
also subjective

>> No.1611820

>get 2 or 3 so they can eventually cannibalise each other
mate I barely have enough room in my flat for one of those things, though I would like to try experimenting with turning a scope tube into a vector monitor for a computer (i.e. all the computer graphics are turned into lines traced by the oscope as a really complicated dynamic Lissajous pattern)
I'll remember to ask for the service manuals thanks. But considering their age I can probably get them online. Like the Hitachi VC6145 service manual that shows up first on google:

>> No.1611821

>mate I barely have enough room in my flat for one of those things
Then do what you can.

>> No.1611824

Plastic leg holes

>> No.1611834
File: 20 KB, 1280x1280, gondolacap 2.0.png [View same] [iqdb] [saucenao] [google] [report]

May I present to you:
Gondolacap ceramic edition
suggestions are welcome

>> No.1611839
File: 35 KB, 1280x1280, gondolacap 2.0.png [View same] [iqdb] [saucenao] [google] [report]

With a number:

>> No.1611841
File: 1.02 MB, 2560x1536, 20190517_073845.jpg [View same] [iqdb] [saucenao] [google] [report]

Electric motors are technology... I meant electronics.

Is it possible to rewind a BLDC motor, so I have more torque? I don't need speed that much, to be honest.
I just need to wind more turns, right?

>> No.1611844
File: 135 KB, 1280x1280, gondolacap 2.0.png [View same] [iqdb] [saucenao] [google] [report]

with body shading:

>> No.1611847
File: 134 KB, 1280x1280, gondolacap 2.0.png [View same] [iqdb] [saucenao] [google] [report]

Final version with lead shading and transparent background. Sorry for the image spam.

>> No.1611854

I like it. Make some more gondola parts and it may become a nice image to use for future generals.

>> No.1611857
File: 119 KB, 1080x646, Screenshot_20190517-145446~01.png [View same] [iqdb] [saucenao] [google] [report]

Very basic question here:
I have 16V (or so) AC and need around 3.3V DC. I thought about using a diode bridge to turn AC into DC, like pic related and then a Resistor to drop it to 3.3V.
Three questions:

1. What DC voltage will I have after the diodes? Wasn't there something like a factor of √(2) or something like that?

2. Would some generic 1N4148 diodes work?

3. What resistance would I need to get 3.3V? I thought about using kirchhoffs voltage law, so I would know the voltage that the resistor is supposed to drop is X-3.3V where X is the supply voltage. I can't solve U=RI though because I don't know the current needed. I don't know the current drawn/ the resistance of the ESP8266 I want to power either so I can't calculate it. Any thoughts? Thanks.

>> No.1611862
File: 161 KB, 1229x782, Clipboard01.jpg [View same] [iqdb] [saucenao] [google] [report]

What the fuck flatcam?
These two things aren't even fucking similar.
What sort of garbage gcode is this?

>> No.1611863

>I don't know the current needed

Well that's your first problem. Then once you've got that, use a suitably rated linear regulator.

>> No.1611869

hello, got a question about control theory.
In class I saw that control algorithm are written as recurrence relation in source code but why I never see that on internet ?
Every time I look for PID examples they all use the same technique : an integral with *dt and a differential with /dt
Example : https://github.com/br3ttb/Arduino-PID-Library/blob/master/PID_v1.cpp
Instead of something like :
output = Ki*sample[n-1] + Kd*sample[n] + sample[n-3]
Someone knows ?

>> No.1611870

The DAQ you're using is only 12-bit at a +/-10V input range (20V total). That means that the resolution for your digital data is 4.88mV per bit.
You are getting those spikes because the signal is going between those 4.88mV levels and the ADC can only read is so well. If you had a higher resolution ADC, say 16 bits, those spikes would be much smaller because your voltage per bit becomes only 0.305mV.
Its simply a limitation of your hardware.

As far as programming around them, you can always select a section of data, and if you find a peak, compare its value to the values of the data before and after it. If the data values before and after the peak are the same, and the peak value is 1 bit higher, you'll know its a spike.
X = "peak" data
Compare the values of (X-1) and (X+1) data points, if they are equal, subtract one bit from the X value. If X is now equal to (X-1) and (X+1), its probably just a spike.

>> No.1611872

Its possible, but it would probably be much easier to run the motor through a gearbox, or even just two sprockets and a chain.

>> No.1611873

IF you need regulated 3.3v for a uC, get an actual regulator. Dropping 16 volts to 3.3 with a linear regulator is a bad idea, it will probably dump a lot of heat. Look into a switching regulator.

>> No.1611875

Different Programming styles.
At the end of the day, if it works, it works. Most people don't care about speed or efficiency, just end results.

>> No.1611877
File: 277 KB, 1536x2048, IMG_20190517_155534.jpg [View same] [iqdb] [saucenao] [google] [report]

Ah, much better.

All i have to do now is to tune the line width settings and such and then i will be able to print the artwork on the pcb, draw a silk screen with the same pen, and then swap the pen for a drill and let it also make the holes for tht and such
I could probably let it even draw a soldermask onto it with something other than a sharpie since i don¨t think sharpie can resist solder awfully well

>> No.1611879

You can buy solder mask cheaply from Ali.
It's UV cured, so you'd normally use a transparency but you could experiment with mounting a uv laser on your printer.

>> No.1611902

Shit i can't seem to figure out how to change flatcam from milling to drawing, so instead of milling where copper is not supposed to be it mills (draws) where it IS supposed to be

The problem with solder masking is that it is yet another step for every single pcb i do, so i will maybe just solder it with out the mask and use a transparent resin spray pain for protection from elements

>> No.1611904

It is direct drive hub motor. BLDC or PMSM (I don't know). So, gears and chains are not only less efficient, but also pretty difficult to fabricate, since you would need welder and probably a lathe and I don't have such toys. If I had - I would make entire scooter myself.
Rewind seems to be more reasonable option, which should solve two problems: high resistance of windings, and high KV. It is much easier too, disassemble the wheel, desolder windings (Y arrangement) and wind new windings unsung multiple wires. Since it is low voltage, would have only 10 turns max per thing you wind in, tooth of stator, IDK

>> No.1611970
File: 113 KB, 2048x1152, 4 bit ripple counter.jpg [View same] [iqdb] [saucenao] [google] [report]

>> No.1611975

I want you to know I love you anon, with all my heart.

>> No.1611976

love you too

>> No.1611987

>It's UV cured, so you'd normally use a transparency
Use high quality tracing paper, transparencies never work very well.

>The problem with solder masking is that it is yet another step for every single pcb i do, so i will maybe just solder it with out the mask and use a transparent resin spray pain for protection from elements
The process in >>1611877 is way more involved than masking and etching, honest to god man.

The one you linked to is really very verbose. PID loops are being used more and more now by non-specialists with code/control, so that's likely to be for a biologist or chemist or something so they can be hands on with making the equipment for experiments and what have you. Maybe google is selecting those results over more "technical" (normal) ones because they've become more popular? Also a lot of forum posts are copy pastes, as is a lot of working code unfortunately.

>> No.1612000

>microwave frequencies
that's just about par for the course anymore

7/8 triggering, very good

no you don't. try the / key

saved for next OP

>> No.1612058

> Is it possible to rewind a BLDC motor, so I have more torque? I don't need speed that much, to be honest.
Will the core accept more copper (both in terms of space available and saturation flux)?
> I just need to wind more turns, right?
Right - assuming the core isn't saturating. If it is, then more copper won't help. If you're designing a motor from scratch, you use more poles for higher torque and lower speed.

Flux is proportional to turns and current, so using fewer turns of thicker wire (or more turns of thinner wire) doesn't change anything (double the turns, half the cross-sectional area of the wire => half the current, double the resistance, same flux, same voltage drop from resistance, half the I^2R losses). Although inductance increases with the square of the number of turns, so you need a higher voltage for a given speed in spite of the lower current.

>> No.1612063

why do you hate yourself that much?

>> No.1612065

What does PID look like in pseudocode? I know I could handle it but I haven't tried to yet

>Use high quality tracing paper, transparencies never work very well.
Transparencies work if you use an inkjet printer with pigment ink, tracing paper if you have a cheap laser printer and expose the print to paint thinner vapor

>> No.1612067

i don't, it's fun
you just might not be autistic enough

>> No.1612069

Imagine ending up in the past and you need to build a time machine. You know exactly what the circuitry is supposed to do but there are no microcontrollers yet, only TO92 transistors and other discrete components. By the time you finish you're alreadt 92 years old and the time machine is working, but there's no point in using it because you're already dying of organ failure, and everyone else thinks you're just a nutjob.

Years later someone comes up across your time machine, manages to reverse-engineer it, invents a time machine that looks oddly similar to the one you used to go into the past and tests it, only to become stuck in an era where no time machine was available.

>> No.1612070

16V AC usually means 16V RMS, so multiply by √2 to get the peak = 22.6V. Then subtract 2 diode drops (~0.65V each for silicon, less for Schottky) = 21.3V.

If you plan on dropping that to 3.3V, you need to drop 18V. With a linear regulator, that means wasting 5.5x as much as you're using. And a resistor isn't an option; A 10% change in current draw translates to a 55% change in voltage.

If the AC supply is several amps and you only need a few mA, a linear regulator will suffice. Otherwise you need a switching regulator (buck converter).

>> No.1612073

you got a point there
Can we have a webm of this baby functioning?

>> No.1612076

The theory is written in terms of integrals and derivatives. Originally, PID controllers were analogue devices (first mechanical, then electronic). In DSP, the derivative becomes the difference between samples, the integral is the accumulated sum of samples.

(The derivative may be low-pass filtered to remove noise, which typically means using a weighted sum rather than just x[n]-x[n-1]).

The various terms can be combined into an IIR filter (the integral term can't be implemented in a FIR filter), so y[n]=(weighted sum of x[...n] and y[...n-1]). Integration is just a basic IIR filter: y[n]=y[n-1]+x[n], and the proportional term is just x[n].

Also: practical implementations usually have some mechanism to prevent integrator wind-up (if it takes a while to reach the setpoint, the integral term gets large and the system takes a long time to stabilise), e.g. clamping the integral term to fixed bounds and/or disabling integration while the output is saturated.

>> No.1612081

where "samples" are actually the error, the difference between the set value and the process value

>> No.1612086

Maybe. The derivative term may use the derivative of the process variable rather than the error so that you don't get a spike when changing the setpoint.

Using the derivative of the error is preferred if the setpoint changes continually but slowly. Using the derivative of the process variable is preferred if the setpoint has occasional sudden changes.

>> No.1612088

Wanted to follow up with this. Anon was Right, I replaced the Relays with new ones (Hard to do since those ones were old af and the old pin outs dimensions were so large) and it's working flawlessly. For $40 Cad (30Usd) 20V & 5A is pretty good.

>> No.1612091

how do i into webm
record mp4 and handbrake it?
i'll do it on monday probably, not at home rn

>not travelling back in time and cumming into the primordial ooze

>> No.1612093
File: 128 KB, 1446x1165, 1546647132963.png [View same] [iqdb] [saucenao] [google] [report]

if you do that, the corvids will have become the apex intelligent life form

>> No.1612129

>Will the core accept more copper (both in terms of space available and saturation flux)?
I haven't disassemble the thing yet (since I can't find fucking torx with a hole anywhere), but judging from pics from internet looks like I can add couple turns no problem.
Saturation flux - I don't know. Is there any formula that will allow me to calculate it, knowing geometry (cross section) and material?
Also, I don't know much about transformers and motors, but I wound couple transformers in the past using this formula S=1.2 sqrt(P), where S is section of iron core (cm), and P is power, but I think it is very very approximate thing, which is only valid for 50 Hz 220V mains. Shit worked fine though.
>Flux is proportional to turns and current
Right. Either you increase current (which is problematic, since battery trips at 25A, which is already too much for this motor, which was designed only for 15A), either increase number of turns (which is also pain in the ass, but at least copper is cheaper than batteries and new controller).
>so using fewer turns of thicker wire (or more turns of thinner wire) doesn't change anything (double the turns, half the cross-sectional area of the wire => half the current, double the resistance, same flux, same voltage drop from resistance, half the I^2R losses). Although inductance increases with the square of the number of turns, so you need a higher voltage for a given speed in spite of the lower current.
Yes. I give zero fuck about speed (actually no, but I may trade 5-7 km/h from top speed).

So, what should I read, so I can increase number of turns knowing what I'm doing?
Can I 2-3 solid thick wires instead of 6-8 thin wires?

>> No.1612130

wait a minute
the cheap bench power supplies have both a voltage and current adjustment in pictures

I though current was determined by the resistance and voltage and therefore couldn't be independently adjusted while maintaining constant voltage

>> No.1612133

They maintain constant voltage until the set current limit is hit, then they lower the output voltage.

>> No.1612135

Okay that makes more sense.
If I ever get one of those hopefully it comes with a manual

>> No.1612169


>> No.1612172

I can see that's a Y safety gondola (y tho)
gondola QFN? (yeah no legs)

>> No.1612189

>the / key

it's just a generic ceramic

>> No.1612193

oh I've been to a shitty college.
they ditched the decent analog scopes and replaced them with bottom-shelf digital ones.
This was widely regarded as a bad move, but nobody dared to say that out loud.

>> No.1612201

We've got 4-channel USB digital scopes for half the lab computers but even in 3rd year labs we never used them. Probably because I looked up their price tag and it was something around 10k. We also have some normal 4-channel digital scopes, which are a bit of a pain to use but seem to work just fine. Can't remember their brand name or price however, and there aren't that many so I usually end up using a Hitachi analog scope. All our DMMs are brand name Flukes or Hiokis too.

>> No.1612205

Freshman here. How do I steal equipment from university?
>inb4: Tyrone.

>> No.1612207


>> No.1612220

I know people that stole oscilloscopes, but they won't share the secret.
Do I blow this up, wait for them to trash it, and pick it from trash and repair?

>> No.1612226

I stole an old spectrum analyzer once. I told the lab supervisor it wasn't working, he told me to go throw it in the dumpster. I went and threw it in my car. I didn't expect them to be so apathetic about that but they were.

but really, make friends, make sure the lab people know your name and you'll have first pick of any stuff they're getting rid of.
If you spend a lot of time in the labs, helping keep the place neat and organized will earn you a LOT of brownie points and they can be more easily persuaded to get rid of things you want.

>> No.1612235

>Do I blow this up, wait for them to trash it, and pick it from trash and repair?
It can be incredibly hard to repair an oscilloscope.

>> No.1612240

>tfw likely fried an opamp soldering it to the board

>> No.1612242

>I stole an old spectrum analyzer once. I told the lab supervisor it wasn't working, he told me to go throw it in the dumpster. I went and threw it in my car. I didn't expect them to be so apathetic about that but they were.
>but really, make friends, make sure the lab people know your name and you'll have first pick of any stuff they're getting rid of.
>If you spend a lot of time in the labs, helping keep the place neat and organized will earn you a LOT of brownie points and they can be more easily persuaded to get rid of things you want.
Well, I need to survive until labs first...
But yeah, common sense. I got couple school PCs and printers like that.
I know, so it would be pretty difficult.

Okay, but what about electronic components? Is it ethical to put them into pocket and stuff?

>> No.1612244

>I need to survive until labs first...
if you want to do a project, do one. When I was a freshman I rebuilt an amplifier, asked around and they let me have lab access to do that project.
If you want to make connections, doing a DIY project as a younger student is a great way to do that. If your school has a shred of decency, your EE professors will wildly approve of electronics hobbyists who want to learn.
If you do that you'll hardly even have to steal, you can get a lot just by asking.

>> No.1612264

Also my RGB LED strip I've been using for lighting keeps changing color when I'm not touching the remote, and it happens when there's no battery in the remote either. It's a radio remote instead of an IR remote, so I imagine some other RF remote or device is accidentally sending my lights signals. I tried covering the inline receiver with alfoil but it isn't working. Just tried grounding the foil now, but my remote's signal still gets through.

>he doesn't use IC sockets

>> No.1612270

>It's a radio remote
that was your first mistake

>> No.1612273

Not like ali had an option for it on that listing. I never intended on using it for lighting this often either, otherwise I wouldn't have gotten something with such poor colour rendition. Ideally I'd have a 6000K and a 2000K LED COB both running off constant current supplies that I can change the current of individually. Maybe a red COB too just for that edgy factor, especially as a ring light around the other COBs so everything gets a red outline in their shadow.

>> No.1612358

Is it ethical? No. Did it stop me from pocketing a bunch of JFETs during one of my labs because JFETs are stupid expensive? No.

>> No.1612390

Is it possible to get neon tubes for cheap? Custom designs I'm assuming would be expensive but what about a couple of straight segments or just simple shapes? No signs. Just some basic neon lighting.

ACTUAL NEON PLEASE. Not that fake neon shit with an LED strip and a diffuser. Not EL wire. Not cold cathode lamps. Proper Neon tubes (or argon, xenon, etc. you get my point).

>> No.1612464

Well for starters they're not exactly bendable, so for most applications they're useless because people tend to buy neon tubes for the purpose of having custom shapes as made by the manufacturer to order.
Secondly, they're not exactly durable, so even if you found some unwanted ex-soviet stock in Ukraine you'd need to pay out your arse to get them shipped.
Thirdly, they're a pain to drive, meaning the market for them has dropped as LEDs and other much simpler lighting methods have turned up. That doesn't mean there isn't any market for it, but it does imply that it will be a fairly niche market that only hipster club managers enter, so I'd not be too hopeful about getting anything affordable. I'd check out your local junk shop to see if they have anything that suits your requirements. Small gas tubes (H, He, Ne, Ar, Hg, etc.) are still made for science demonstrations and may come with their own driving circuits, and could be tolerably priced from the right supplier, but they won't exactly be good for lighting.

Another thought is going for a (laser) flash lamp tube, which might be possible to drive continuously with some sort of constant-current driver.

>> No.1612496
File: 282 KB, 1536x2048, IMG_20190518_130312.jpg [View same] [iqdb] [saucenao] [google] [report]

I did it!
It's fucking beautiful.
No hand melting with acetone
No sharpie fixing of crappy laser tonner transfer
No ironing, no nothing.
Perfect coverage ready for etching.
I can even just swap the sharpie for a white one and add a fancy silk screen if i wanted to, but fuck that

>> No.1612497

Nope. The only reason anyone uses neon (and similar) is that it's relatively straightforward to make shapes to order. If you don't need that feature, it's expensive, fragile, unreliable, and dangerous, which is why no-one bothers making off-the-shelf neon tubes.

>> No.1612500

looks pretty crappy desu
proper photoresist or toner transfer would have produced a much better result

>> No.1612503

Sour grapes eh?
There are no flaws in the traces at all, if i etch this the pcb will perform flawlessly.
If i wanted even better results I could use even thinner pen and perform poly bed leveling on the pcb with the probe, but this turned out so well I don't need to do any of that stuff.
This is so much faster and more convenient than the shitty toner transfer methods i tried before (both hot and cold ones) that this is not even a competition.

>> No.1612512

>There are no flaws in the traces at all, if i etch this the pcb will perform flawlessly.
maybe it's the poor photo but every corner looks fucked to me

its good enough here because it's all big traces but for small SMD stuff (which is where you really want etched PCBs - your pcb could be done on a veroboard in 5 minutes) it's not gonna be good enough

>This is so much faster and more convenient than the shitty toner transfer methods i tried before (both hot and cold ones)
should have used photoresist instead - toner transfer takes more fucking around at first - but is very quick once you developed a good process
some people even modified their laser printers to print on a pcb directly

>> No.1612521

Photoresist is pricey, since you need the transprent foils to print on, then to develop it and whatnot, plus the photoresist pcbs cost a bundle compared to regular ones.

I would go for such solutions if i needed such fine detail, but none of my circuits will be so small where i wouldn't be able to use my super simple process of
>printer paints artwork
>printer optionally drills tht holes
>toss into fecl3


>> No.1612522

why not mill directly then?
etching is pointless if you don't need the detail

>> No.1612523

>why not mill directly then
there are several reasons why drawing and etching the board is better for me rather than milling it.
I don't really want to write an essay on all the reasons here, but if you want to know you can watch some pcb milling tutorials on youtube

>> No.1612532

>right in the middle of the blank PCB
Great work but that's a little wasteful.

>> No.1612537

We live in times of plenty, enjoy it

>> No.1612540

I have noticed that literally all EE students have sticky hands. Why?

>> No.1612547

lol that's nice

>> No.1612551

>Photoresist is pricey, since you need the transprent foils to print on, then to develop it and whatnot, plus the photoresist pcbs cost a bundle compared to regular ones.
None of this is correct. Transparencies are pretty cheap and reusable and as mentioned above you can use tracing paper. The boards with photoresist already applied are not much more expensive than boards without and you can buy the damn paint and apply it yourself anyway. Even the UV boxes are not expensive. Etching the boards can be fairly expensive though.

>> No.1612557

>Etching the boards can be fairly expensive though.
FeCl3 is cheap

>> No.1612567

a true cuck only uses cucl to save the environment

>> No.1612569

Can be made cheaply with HCl

>> No.1612574

I make up my own Edinburgh etch solution, and it's the other equipment that's expensive. I have my own sooper sekrit methods for the etching bath that's cheap and really good but not volume friendly, but standard equipment like a bubble etch bath costs, at least relative to everything else besides maybe the printer. Yeah you can use a tray or whatever but not always.

>> No.1612576

And copper chloride is super useful in making high precision boards, though I'm not totally happy with my process thus far.

>> No.1612584
File: 278 KB, 1536x2048, IMG_20190518_173611.jpg [View same] [iqdb] [saucenao] [google] [report]

Final version.
I am going to try to test etch it now, wish me luck.
The infill has a bit of a pattern, i hope i is covered enough. Otherwise i will have to do larger overlap.

But holy shit, watching that sharpie moving around drawing the schema bit by bit is incredibly satisfying.

>> No.1612586

Has anyone ever tried to just print directly on the PCB with an acid-resistant plastic like PETG?

>> No.1612594

I considered it but the detail is not good enough
Sharpie is no harder than normal printing and the result is much better
plus with a plastic layer it would be superhard to sponge etch

>> No.1612596

0.1 nozzle would beat a sharpie easily

>> No.1612598

but i am not going to change nozzles every time i want to make a pcb

>> No.1612599
File: 522 KB, 1536x2048, IMG_20190518_180406.jpg [View same] [iqdb] [saucenao] [google] [report]

okay, first attempt turned out to be MEH
i think i rubbed too hard with the sponge and i managed to wipe off some of the sharpie
the infill pattern left some holes too as i assumed,
i have to increase the overlap between sharpie lines

>> No.1612607

Welp, i tried to beep it and all contacts work flawlessly, so thats nice.
I'll try to solder it to see how well i can do it without a mask.

>> No.1612610

>you need the transprent foils to print on
but you don't. you just need a blue laser pointer with a respectably small aperture so you can swap out your current sharpie with it
>to develop it
1% washing soda soln, straight from the supermarket. it's $6 for a 2kg box here

then don't, just let your G-code work its serpentine path over your ground fill

>> No.1612695

seems like the only major where the tools to create are semi-cheap but simultaneously not marketed towards individuals and can be ridiculously expensive or over-priced.
>an EE student with sticky hands for an altera FPGA, there was a cabinet filled with 50-100 oops

>> No.1612720

You can get cheap FPGAs

>> No.1612730

Batteries are electronics.
I found a lead paperweight, 6V 12 AH.
How can I recover it?

>> No.1612784

yeah I wasn't justifying my own theft for that reason. Though the 'cyclone' has a shitton of nice peripherals that wont come cheap

but i meant to mention also that EE as a profession and hobby goes hand in hand, so seems like wanting to own the items would explain stealing

>> No.1612788

glad to see you read /ohm/ RULE 0
keep going and read /ohm/ RULE 1

>> No.1612839
File: 541 KB, 567x654, 1547150838561.png [View same] [iqdb] [saucenao] [google] [report]

>Optocoupler : digital signal like PWM pulse
>Isolation amplifier : analog signal such as sinusoidal
Did I get it right??

>> No.1612840

Oh, I found.
>>I have junk, what do?
>Take it to the recycler.

>> No.1612847

but did you even google


>> No.1612849
File: 29 KB, 600x325, fet_optocoupler_potmeter_100.jpg [View same] [iqdb] [saucenao] [google] [report]


nope. you can use optocouplers to send analog signals. use a DC voltage to bias the LED on, then AC couple your signal on top of that. a vintage gadget called a vactrol was often used for this purpose.

>> No.1612857

I googled. People say that I should try adding water there. Idk, it doesn't take charge. Even with water.
WHat is really cool, is that it had a fucking negative pressure inside.

>> No.1612862
File: 53 KB, 1088x624, Noise-Hardened-Linear-DC-Signal-Opto-Isolator-Schematic.jpg [View same] [iqdb] [saucenao] [google] [report]

normal opto coupler works too

>> No.1612877

Wasn't a vactrol made with an LDR?

>> No.1612888


true but irrelevant. wikipedia's article explains the vactrol in more detail than anyone could possibly need, with 87 footnotes in case you want more.

>> No.1612911
File: 249 KB, 1080x856, succ.jpg [View same] [iqdb] [saucenao] [google] [report]

Newfag here, Is it possible to replace the batteries in pic related? I know they don't sell official replacements, but couldn't you replace it with a generic battery of similar voltage?

>> No.1612925

>but couldn't you replace it with a generic battery of similar voltage
Certainly. They probably use a dozen 18650 cells of some specification or another. Take it apart and see what you're working with. Ideally there would be lettering on each cell that would direct you to a datasheet of some kind.

>> No.1612999

There might be a third party one available, but if there isn't, you can score the seams on the battery with a hobby knife, and then see if there are 18650 cells. You could then probably replace them no problem, since I doubt that they'd bother putting in a circuit that can tell if the cells have been replaced.

>> No.1613027
File: 34 KB, 456x429, 1556669357917.jpg [View same] [iqdb] [saucenao] [google] [report]

My sensor circuit has 3.2V output ,but it's 26Vp-p floating above PE in AC domain
Should I connect it to GPIO of MCU???

>> No.1613038

Just give them both a common -ve reference first, chances are it's just floating up thanks to mains capacitively coupling to some part of your circuit. An open-collector of a FET could also potentially float up that high if they are already tied together, so an external pullup could help keep things constrained within your rails.
Just slapping them together without this shouldn't have any adverse effects, but I'd say it's good practice to connect them all to a common -ve rail before proceeding.
And what the fuck is PE supposed to mean

>> No.1613044

>but I'd say it's good practice to connect them all to a common -ve rail before proceeding.
What about floating my MCU with power bank?
>what the fuck is PE supposed to mean
Protective Earth

>> No.1613050

>What about floating my MCU with power bank?
Just connect the 0V rail of your sensor circuit to the 0V rail of your MCU to the 0V rail of your power bank. Then measure between the sensor/Vcc pins on either device.

>> No.1613091

What is -ve supposed to mean? Is there also a +ve?

>> No.1613099

-ve = negative
+ve = positive

>> No.1613104

What is the best way to switch between two powersources? I have one that is always 3v and one that is 3-5v i want to use the 3-5 but only if it is below 3.5v otherwise use the 3v.
Is two mosfets superglued together the best solution? Currents 0.5a tops

>> No.1613109

Nevermind. Some chucklefuck left one of the channels on the oscilloscope to 100X and I being a bigger chucklefuck didn't bother to check. Good thing I went and double checked with a multimiter before trying to desolder the whole IC.

>> No.1613111

Both relative to a common 0V aka GND, so a dual supply?

>> No.1613113

Well when I said -ve I was referring to the 0V rail, because I assumed you weren't using a dual supply.

>> No.1613134

>watch someone on youtube solder smds
>he puts solder on his iron tip
>gently touches the smd
>perfect amount of solder flows to the smds, the smd centers itself and is flawlessly soldered to place

>take the iron and put a bit of solder on tip
>touch the smd
>solder covers every single pad and trace as far as eye can see without even an of it ending up on the smd

fucking assholes, they never mention they used CGI in those tutorials and soldering smds in real life is impossible

>> No.1613136

>he puts solder on his iron tip
never do that unless you pre-tinned the pads or use extra flux

>> No.1613139

>solder on his iron tip
>use extra flux
This is entirely how I solder anything, SMT or THT.

>> No.1613141

what flux do you use?
i asked in electronics stores here for the flux gel thing and none of them sell them and on the internet i see them at outrageous prices with like 10 milliliters going for $20

>> No.1613145

Rosin flux paste in a tub. Bought it for probably more than I should have at jaycar, but it's lasted my years so I can't complain.

>> No.1613146
File: 72 KB, 1001x1001, s-l1600[1].jpg [View same] [iqdb] [saucenao] [google] [report]

Can is it gelatinous enough where i can apply it with a syringe?
Also does it have an expiration date? i don't want it to turn into a rock after a year

>> No.1613157
File: 46 KB, 810x464, Thierrymin_v3_schem.jpg [View same] [iqdb] [saucenao] [google] [report]

Total beginner here hoping to build a theremin. I read through Mims' Getting Started With Electronics in the OP but still don't really understand how to read a circuit diagram like pic related (schematic for a theremin). I'm wondering if one of the other books in the OP would be better for me to read through and maybe if someone could just give me a quick rundown on what I'm going to need/how to get started.

>> No.1613160

No expiration date as far as I know. The stuff I have is transparent, probably just rosin in some sort of solvent to make it semi-liquid at room temperature, and it's really easy to apply. A bit too thick to use a syringe with, but a popsicle stick would spread it wonderfully with little force. The stuff in your picture looks harder and and opaque and it may not be rosin, since the "No ..." at the bottom might say no-clean. Getting no-clean flux might be the way to go, since after slathering your board in rosin you have to slather it in IPA to get rid of it again, but from what I've experienced from those no-clean flux pens, the flux isn't nearly as effective. A concentrated flux paste might be different to whatever is in that pen's solution however.

>> No.1613170

Well the smds i am using are no smaller than sot23 so i can spread it with a stick
didn't know fluxes were clean and noclean, i will definitely buy a noclean then since i'm lazy, does the more watery one have some special designation?

>> No.1613172

>does the more watery one have some special designation?

>> No.1613176
File: 32 KB, 350x318, kalafuna30b[1].jpg [View same] [iqdb] [saucenao] [google] [report]

Well the store i use has pretty much only this, it is pure rosin and pretty cheap too, only two bucks so i am going to try it
i don't have a heat gun, so i hope i can just smear it on and stick my iron into it

>> No.1613178

You can dissolve it in alcohol

>> No.1613185

>pure rosin
Won't that be solid? Not like you can't dissolve it in white spirits or something and make up your own paste, which is probably something I should attempt. Actually my pine deck has a bunch of resin leaking out of the handrail, and slicing off some of this I found I could get it to work as a flux without issue.

>> No.1613190

Should be pretty easy. I will just toss some into a wider syringe, with some ethanol and make my own flux paste
if it doesn't work it's so cheap it doesn't matter

>> No.1613191
File: 328 KB, 2155x803, schematic.png [View same] [iqdb] [saucenao] [google] [report]

Building this guitar effect and trying to understand it. Some versions of the schematic omit the 10k R14 resistor as pictured here. Any clue as to what it's for?

>> No.1613192

10k are usually pulls downs or pull ups

>> No.1613201

R14 modifies the (low) cut-off frequency of the high pass filter formed by C13 and whatever comes east of it. You may not notice the effect at all.

>> No.1613203

It should be explained in the book, don't expect a shortcut. Did you get the principle behind the Theremin organ, the two oscillators and the mixer?

>> No.1613247
File: 100 KB, 496x1500, 81xXizPh-6L._SL1500_.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1613257

0V of my sensor also float too

>> No.1613258

are there any dip photointerrupters that work with 5v microcontrollers without requiring an analog pin to read their values or associated comparator circuits?

>> No.1613259

ordered some nice stm32s and IRs (along with the tc100 miniware iron)

Gonna do some lap + sector timing counts for mini4wd tracks (or anything really, it is generic).

>> No.1613262

get his

>> No.1613264

that costs almost as much as a new ts100

>> No.1613266


>> No.1613269

and that's a good thing, it's a pure american made product

the best flux you will ever use, it is usually only sold in bulk to companies but was made special thanks to rossmann

>> No.1613274

Made me laugh out loud - I prefer this version without the number

>> No.1613280

With the amount of soldering i do, i just cannot justify such a massive purchase when i can make similar goo myself by dissolving rosin in ethanol and get the same amount of goo for like 50 cents

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