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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

>> No.1613282

Showing 1-8 of 50 reviews...

>> No.1613313
File: 1.18 MB, 2560x1440, batteries.jpg [View same] [iqdb] [saucenao] [google] [report]

Ok, just took the vaccuum apart and fond out that these are nickel-cadmium, not lithium.
Anything I should know about these?

>> No.1613330

You can use a digital pin. If you want some more robustness, and an is buffer / not gate with hysteresis.

NiCads are absolute horseshit. It'd be easier to buy a battery and charger, and wire yourself a holster to make the battery go in.

NiCads barely last a year or two, I'm lmao'ing that even fucking Dyson uses NiCads. I think NiMH might be compatible with NiCad charging circuits (current based that trickles off above about 1.2 * pack voltage)

Also, never smell an exploded NiCad pack. Enjoy ur heavy metal poisoning.

>> No.1613337

nvm, your vacuum wasn't Dyson. I was looking at the glowy purple bits, I'm surprised they were able to get out of a trademark infringement because Dyson is characteristically a translucent purple and soft gray.

>> No.1613349

>if it is below
a slightly unusual application, but ok
a comparator or two + a pair of p-ch MOSFETs ought to do it. choose comparator for low power and push-pull outputs, choose MOSFETs for low Rds(on) and low Vgs(th), the AO3401 would be great if you don't mind a SOT-23

why would you be using an analog pin instead of a digital pin with Schmitt trigger?

>NiCads barely last a year or two
really now? I have a beard trimmer which has lasted almost 20 years and hasn't experienced a significant reduction in capacity to notice. still original pack. you just have to maintain them, with the full-drain and recharge cycle

>> No.1613379


it's an optional safety device. the 10K makes sure there's little or no DC voltage going to the pot. in this way, if the pot is temporarily disconnected by vibration, or whatever, you wont get a loud DC pop that could blow a speaker.

>> No.1613396
File: 45 KB, 555x376, wtfisthat.jpg [View same] [iqdb] [saucenao] [google] [report]

Can anyone here translate this meme to me, because I don't get it.

>> No.1613401


top: sophisticated soviet engineering to extract truth from dissidents.

bottom: simplistic american pig dog engineering to extract truth from sand-niggers.

>> No.1613402

daily reminder that the commonly-seen NC-559 and RMA-223 fluxes are designed for leaded alloys only. this one otoh is universal https://amtechdirect.com/product/amtech-vs-213-a-tf-tacky-solder-flux/

>The original scheme of the device "electric"
>Circuit modified by our reader

>> No.1613405

>The original scheme of the device "electric"
Wtf is "electic". Seems incomplete.

>> No.1613411

you're absolutely right. it's "electrosleep" kek

>> No.1613416

Kek. Second one is better, it provides better sleeping action.

>> No.1613420

too good for most people, who should start with the original and work their way up

>> No.1613492
File: 2.29 MB, 1280x720, output2.webm [View same] [iqdb] [saucenao] [google] [report]


>> No.1613516


>> No.1613589

>and that's a good thing, it's a pure american made product
Fuck off with that nonsense. Where can I get the Chinese version for 1/10th the price?

>> No.1613604 [DELETED] 

neat. hey maybe if your not busy later i'll suck your dick?

>> No.1613654
File: 121 KB, 1280x1280, gondolacap 2.0 numless.png [View same] [iqdb] [saucenao] [google] [report]

float with respect to what?

here's a shaded version for you

uh, didn't your photo say "lithium" on it

>> No.1613671

>leaded alloys only
Wow what the fuck, no wonder my flux pen wasn't doing the business. I guess I'll stick to rosin for now.
Anyone know about that tube of flux that Louis Rossman uses, and if that's suitable for Pb-free or not? He uses it to repair motherboards so I'm assuming he's also using Pb-free solder paste, but I can't find Pb-free solder paste on ali at all so perhaps he just repairs people's computers with 60/40.

>> No.1613672

If you drew that gondola cap I fucking love you

>> No.1613675
File: 29 KB, 1000x1800, gondolacap.png [View same] [iqdb] [saucenao] [google] [report]

I drew this one a while back too

>> No.1613676

This is why I'm stuck here forever

>> No.1613687

My flux of choice is plumbing flux, since I deal with third grade corroded salvaged shit all the time.
Water and alcohol soluble. But for BGA I would use no-clean shit.

>> No.1613732

It turns out I had a different, but very similar vaccuum compared to the one in the original pic I posted.

>> No.1613736

personally, when I am in a restaurant, when I remember, I just grab a wooden toothpick at the cashier station, and dab paste flux with that. also good for holding mid-sized SMT components in place while soldering

so many variables, but one might be the wrong size of solder wire. the smaller the wire, the smaller the droplet you can put on a tip

the ones on Louis's site are all leaded
>perhaps he just repairs people's computers with 60/40.
yes. he doesn't have to prove anything to anyone much less file paperwork over it. SAC305 and 60/40 can be mixed without any detriment to the quality of the joint

>> No.1613737
File: 279 KB, 1600x1200, 1532269623984.jpg [View same] [iqdb] [saucenao] [google] [report]

I've got an old icom transceiver, like 30 years old. I was talking on it, and smoke started coming out of the PA section. Now it only puts out like 2 watts of output power instead of 100. How do I troubleshoot something like this? Nothing is obviously burned looking on the PA board.

>> No.1613740

>the ones on Louis's site are all leaded
Then what do they use for hand soldering in industry? I assume all their reflowing flux comes inside the solder paste itself.

Smoke sounds like it came from a transformer or inductor, (balun?) check those first. Could be a power resistor also. Assuming there aren't any visible shitstains on the board or on components of course. Checking the state of your electrolytics is also a good practice, since arguably dead electrolytics could have been the cause of some other part letting out smoke.

>> No.1613753

>Then what do they use for hand soldering in industry
lead-free solders, as regulations require, with a flux designed for lead-free soldering. plenty of options in the market

>> No.1613757

why does C22 look so hit up?
assuming you have tested all the transistors and verified none of them have blown short, when in doubt:
acquire or draw a schematic
apply dummy load, key
follow signal through circuit with probe, plot voltages on schematic
find the part that isn't producing an output consistent with its inputs

>> No.1613758

Is that true, that all lead-free fluxes are acidic and needs to be washed off?

>> No.1613759

not at all, there are all kinds of no-clean fluxes for lead free solder

>> No.1613763

What are some good electronic chain stores that sell electronic components? All i know of is radioshack i think and the one in my town closed down years ago. Just wanting to do some little projects in my spare time but have no idea where to get any parts other than online

>> No.1613776

yes but what do they sell these as on ali

>> No.1613783

if you live in a medium-sized US city, you may have a brick and mortar independent components retailer where you can do so, but those seem to be fading away as well. a major chain computer store may have a components section (Fry's used to, might still) or at least a maker section (Micro Center). with Digi-Key having all sorts of shipping options from First Class Mail® on up, no small order service charge, and no minimum order, it doesn't make a whole lot of sense to go to some local shop and end up paying $1.49 for a 555
I can definitely vouch for the practice of buying a reasonable variety of electronics stocks on alibay as specifically suits your interest, so that you have a reasonably good chance of having components to hand that will work for your application

I don't... know. for a first attempt I'd search for lead-free flux and ignore any ad that mentions 223 or 559 because they're likely fakes. then ignore the leaded fluxes and pastes that ali helpfully put into my results, and after a few pages find ten or twelve ads worth a second look

>> No.1613788

Is rosin dissolved in ethanol noclean?

>> No.1613790

Yes and no

>> No.1613797

Searching for "lead free" just comes up with leaded, at least as far as solder paste goes.
Looking for flux paste in particular I'm seeing a bunch of 559 syringes/tubes, but that's a smaller volume than I'd want anyhow. But I am finding some Sn-Bi solder paste, which I didn't expect ali to have. I wonder what that's like to solder with.

>> No.1613802

Ok so I tried some of the M0.9*2.5 PCB rivets and they worked ok, but I did run into a few issues.
Firstly, they were a pain to rivet properly, frequently my punch would wander off to one side slightly and flatten the rivet asymmetrically. Perhaps 1/2 of the riveting attempts worked properly. From what I've seen online this can be amended with the proper riveting tool, which has a solid core to keep the inner rivet open, but I've yet to find one of these on ali. In any case, the punches I was using (an automatic centre punch and a normal hammer punch) had a pretty broad tip, where I think a much narrower tip (~60° to the normal) would help instead. I think the slow increasing pressure from the auto-punch didn't exactly help when it came to the rivet slipping sideways.
Secondly, they say 0.9mm but I had to use my 1.0mm carbide drill instead since the rivets did not fit in the 0.9mm holes. Possibly the rivets are to spec and the fibres in the FR-4 were just pushing outwards into the hole, I don't know. Anyhow I ended up snapping the carbide drill so RIP that testing.
Thirdly, for the gauge of 2-sided copperclad I was using, the rivets appeared to be a bit too short, so I'll likely buy the M0.9*3 ones next. I tried punching the copper itself in a little to make room for either end of the rivet and see if I can get a reasonable amount of the end flattened on the other side, but since at this point I was using the 1.1mm carbide drill, the results weren't stellar and the things still kept going off to one side.

So I'll want to track down some better punches (getting anything other than an auto-punch from ali is tough), buy some new drill bits, and buy those longer rivets.

>> No.1613805

so yes then? good
it makes sense since rosin shouldn't be corosive when it's cooled down
i just want something i can ejaculate over the contacts, solder it and then just leave it there

>> No.1613807

why don't you want lead solder?
It's the best, it beats lead free solder in every single aspect except enviromental crap.
I have a sn-pb solder with a flux core and it solders amazingly even on corroded stuff

>> No.1613811

Because I don't find lead-free hard to solder with at all, I barely notice a difference between it and 60/40. I use it because I thought there wouldn't really be a downside, especially if they stop making 60/40 and other leaded alloys. Of course the price is higher, but being able to hold a part in my mouth or not having to wash my hands after handling stuff is just worth that in my opinion. I've seen the infographics on lead having an impact on IQ and I guess they had an impact on me.
But all I've seen is a surprising amount of equipment for leaded soldering, so much so that I'm starting to suspect that cheap electronics don't use the RoHS stuff. The fact that normal no-clean flux doesn't work well for lead-free took me completely by surprise.

>> No.1613814

unless you live in ancient rome, just holding the solder with a small amount of lead in it in your arm won't do anything noticeable
..you.. don't eat it, do you?

>> No.1613816

Who needs a third hand when you have a mouth?
Anyhow I mainly moved to lead-free because I expected to have more options as to the accessories I used, not less.

>> No.1613817

industry hates the lead free solder, corps only use it because government forces them
even big pcb making houses still struggle with lead free solder during manufacturing

a hobbyist should never touch that shit

>> No.1613818

I might swap back then. I still have a reel of the leaded stuff somewhere.

>> No.1613827

>beats lead free solder..
Of course. The Grey Tin problem of lead-free soldering persists and the mil/med/sci sector is still exempt from the RoHS directive which only addresses industrial mass production, not the small scale use of 60/40. The introduction of lead-free Green Meme soldering products for the hobby market was a successful marketing psyop that created the Cult of Flux we see here in action.

>> No.1613843

I've certainly heard of tin pest, but I doubt I'll ever see it on any PCB I make or buy. It's just too rare, unless your PCB is routinely subjected to particularly cold temperatures.

>> No.1613854

>a slightly unusual application, but ok
well i need to power a device that takes 3.3V (to about 3.7) only but the source voltage can be 3 - 5V, i of course have ldo regulator to handle 4V and above, but the spec sheet says than it needs about the 3.9v to work correctly, so once the supply drops below 3.9V i need to bypass the regulator and feed the device directly
it's the best solution i came up with since they don't make any ldos that have like 200mv dropout, can supply up to .5A and aren't some incredibly exotic shitty tiny smd thing

>> No.1613876

Reminder medical and aerospace equipment only use 60/40 solders. Leadfree simply doesn’t work as well

>> No.1613878

Thanks, but that doesn't make it much clearer. So it can be a pull down, part of a high pass filter, and also modify the taper of the volume pot?

>> No.1613881

If I have a linear regulator that claims a output current of 1.5A min, 2.2 may and I only need μA, as long as the Voltage is as intended for a IC, will I fry my circuit?

>> No.1613896

resistors can be used for many things.

>> No.1613921

and sometimes they can be omitted.

>> No.1613926

Ok the only proper punch tools I can find on ebay are like $70 for a pack of 5 from a name-brand, and these are the ones that videos/tutorials of hobbyists use, so it seems there aren't any chink-made versions. But I figure I can use a bolt with the right size shaft as a punch that will keep the hole open, or even cheaper, a piece of thick acrylic with a hole in the middle sized to fit a nice thick diode lead. So I'll make that thing in the laser cutter tomorrow and see what kind of result I get.

It's the middle one, since it's in parallel with the volume pot I don't think it affects its linearity at all. But the volume pot already makes a high-pass filter, so I assume it just makes the cutoff frequency slightly higher. It's not like the potentiometer's resistance will be much over 10k anyhow. It's definitely not a pulldown unless you count a parallel resistor of a filter to be an "analog pulldown".

>> No.1613934

Volume pot is 100K

>> No.1613935

Well in that case it's fairly significant I guess. What's the capacitance of the electrolytic C13?

>> No.1613951

Patrician. Shit is cheap (ZnCl2 stuff), solders good, and 50/50 solder is good too, less fragile, than 60/40 or 63/37.

>> No.1613954

Two versions: C13=10µ R14=10K and C13=1µ R14 omitted. This is what the first reply hinted at.

>> No.1613956

What's the purpose of D2 and D3 in this circuit?

>> No.1613968

Do you clean the shit up thoroughly afterwards?
That stuff will eat through the copper traces.

>> No.1613972

Yes, since it is conductive.

>> No.1613976

signal clipping, fuzz

>> No.1613978


Thanks bros, buying an oscilliscope on ebay today, have a schematic, and will go through bit by bit.

>> No.1613987

Can I make a breathing LED light with discrete parts or do I need a microcontroller?

>> No.1613997

Don't need a MCU

>> No.1614030


without a micro you'll probably get a linear up-down fade which looks completely different from breathing. with a micro, you can shape the effect precisely using a table of brightness values. and you can use multiple tables for panting, sleeping, yogi-ish, dog-ish, hyperventilation, ataxic, dying, adolescent heavy-breathing prank call, etc.

>> No.1614032


without a micro you'll probably get a linear up-down fade which looks completely different from breathing. with a micro, you can shape the effect precisely using a table of brightness values. and you can use multiple tables for panting, sleeping, yogi-ish, dog-ish, hyperventilation, ataxic, dying, orgasming, adolescent heavy-breathing prank call, etc.

>> No.1614033

how much did you want?

it's the activators that might be corrosive. if you were to throw a touch of hydrohalide acid into it you would want to wash afterward
also, plain rosin flux residue might be sticky to the touch and attract dust etc.

shouldn't have been a surprise, since lead is in column IVb of the periodic table and silver is in some odd-numbered column of tranny metals. their oxides would react to potential flux materials rather differently

>cult of flux
500 joule kek

how about a buck-boost converter? I think you can use the MC34063 to make one of those but I haven't finished my coffee yet

that's a max output current of 1.5A min before it does max output current things like folding back
if there is a minimum output current, it will be stated in the datasheet and is probably on the order of mA

sheeit, a voltmeter would have been enough to get started

weird flux but ok

>> No.1614062

Thanks for the reply. So if I adjust the voltage correctly for the esp8266 and hook it up to the AC/DC regulator, I won't fry it?

>> No.1614069
File: 15 KB, 355x355, violin-rosin.jpg [View same] [iqdb] [saucenao] [google] [report]

https://yarchive.net/metal/soldering_flux.html -- about acid, read the whole text
Short excerpt for the fluxophiles:
"If you need some extra rosin flux, go to a music store and buy a block of rosin like those used by violin players. Ask for the oldest, dried-out block which should make the store owner happy (the musicians prefer the soft, sticky ones). Dissolve as much of this as you can in a small glass bottle containing acetone. Remember acetone is VERY flammable. But it evaporates quickly leaving the rosin behind, ready for soldering. One block will normally last a lifetime."

>> No.1614076

Thing is, rosin in those places is expensive, even stuff they will throw away (hint).
Where can I buy rosin cheap? When I lived in soviet shithole, it was literally sold in auchan. And where can I find borax?
Also I miss ЛTИ-120 flux. Westerners are stupid to make flux this good.

>> No.1614086
File: 222 KB, 914x1200, 1540472789809.jpg [View same] [iqdb] [saucenao] [google] [report]

My open-drain output PWM has huge DC offset
What cause this?

>> No.1614090

Even Amazon has cheap rosin.
And there's Ali/ebay that will ship to any shit hole.

>> No.1614108

Won't customs think this is a weed of sort?

>> No.1614111

How do you mistake solid rosin flux for a weed?
It's unlikely customs will even open the package. There's way too many packages to check.

>> No.1614116

>How do you mistake solid rosin flux for a weed?
Organic subtance. Meth, idk.
I honestly need rosin only for aroma, shit produces nice fumes, effective against houseflies and effective from getting older than 60 y.o.

>> No.1614124

Difficult to get good acetone in a lot of places now, too many surfactants/additives.

>> No.1614132

You can use ethanol.
I takes a while to dissolve in it (a whole block needs a few days) but it works.

>> No.1614133

>anon deleted post to add orgasming
this is why I'm here forever

you might find it stocked by the laundry additives or home cleaning products. may also have it at welding supply or pottery supply

correct. looks like some rando on hackaday said that the 34063 will work* in damn near any topology, including SEPIC. but if you're interested in efficiency, which you might be if supplying from a battery, shitty tiny SMD is where the action is. all about SEPIC here
*inefficiently and slowly but will deliver

show schematic of OD output and whatever is connected to it

>> No.1614134

I ask because I need to fit the circuit in a 4x4x2 cm box and I don't know how much I can stuff in there besides a 555 timer and a few passive components.

>> No.1614138
File: 18 KB, 359x410, Annotation 2019-05-21 024937.jpg [View same] [iqdb] [saucenao] [google] [report]

>100 ohm pull-up
I need current to drive optocoupler
50Hz PWM
50% duty cycle

>> No.1614141

>Also I miss ЛTИ-120 flux. Westerners are stupid to make flux this good.
>Pine rosin 25%, ethyl alcohol, triethanolamine 1-2%, diethylamine hydrochloride 3-5%
Dont use that shit. It's corrosive, hygroscopic and hard to clean. It is good only for large dirty copper wires.

>> No.1614142
File: 42 KB, 800x480, DS1Z_QuickPrint1.png [View same] [iqdb] [saucenao] [google] [report]

Vmax Vmin

>> No.1614150

>>1614134 Arduino Pro Micro is only 33x18mm

>> No.1614151
File: 7 KB, 845x102, 1529999103650.png [View same] [iqdb] [saucenao] [google] [report]

perhaps your comparator isn't happy trying to sink 30mA?
>ultra low power low voltage comparator
>pic related
yup, you need a stronger driver. maybe an 'LVC1G14 or '1G17?

>> No.1614152

Fucking junkies. In my shithole they had banned ethanol.
This made me anarchist.

>> No.1614154

What? Do you live in a Muslim country something?

>> No.1614155

>>1614152 Pay your alcohol taxes Ivan.

>> No.1614157

I used to live in Russia. Yeah, you could buy 95% ethanol, but now only IPA.
First, I'm moved to shithole where you can buy ethanol in fucking walmart. Second, no. Booze must be tax free.

>> No.1614158

Excellent, thanks. Will investgate.

>> No.1614168

>how much stuff can I fit in a 4x4x2cm box
one deep, with proper courtyard, about 520 resistors before a stereo microscope becomes a very good idea :^)

>banned ethanol
the USA tried that once. didn't work out so well

>from high-grade everclear
>to India Pale Ale
пyтин нeт!

>> No.1614171

ahh i get it
even r1k (3.3mA) it still has mini offset .
Thank, anon

>> No.1614174

>the USA tried that once. didn't work out so well
Russia too, but it didn't work well too. Instead of drunk gopniks, they got blind drunk gopniks, since they were drinking brake fluid (soviet cars had alcohol based one for some reason at some point, which doesn't make sense).
>пyтин нeт!
Пyтин пидop и нe мoжeт пepecтaть cocaть хyи.

>> No.1614182

>want to read up on differences between thermistors and thermocouples
>go to first google result
>wow ntcs are better in almost every way
>notice the page is from a manufacturer that specializes in NTCs

almost got me

>> No.1614183

tdk right?? haha

>> No.1614184

NTCs are easier to use though. You can make thermostat with them with only two components.

>> No.1614248
File: 27 KB, 584x401, Annotation 2019-05-21 043055.jpg [View same] [iqdb] [saucenao] [google] [report]

What about this fix??

>> No.1614262

it would be better to just transmit the pulses digitally through the opto and filter on the output side

>> No.1614268

but I need current though

>> No.1614288

>how much did you want?
>10ccs for $36
fuck no

>> No.1614295

pretty sure that's 10x10ccs for $36

>> No.1614309

It's still pretty bad compared to rosin paste.

>> No.1614336

If size is a concern, you should probably just order your own custom PCB.

>> No.1614338

digispark my bro

>> No.1614341
File: 2 KB, 749x367, hot_seat_schematic[1].png [View same] [iqdb] [saucenao] [google] [report]

Hey guys I want to make a shocker project, and I grabed a harbor freight electric fly swatter, I did some googling and came across a sparkfun blog that I believe uses the same schematics.

>pic related

I am wanting to do similar project someone did, called shock potato, but make it smaller.

I figured the components from electric fly swatter would be sufficient, but my question is, is it possible to give it some more umpf? I want to use a coin cell battery to power it, I don't know if thats possible, I mean yeah it can be powered by two D cell batteries, but I am sure other things are factored in. Maybe adding a capacitor, and then have the capacitor discharge when contact is made?

>> No.1614346

I don't think I'd need a PCB for this where a simple protoboard would work. It's not much more than a 555 timer, a cap, and a resistor.

>> No.1614407

People usually use a larger output capacitor to increase the punch of those things. Messing about with the passives on the primary side of the circuit might increase the frequency, which would usually increase the amount of magnetic flux being coupled.

If it runs off a battery I'd think twice about using a 555, their quiescent current is awful thanks to having 3 5kΩ resistors in series from Vcc to GND.

>> No.1614435

>If it runs off a battery I'd think twice about using a 555, their quiescent current is awful thanks to having 3 5kΩ resistors in series from Vcc to GND.
Planning to run on a microUSB or similar 5V from my PC.

>> No.1614436

you can increase the umph by using a bigger storage capacitor, C1. you can technically use a coin cell to generate the charge but you'll probably have to make a custom circuit because those cells can't supply much peak current.

>> No.1614458

is there a preferred Arduino IDE for Linux besides the official one?

>> No.1614463

In that case it's fine. Though I hope you have some of the 2-pin micro-USB sockets, as the 5-pin ones are a bugger to solder.

>> No.1614520

it says it only contains rosin and ethanol

>> No.1614522

I'm pretty sure buck boosters can't go rail to rail, if you feed 3V in can you get 3V out for example?
but if it can take 3 - 5V in and shit out 3.3v out at all times that would be perfect

>> No.1614555

A buck-boost converter can do the 3V-5V > 3.3V conversion. But personally I'd consider using a boost converter to 5.5V or more with a linear regulator to drop it to 3.3V for optimal ripple rejection, or a buck-boost converter to kick it up to 4V or so followed by a linear regulator if that would be more efficient.

>> No.1614560

>boost converter to 5.5V or more with a linear regulator
interesting solution
but that requires two extra parts instead of just one and it would be wasting a lot of energy which kind of sucks with battery power (and i can't use more batteries in series to raise the voltage without the booster)

>> No.1614561

If the ripple from a normal switching converter is fine then there's no reason to add an extra linear stage. But dropping 0.5V or so with a linear regulator wouldn't be too bad for your efficiency if you went for a buck-boost and some 3.3V LDO.

>> No.1614563

i bought a roll of lf33 ldos which i'm going to use, the booster is about 85% efficient? i guess so with the ldo i am looking at about 20% energy waste? i guess that isn't too bad and it will save me from having to do extra fuckery like using opamps and mosftets to bypass or not bypass the regulator on the IC VIN depending on the battery charge state

>> No.1614569

If you can buck-boost it to 3.8V, then the 0.5V drop will be a 13% loss in the LDO. But LDOs operating at such low voltage drops tend to have worse ripple rejection, so I'd mess about with an oscope until you can make a decision. Or just run your circuit off a buck-boost converter and see if it likes it. The 5.5V boost method would mean losing 40% of your power across the LDO, which wouldn't be very nice for something with a battery on it.

Your LDO has a dropout of 0.45V at minimum, so you'll need to feed it at least 3.8V or so. But perhaps your circuit elements can run off lower voltages, like 2V. I know half my MCU ICs can run that low. If so, it would be a simple matter of using a buck converter or LDO to take it from 3-5V down to 2.5V or lower, assuming you can get such an LDO.

>> No.1614611

Ugh no, if you are feeling hardcore you can just use the MCU without the arduino bootloader

>> No.1614653
File: 926 KB, 2160x3840, IMG_20190404_155201.jpg [View same] [iqdb] [saucenao] [google] [report]

i'm a brainlet but can use a soldering iron, i have an old thinkpad and cant find oem or chink batteries anywhere so think i need to cell swap. I cant find any info on the batteries inside the oem battery. Would it be safe to swap these with 18650s?

>> No.1614654

On this note, what software/IDEs do people here use to write code for AVRs? And then what hardware/dongle do you use to program them? The USBASP things I'm seeing on ali have 10 pins on them, which sounds a bit large but I guess it's meant to be flexible.

>> No.1614662

They use 18650s but the Thinkpad batteries are glued shut and the cells inside are spot welded on tabs. It's almost impossible to replace the cells non-destructively.

>> No.1614663
File: 607 KB, 1414x2000, 1558206289968.jpg [View same] [iqdb] [saucenao] [google] [report]

this is a very old thinkpad that pic i posted is the internals of the battery, I have no idea what type of cell those are and they have no writing on them

>> No.1614665

Question about microcontrollers, and LED drivers. A while back, I bought a kit that used a PIC16F1783 controller (preprogrammed) to drive an LED array. The kit suggests blue LEDs will work, but none of my blue/white LEDs are lighting. I tried lighting one on a breadboard, and it will not turn on until ~2.3V. When I measure the output on a scope though, the highest peak only goes up to 2.0V.

Aren't LED drivers supposed to up the voltage to any arbitrary level, while keeping current at say 15mA? If so, why isn't my LED lighting? The accompanying resistor is only 100ohms, that should be more than doable for a 5v output. Would the programmer be setting some kind of internal limit? Or does the fact that it peaks at 2.0V imply the problem is elsewhere (say, at a red or green LED)? I can provide handdrawn schematics if needed.

>> No.1614671

>>1614665 Check your mcu power supply. Is should not dip bellow 3.3v when all leds are lit.

>> No.1614692
File: 159 KB, 1280x720, hosico.jpg [View same] [iqdb] [saucenao] [google] [report]

Anyone here know stuff about bootstrap gate driver???

>> No.1614693

This is lawnmower switch. What is that white shit for?

>> No.1614694
File: 374 KB, 1536x2048, IMG_20190521_165748.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1614695

Smooth as the day it was born. Although I just found a 5V rectangular spike at one of the negative data pins, lol.

>> No.1614696
File: 391 KB, 1536x2048, IMG_20190521_170121.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1614702

Total amateur here, but my guess would be a film decoupling capacitor to get rid of switch bounce

>> No.1614704

Why would a lawnmower need debouncing? Three is no ic there

>> No.1614729

Buck converter. Once the input drops below the threshold voltage, the duty cycle will sit at 100%.

A 3x063 isn't a great choice for a low-dropout buck converter. Using the internal transistors is going to add 2 diode drops. So you need an external switch; either that needs to be PNP/PMOS or you need a high-side driver.

A dedicated buck converter IC (e.g. L5983) would be better, although you probably aren't going to find one in through-hole.

>> No.1614741


that kind of motor will generate high-voltage sparks when you switch off. the white cap will eat some of that energy so the switch is less harmed and lives longer.

>> No.1614755

Hit up www.microchip.com
They bought out Atmel a while back and are slowly integrating the uC's into their development suite.
The Atmel Studio 7 IDE is still avaliable, but MPLABX is now supporting some AVR's.

Same goes with programming, old hardware can still work, but the newest generation of programmers/debuggers should include AVR functionality.

>> No.1614758

I just use avr-gcc to build, avr-binutils to link etc., avrdude and USBasp to download into the chip
the 2x5-pin callout is an Atmel standard, there are adapters to a 2x3-pin callout as well

unfortunately, "driver" has come to mean both dc-dc converters and mere power switches

>A 3x063 isn't a great choice
fixed kek
you are correct on all accounts. that said, that OP wasn't so concerned about performance as about low-end manufacturability

>> No.1614858

But you better solder them fast, otherwise plastic rigie goes melty-melty, and battery goes shorty-shory without any protection.

>> No.1614860

Acetone, or even better, gasoline on seams?

>> No.1614867

yeah ive soldered them for stuff before, just not sure if the batteries will be okay to swap as i have know idea what voltage they are

>> No.1614869

Those are probably Li-ion cells with same voltage range as modern 18650, so I think yes.
Check label, divide voltage by number of cells in series, if you got 3.6-3.7V - you're safe.

>> No.1614872
File: 705 KB, 700x932, 1558244027095.png [View same] [iqdb] [saucenao] [google] [report]

the batteries have no labels on which is why i asked kek, thankyou for the help guess ill jsut order some cells and try it out

>> No.1614914
File: 133 KB, 1007x763, USBasp_PinoutVisual.jpg [View same] [iqdb] [saucenao] [google] [report]

wow this 10-pin standard is inefficient as fuck

>> No.1614924

imagine that there's a ribbon cable with IDC connector plugged into it, and consider the layout of the signals on the wires. note especially that every signal line has a ground return (or two) as close as possible, for best signal integrity and improved emissions. it's been fairly commonly done with dual-row connectors since at least the 1970s e.g. floppy and hard disk interface cabling from the late 1970s

>> No.1614925

yes but I'm not exactly uploading code at 500MB/s
they should just use coax like the cool guys

>> No.1614962

Thanks for the help, I took a look at the writing on the capacitor, and this is whats written on it.

>224j f

the gap between "224j" and "f" is intentional. IDK what the represents, but I added it just in case.

So I did a google search on 224j capacitor, and it showed me similar looking capacitors on amazon, with higher volt rating, 640v for example. I did a full search on "224j 400mpsa" and didn't get much unless I switched it to "224j 400vpsa"

I am guessing the 400 means 400 volts?

Also what can I check or do, to see the max voltage the circuit can take without frying it?

>> No.1614964

224 means 22 and 4 zeroes = 220,000pF = 220nF. The j and f are tolerance and maybe temperature ratings.
400mpsa.2 probably refers to voltage. I'd throw in a 470nF or 1uF class-X capacitor as a replacement.

>> No.1614968

son, that starts to matter at several MHz

220nF capacitor, ±5%
>400 volts
probably, the 630V or 1000V would probably be better for replacement if you're going to up the value
if it were "MKS" it would indicate a polystyrene dielectric

>> No.1614976

Ok, I'm faced with a few different oscilloscopes I could walk home with:
>100MHz Hitachi VC-6545 Digital Storage Oscilloscope
>100MHz Hitachi V-1565
>50MHz Hitachi V-552
Since the 6545 has "save", "hold", "storage", etc. not directly off the traces but with an ADC in there. I didn't think it would be an issue, and that it might be beneficial to be able to pause the trace, but someone more experienced than I stated that he'd rather have a more analog model since that would mean no quantisation error among other things.
Does anyone here have an opinion on these early digital storage oscilloscopes compared to their forebears? I'm currently scouring their service manuals for anything akin to a block diagram that shows an ADC on it, but it's slow work.

>> No.1615072


come on, now, a DSO is always better. some things just cannot be seen otherwise. the lack of smooth waveforms is a minor point by comparison. (find a yng boy and admire his smooth hairless curves instead.)

>> No.1615104

Well both have CRT screens. I ended up getting the 6545/DSO one since after some testing I figured out the "real time" digital mode was something that could be toggled. It also has surprisingly good cursors and a frequency readout and what, so I think I made the right decision.

>> No.1615105
File: 139 KB, 631x577, Annotation 2019-05-22 123858.jpg [View same] [iqdb] [saucenao] [google] [report]

It is too messy for 3 Amps???
The PCB size is 10mm*10mm

>> No.1615109

Looks like some of those traces could be made shorter, like VS12. Also I might consider putting multiple vias to join those lower traces on VS34 instead of just one on each side. Also in general the clearance distances you've given aren't very consistent, especially VS34 with U3 and those red traces in the middle that are basically touching one another. I'd see about making your circuit a little more compact and more linear, since there's a big void in the middle and I bet a lot of parts could be positioned somewhere more efficient. Like R4, make it point in the same direction as R5 to shorten that backside trace going to U3. In fact I'd start placing components all over again, since it doesn't look like enough effort went into choosing where they go in the first place. But I'm no expert.

I also find your adherence to 90% THT parts with only 5 SMT parts unusual.

>> No.1615111

to carry 3A at a 5°C temperature rise on 1oz copper, you need a 2.1mm track width, minimum, which will drop 70mV per 100mm length
as long as you dont have excessive inductive or capacitive feedback that matters for your circuit (not really feeling a full design review rn), and your traces are separated widely enough (see IPC-2221 or a derivative for spacing guidelines by voltage) it will probably work, but extra layout effort would be well repaid

>> No.1615113

imo SMT elcaps are more pain than they're worth for hand assembly

>> No.1615114

Yes but why THTs for all the ICs and most of the other passives? Why use any SMTs at all at that point?

>> No.1615116

But it's an ac motor, wouldn't that cap just cause a short?

>> No.1615119

Capacitors have a finite impedance to AC, the actual current drawn won't be too high at all. Perhaps on the order of a dozen mA. And in normal operation this impedance will actually cancel with the AC motor's impedance and cause the whole thing to draw slightly less current.

When the switch suddenly breaks the circuit, you'd usually have a freewheel diode to stop the inductive kickback from arcing through your switch in a DC motor. Look up how this works if you're unfamiliar. The same applies to an AC motor, but they'd have to use two HV zener diodes in antiseries to get the same effect since the voltage goes 170V above and below the neutral line in normal operation. This circuit would result in a significant power being dissipated in the diodes themselves since they'd have a >180V voltage drop across them, where a single diode in a DC motor circuit would only have 0.7V or so across it, the rest being across the motor windings' resistance. So instead we use a capacitor, which absorbs the energy stored in the windings and rotor, and bounces it back again in the other direction (and again and again), without dissipating much energy as heat at all. Ideally the motor windings will have much higher resistance than the capacitor, which can usually be assumed to have an ESR significantly below 1Ω, resulting in the vast majority of the power being dissipated in the motor windings, which is fine because of how large they are and how much room to radiate and convect away heat they have.
This capacitor would also work on a DC motor, but the driving circuitry for a DC motor would likely not be hardened against negative voltages, and the capacitor would result in a much more negative voltage (some significant fraction of the main driving voltage) than the diode (-0.7V or so).

>> No.1615120

that may be a question of what that anon bought off alibay and has in stock. for me it usually is

capacitive reactance decreases with increasing frequency and increasing capacitance: Xc = 1/(2*pi*f*C)
the reactance of a 1µF cap at 60Hz is ~2700 ohms. reactance at 60kHz is 2.7 ohms. mains frequency currents would pass poorly through the cap, but sharper spikes (harmonics reaching into the tens or hundreds of kHz) would pass very well through the cap

>> No.1615122

>what that anon bought off alibay
So he's either in the awkward transition stage between THT and SMT, or he found some parts are only available (at a reasonable price) in SMT? Well I guess bought some SMT SA602s for the latter reason, but since fab houses usually want you to order like 20 copies of your board I'd think you'd be buying parts specifically for the board anyhow.
Also I just noticed there's not much in the way of bypass caps near his ICs.

>> No.1615130

>Buck converter. Once the input drops below the threshold voltage, the duty cycle will sit at 100%.
Do all bucks work like that? that if you supply less than required minimum voltage they will become "shorts"?

>> No.1615133

it's been my experience that the chink proto houses are fine with 5-orders. they probably make 10 and toss the other 5
some, perhaps. but if you've got fifty of "everything" somewhat organized in bags in boxes behind you, for repair and for new construction, the only things you'd really need to order are unusual ICs and maybe some 1% resistors

no. some observe a maximum duty cycle or minimum off-time

>> No.1615146

if you don't mind the base getting a little melty they're fine with paste + hot air gun or just iron on each side.

>> No.1615149

>no. some observe a maximum duty cycle or minimum off-time
isn't that the same thing? maximum duty cycle would be just on all the time and minimum off time means also on all the time

>> No.1615216

He means some have a maximum duty cycle less than 100% and/or a minimum above 0%.

Simple hysteretic buck converters will naturally do 100% duty cycle if they can't achieve the threshold output voltage. The L5983 mentioned specifically states "Low dropout operation: 100% duty cycle".

The 3x063 can't do 100%, and isn't particularly good for buck converters anyhow.

A buck converter has the switch on the high side, so to obtain saturation you need either a PNP/PMOS switch or a drive voltage a few volts above the input voltage. For the latter option it's common to use a voltage doubler driven from the switched output voltage, but that won't work if the converter is running at 100% duty cycle.

>> No.1615352

sorta. not all converters are PWM machines. some use pulse-frequency modulation at low loads, PFM at all loads, or a hysteretic switching scheme. therefore it doesn't make as much sense to characterize PFM or hysteretic switching relative to a cycle that isn't part of the calculation

>> No.1615383

no. some converters have a max duty cycle of 90-95% in order that the output switch is never continuously on. particularly for boost converters, that would be catastrophic. similarly, converters in PFM mode vary the on- or off-time to regulate the output, while holding constant the other time

>> No.1615437

>drilling my first holes in aluminium enclosure for guitar pedal
>drill fucks off on me when drilling pilot hole despite center punching it
>hole is several millimeters off
Guess drill presses aren't a meme.
Maybe I should get a new drill bit first though.
On the other hand, I'm amazed how well a $2 chinesium step drill bit cuts through it like butter.

>> No.1615459

Fuck drilling aluminum, especially the thin bullshit. I've raged so many times doing the same thing

>> No.1615461

I mean yes

that is correct. ditto deburring tools, but mind your hands when using them

>> No.1615463

let's say I have 4 oscillators running off of a 40106
how would I mix the 4 signals together without exploding something
send them all to a common rail with diodes on each output?

>> No.1615475
File: 21 KB, 274x271, 1543740200237.png [View same] [iqdb] [saucenao] [google] [report]

feel free to use the op amp of your choice

>> No.1615500
File: 2.96 MB, 4160x3120, IMG_20190522_231145368.jpg [View same] [iqdb] [saucenao] [google] [report]

Noob here trying to build an AND gate.
Resistors are all 10k apart from LED one which is 250ohm.
It works, but when the right button is pressed by itself 0.2mA and 1.7v gets passed through, dimly lighting the LED.
How do I stop this?

>> No.1615501
File: 2.79 MB, 3120x4160, IMG_20190522_231243010.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1615513

The preferred language of electronics is the circuit diagram.

>> No.1615519
File: 41 KB, 577x521, 1552877144549.png [View same] [iqdb] [saucenao] [google] [report]


>> No.1615522

Probably some leakage current
consider this >>1615519

>> No.1615542

Works perfectly, thanks anons, I can see how this avoids the problem because the leakage current now just leaks to ground instead of through the LED.
I'm still a bit confused on how I would make use of the output in this "component before the transistors" configuration though. Obviously it works with an LED because the transistors connect it to ground, but how would it work for an IC? If I wanted to pull an IC pin high with this AND gate, where would I place it in this circuit while still avoiding leakage current?

>> No.1615552
File: 8 KB, 400x400, tegaki.png [View same] [iqdb] [saucenao] [google] [report]

>shitty tegaki drawing

i'm pretty familiar with the op amp regulator topology, but i don't know anything about representing it mathematically. i want to be able to work out the transfer function for this system and write out the bode plot by hand, so i can understand how to optimize it. are there any good short form web sources on how to do that? i took differential equations in college but i don't remember a single thing from it.

>> No.1615555

also if this is something i can't really learn without having to open a textbook then that would also be helpful to know so i don't waste my time.

>> No.1615601

Just spice it? You could give the calculations a shot, but it wouldn't be terribly nice looking. I'd start with the simplest version of that regulator (i.e. without superfluous capacitors and such) first.

>> No.1615604
File: 30 KB, 439x521, 1549478896612.png [View same] [iqdb] [saucenao] [google] [report]

it's not actually leakage current. it's base current. it's supposed to flow and is essential to transistor action. if you were using n-channel MOSFETs instead of BJTs (which are voltage-mode), you would not be seeing that effect. you'd be seeing a slightly different one where the source voltage is some volt or two above the gate. that's why logic implementations tend to prefer placing the
anyway, as regards voltage levels, what you have now is an open-collector NAND gate. add a pull-up, then negate the negation with an inverter stage with its own pull-up

also interested in network analysis and would like to know this

>> No.1615671

is there a book on practical circuit design and practical circuit knowledge?
The Art of Electronics is good and all, but I want to learn shit like how to design a portable charger from 18650s, how to design an audio amplifier, what makes one implementation of a circuit better than another, etc

>> No.1615693

as long as a circuit meets specs, some figures of merit include area, cost, size, insensitivity to manuacturing variations, operating margin, tolerance to abuse (e.g. ESD), etc. the importance of each of those figures of merit varies by application and industry
consider just looking at existing circuits or ICs that do those things, especially those that include detailed documentation of what's happening when and why. you will gain some understanding of the parameters that are important to your design and be able to select parts for your design. much of the design process is just taking standard topologies, selecting components for them, and integrating them into a finished whole

>> No.1615714
File: 1.36 MB, 3264x2448, newtronics 200ms.jpg [View same] [iqdb] [saucenao] [google] [report]

Ooh, looking inside my new/old function generator it's got some CDIPs in it. Namely: MC1445 amplifier and 10116 line receiver(probably being used as a comparator). There's also a large PDIP ICM7216 that's a dedicated frequency counter and 7-seg display driver, and the entire board is covered in aesthetic curly traces. Also some of those pots are really cantilevered. And the central potentiometer has a gearbox in it because the knob can be rotated multiple times before the pot inside hits the end of its range. On closer inspection, the gearbox has to be inside the knob itself, as there's no room elsewhere.
The model is a Newtronics 200MS.

I'll get around to posting the internals of my scope later.

>> No.1615732

if transistor amplifies the base current, what happens if you say supply 10ma on the base which results in 10A through the transistor, but the connected load only needs 500ma? will the transistor force 10a through the load?

>> No.1615742

If your mains socket can supply 10A but your 100W light bulb only needs 1A, will the socket force 10A through the bulb?

>> No.1615743

>will the transistor force 10a through the load?
the transistor would be creating energy in that case and fossil fuel companies would be on suicide watch
when the base current * beta > collector current as externally limited, the transistor is operating in the saturation region. there, Vce has a sublinear dependency on collector current, often specified in the datasheet. a BJT takes quite a bit of time to desaturate and reenter the active region (which may matter to you if microseconds matter to you)

>> No.1615748

KiCAD v6 roadmap:
>- Study ergonomics of various commercial/proprietary PCB applications (when in doubt about any particular UI solution, check how it has been done in a certain proprietary app that is very popular among OSHW folks and do exactly opposite).

>> No.1615749

Step 1: Steal from competition

every roadmap ever

>> No.1615751

>proprietary app that is very popular among OSHW folks
What are they referring to? EasyEDA or something?

>> No.1615753

I figured EAGLE

>> No.1615763

eagle is a joke nowadays

>> No.1615772
File: 350 KB, 1405x1152, 1-1.jpg [View same] [iqdb] [saucenao] [google] [report]

Here's the scope in analog mode:

>> No.1615773
File: 335 KB, 1336x1142, 2-2.jpg [View same] [iqdb] [saucenao] [google] [report]

And here's it in digital mode:
Pretty nifty if you ask me.

>> No.1615798

uh oh.. i just accidentally took a sip from a water glass on my table and then realized it is the same glass i used to wash my etched pcb in, to clean it from fecl3
am i in some legit danger? nothing seems to hurt and it was just a small sip, but i did swallow unfortunately

>> No.1615800
File: 11 KB, 440x118, 440px-DB25_Diagram.svg.png [View same] [iqdb] [saucenao] [google] [report]

And this scope has an RS232 port on the back of it, which is where I assume you can extract the stored data. Trying to interface with it with custom hardware might be fun. If anyone here has experience with this I'd love to hear from you.
Haven't figured out a few of the features though, namely what exactly the horizontal mode switches (A, Alt, B, where Alt + B = X/Y) do, and what the Mode switch does (Auto, Norm, TV-V, TV-H). Perhaps the TV modes are used for troubleshooting a TV's vertical and horizontal scanning, so you'd be able to look at the sawtooth waves and see what's what.

I also saw a neat video on hackaday where someone used the VGA port on a computer as a DAC (combined with 3 resistors on a tiny PCB) to feed an oscilloscope's X and Y channels with data to display vector images, animations, and even live games. Turning this oscilloscope into a vector screen for my raspberry pi could be interesting, if I could actually pull it off.

Got any boric acid to wash it down with?

>> No.1615802

There's already ferric chloride in your tap water.
If it's watered down it's not dangerous.

>> No.1615803

>i just swallowed heavy metals, how many new livers do i need?

>> No.1615804

>There's already ferric chloride in your tap water
I bet it's used in less than 10% of places with treated water.

>> No.1615806

It's a pretty common flocking agent, it's not some leaded American tap water third world thing.
Have you checked your local sewage treatment report?

>> No.1615807

>Have you checked your local sewage treatment report?
all lies. do you really think the gov admits they are putting stuff into water to turn the populace more obedient?
the only report you can trust is the one where you perform the tests yourself

>> No.1615833

Thanks very much, your diagram makes sense, I'll try it out when I get home from work.
You missed off the end of this sentence here though, can you clarify what you meant to say?
>that's why logic implementations tend to prefer placing the

>> No.1615835

Ever heard of diode logic? For cases where you aren't having more than 1 or 2 gates cascaded it might be the better method, at least as far as ANDs and ORs go. Something about putting two NPNs in series like that doesn't sit right with me.

>> No.1615849

I noticed that industrial ICs which are supposed to run for years on battery use all some sort of purple batteries. What sort of magic is that? Are they different from regular lions?

>> No.1615860
File: 4 KB, 259x194, lithium.jpg [View same] [iqdb] [saucenao] [google] [report]

Long life lithium primary cells (not rechargeable), many colors, incl. purple.
>What sort of magic is that?
Selective perception; "all", see?

>> No.1615863

For most purposes, the transistor in that circuit can be modelled with just Ve=Vb-Vbe, with Vbe constant. If that isn't enough, there's the Ebers-Moll BJT model, but if you use that you won't be able to solve the system analytically.

An ideal op-amp is modelled as V+=V-, and the rest of it is network analysis (which gives you a system of linear ODEs).

>> No.1615877

Hmm, ok. I've heard of diode logic but I don't know anything about it, I'll do some research later.
Do you know of any good online resources that walk you through creating different types of logic gates, or are books the best place to learn about this stuff?
I know none of this is practical in modern circuits because ICs exist, but I find it very interesting.

>> No.1615891

If I have a 12V linear regulator that can take say 15-32V input and I just rectified say 20VAC.
Would the regulator have any issues if I didn't do any smoothing after rectification?

>> No.1615908

Yes. Rectified AC will be zero near the zero crossing, and a linear regulator can only reduce the output voltage below the input, it can't increase it. So you'll get (roughly) a rectified sine wave with the peaks chopped off. The filter capacitor needs to hold enough charge that the voltage never drops below the regulator's minimum voltage even when the rectifier output is below that level.

>> No.1615914
File: 142 KB, 1176x886, Annotation 2019-05-23 233931.jpg [View same] [iqdb] [saucenao] [google] [report]

Is this just a simple inductor or there is something more??

>> No.1615918

...input transistors' emitters/sources against a fairly solid voltage (with the notable exception of TTL which uses a common base arrangement for its inputs): so input levels aren't state-dependent

if you understand the components, you can walk yourself through it. just look at a particular logic family and trace currents/voltages through each possible set of inputs x state of the circuit
you might try a university text. I learned a few things from Roth's "Fundamentals of Logic Design"

>> No.1615940
File: 17 KB, 670x663, schematic.png [View same] [iqdb] [saucenao] [google] [report]

Here I have a lipo battery voltage indicator with a comparator that has hysteresis
because of that the base current is at like 10uA according to falstad
now I never manage to saturate my transistor and because of that the voltage at the emitter never reaches 5V but 3.7V according to my measurements on my irl test circuit
what can be done here?

>> No.1615943

Btw the transistor in my test circuit is a bc547. I'm okay with 3.7V but I'm afraid that the smd transistor in my schematic will not be able to supply that voltage. I don't really understand its datasheet

>> No.1615951


>> No.1615953

What do you expect the circuit to do?

>> No.1615959

You can treat the two transistors as almost identical.

>> No.1615966


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