/ohm/ - electronics general, tripping the LED light fantastic edition

[Anonymous No.1382101]

completed thread: >>1377579
>I'm new to electronics, where to get started?
There are several good books and YouTube channels that are commonly recommended for beginners and those wanting to learn more, many with advanced techniques. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty.

>Books?
Beginner:
Forrest Mims III, Getting Started in Electronics
Charles Platt, Make: Electronics
Michael Jay Geier, How to Diagnose & Fix Everything Electronic

Intermediate:
Kybett & Boysen, All New Electronics Self-Teaching Guide
Paul Scherz and Simon Monk, Practical Electronics for Inventors

Advanced:
Paul Horowitz and Winfield Hill, The Art of Electronics

>YouTube?
mjlorton
paceworldwide
eevblog
EcProjects
greatscottlab
AfroTechMods
Photonvids
sdgelectronics
TheSignalPathBlog

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

>Components/equipment sources?
Mouser, Digi-Key, Arrow, Newark are global full-line distributors with small/no minimum order.
eBay/AliExpress sellers, especially good for component assortments/sample kits (caveat emptor)
Independent retail electronics distributors
ladyada.net/library/procure/hobbyist.html

>Circuit simulators?
This mostly comes down to personal preference. These are the most common ones though:
LTSpice
CircuitJS (quick, dirty, interactive)
NI Multisim
CircuitLab
iCircuit for Macs

>PCB layout software?
KiCAD (recommended)
CircuitMaker
Circuit Wizard
Various high-end commercial offerings (Altium, etc)

>My circuit doesn't work. Halp?
Check wiring, soldering, part pinouts, and board artwork if applicable, then post schematic. Supply ALL relevant info and component values when asking a question.
>Li+/LiPo batteries
Read this fine 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.

[Anonymous No.1382102]

this thread's digits brought to you in part by the MIC2101 38V synchronous buck controller (15A output!)

[Anonymous No.1382123]

>>1382102
ooh, Hyper Speed Control®

[Anonymous No.1382125]

[Anonymous No.1382127]

>>1382064
Opamp differentiator or integrator? You may need some sort of AGC if you're having a wide variance in sine frequency, but stay well behind (the limited gain zone) and the phase will remain pretty damn constant. An integrator is probably the best way to go for stability reasons. At w = 1/RC your circuit will have a gain of 0dB, higher with increasing frequency for a differentiator and lower with increasing frequency for an integrator. Slope of ±20dB/decade respectively.

[Anonymous No.1382130]

>tfw my physics electronics textbook includes a capacitor-ramp ADC circuit

[Anonymous No.1382147]

>>1382127
Using an integrator for the signal but then also having a differentiator in parallel leading to a functionally ideal rectifier and a capacitor would get an DC voltage equal to the inverse of the amplitude of the integrated sine, so throw the two into a mixer and you've got yourself a constant-amplitude multi-frequency phase shifter, but it's a pretty awful circuit. Not as bad looking as >>1382128, but likely much less stable. Also ideal diodes are possibly a pain in the arse, but can maybe be avoided if you ensure that DC voltage is always an order of magnitude larger than the diode drop, which would be an issue with the ring mixer in either case. I've never seen ideal diodes being used in mixers so there's probably a good reason for that. And I mean opamp ideal diodes.

[Anonymous No.1382172]

Really basic question but no-one on /g/ was any use. Is it obvious what kind of LED should go onto those diode-marked pads (e.g. is there an obviousstandard type/size for this kind of stuff), or would I have to get more information about this specific PCB from the seller?

Apologies for rather shitty photo

[Anonymous No.1382230]

Does anyone know any good resources for learning VHDL? Similar to something like code academy or just a step by step on developing something very small. (entity, architecture, process etc) My university's resources are fairly limited and they cut the coursework requirement for VHDL this year, yet 20%of the exam papers are on it.

>>1382172
Any LED will do if theres a resistor on the front side of the board. If there isn't, put one in series with either of the pads.

[Anonymous No.1382250]

>>1382172
>or would I have to get more information about this specific PCB from the seller?
do that.

>>1382230
So you think there's a possibility that poster got a board that has empty pads for LEDs, but does not have any provision for current control?
Seems unlikely.

[Anonymous No.1382262]

>>1382250
It could be incredibly bad Chinese knockoff crap

[Anonymous No.1382265]

>>1382064
Wikipedia All-pass_filter

[Anonymous No.1382272]

>>1382230
> Any LED will do if theres a resistor on the front side of the board.
This is for a keyboard so the other side is completely empty of components since that's where the switches will go. It's supposed to be a "ready to use, just add LEDs and switches" board so I'm assuming they're connected to some of the resistors sprinkled around the underside. It's also well reviewed from a supposedly trusted seller so >>1382250 is probably right

I ordered https://aliexpress.com/item/penis/32788331922.html because it looks about right but I'll double-check with the seller.
Thanks for the advice guys

[Anonymous No.1382285]

>>1382272
>https://aliexpress.com/item/penis
lmao

[Anonymous No.1382307]

>>1382285
I never know what to put there after cutting out the long-as-fuck actual description

[Anonymous No.1382320]

>>1382307
I'm actually glad that's catching on

>>1382272
it looks like those pads are designed to allow for a few alternate packages. maybe the 6-pin pads are for 5050 LEDs of your choice of single-color. 3528s could probably fit on the inner parts of those pads. the best bet would have been to measure

[Anonymous No.1382324]

What does u1a, u1b, u2a, etc. next to op amps in circuit diagrams stand for?

[Anonymous No.1382325]

>>1382324
unique identifier
U = component type, U is usually an integrated circuit
1 = the first U in the circuit
A = if multiple units within the integrated circuit, this identifies which one

[Anonymous No.1382388]

Newest of newfags to electronics. My library only had one of the books in the OP. How's this for a starting point? Strongly considering electronics engineering associate's in the fall.

[Anonymous No.1382401]

>>1382388
YouTube is your friend.

[Anonymous No.1382404]

I'm trying to brute-force the pinout of a 3-digit 7 segment display using jumpers and a power supply at 3.3 volts

I think I'm burning the LEDs out though, because they will flash and make the characteristic sizzle of a burning LED. Why are they burning out at 3.3 volts?

[Anonymous No.1382408]

>>1382404
yes, you are, because your 3.3V supply isn't current limited

[Anonymous No.1382409]

>>1382408
looks like I ruined a perfectly good display then, awesome. Should've added a resistor.

[Anonymous No.1382420]

>>1382320
I mean I don't regret ordering those since they're $0.40 or something, but I just grabbed a ruler and came up with:
>2mm between the pads
>each pad a bit under 3mm long, with the teeth being around 1mm of that
>the entire thing is something like 4.5mm wide
Like I said (or rather implied) I'm new at this so that doesn't tell me anything. Does it to you?

[Anonymous No.1382490]

>>1382409
65Ω minimum resistance, for random testing, so throw a 100Ω in there and you'll easily be able to see when an LED is lit. 7-seg drivers and some BCD-to-7seg decoders will include current sources (or sinks) for this purpose, though it is something to check.

A diode check mode on your multimeter will light those segments, and a resistance mode might also, albeit dimly.

>>1382420
Google some common SMD package footprints, I don't believe there are many (if any) package footprints solely made for LEDs. Those SMD packages plated onto those ebay PCB rulers might be an easy place to start.

[Anonymous No.1382492]

>>1382420
ah, well, good enough. they probably will fit just about anything

>>1382490
there are, though they usually derive from IPC standards (except for the 6-pin 5050s etc.) at least I've never seen any component but LEDs in a 3528 package

[Anonymous No.1382495]

Hey guys! I just graduated on Saturday and I've got an interview as an EE level 1 substation designer. I've been studying up on the topic, and bought a suit, but I'm still nervous. I always say something dumb during the interview. I am fantastic at phone interviews, but tend to spaz out in person.
Any tips?

[Anonymous No.1382522]

>>1382495
-talk slowly. it gives you more time to form your sentences.
-it's important that they hear you talk, so seriously have questions ready to ask them.
-if you're not outright lying already then be sure to overstate your role in every prior project you discuss. everyone does this, so if you don't it'll just seem like you were less involved in extracurriculars than those people.
-your interviewers know you're full of shit when lying/exaggerating about the above so keep plausible deniability. don't try to frame yourself as a genius, just a team leader.
-don't take it too seriously because it'll hurt your performance. when you have a job you'll realize how dumb it was to be stressing about not getting a job.
if you can't talk shop now, you won't learn in a week. no sense giving advice there imo.

[Anonymous No.1382586]

>>1382522
Wow, thanks man! These are some really good tips, especially about not getting to worried. I tend to do that.

It's an hour long interview, so I'm preparing for them to ask a lot of technical questions about my schooling.

I need to think of 2 or 3 questions to ask after the interview portion is over. Something that shows I'm genuinely interested. I had great questions for the phone interview, but don't know what else to ask in person.

[Anonymous No.1382609]

>>1382388
https://mega.nz/#F!4sBhWRba!4lXxQRbn48vhWCzClBhD-g

Thank me later.

[Anonymous No.1382613]

>>1382586
Well interest in co-workers is probably a good thing to show, as is interest in the company's long-term growth.

[Anonymous No.1382649]

>>1382613
>interest in co-workers is probably a good thing to show

good point. start by showing your interest by commenting on the rack on the secretary, and expressing relief that there arent too many black employees.

[Anonymous No.1382689]

>>1382649
Ask whether the staff barbecues are halal.

[Anonymous No.1382744]

beginner here.

As a personal project i want to use EEG to create a REM alarm clock, and other sleep monitoring/interfering utilities i am planning.
Theorically speaking i don't think i need a signal quality as great, as the one required for typical uses of EEG such as brain-computer interfaces, neither i should need as many ports.

i feel like i should be able to handle everything but designing a new board from 0, and i don't feel like wasting time and money reinventing the wheel, so what are my option for the board?
is it a better idea to buy a commercial product and scavenge it for the board , mod and rewire it, buy a ready to work board marketed at tinkerers like me, or copy the schematic from some opensource project, have it printed, buy the component and solder it myself?
Do you think it's wiser to search for a low end board that is able to just handle what i need or shoot for the higher end?
any brand you would suggest?
does shit liek this look any good https://www.olimex.com/Products/EEG/OpenEEG/EEG-SMT/open-source-hardware?

price is a concern but i know i won't be getting under the 100-300€ price range.

[Anonymous No.1382923]

Does anyone know why condenser microphones take +48v phantom power? I know why phantom power is necessary, I'm asking why did they land on +48v.

[Anonymous No.1382943]

>>1382923
Wikipedia Phantom_power

[Anonymous No.1382988]

I'm >>1382420 again, seller replied "3528 or 5050". That means the ones I ordered will work (they're 3528), but out of curiosity, is there any functional difference between the two that might make one better? E.g. noticeably easier to solder, or usually comes with brighter diodes, or something.
I appreciate this is really basic stuff, and I'll stop shitting up the thread after this

[Anonymous No.1383017]

>>1382101
is there any easy way to measure milliohms ?

I want to check the subohm resistance on vape coils , without having to buy a single purpose built meter .

Like I'd rather buy a soldering iron and some kind of kit to make something and maybe learn a bit in the process and have some product with more purposes.

Btw I figure the answer is no , but thought I'd ask

also have HFT meter that sucks

Anything from a simple circuit , to a ardunio kit that I can make do things.

I saw this guy mess around with pic's (Microcontroller ) and kits

https://www.youtube.com/user/julius256

also have a little background in 18650 led torches

I guess I'm asing for the longer harder aproach to a simple problem

also cheaper

go ahead and laugh now

[Anonymous No.1383019]

>>1382923
Presumably because:
Conductor size determines max current
<50v is pretty much considered 'safe' and gets you around lists of bullshit red tape and insurance.

So i would say it's the optimum choice to maximize available power through thin cables without killing anyone.

[Anonymous No.1383027]

>>1383017
Best I can figure is make a voltage divider with the coil and a reasonable known resistor such that you don't pull too much current or dissipate too much power through the resistor. That or just measure the current through it when it's being used, provided your DMM can handle it.
V = IR
P = IV

[Anonymous No.1383069]

I'm sending a binary pulse and trying to detect it is troubling me

I want to detect the beginning of the signal, but can't find the single shot option anywhere for the life of me

One way I've found to capture a piece of the signal is by reducing it's frequency, then after I see it's getting picked up on the scope, press the "single" button on run control (upper right) which freezes it in place. Pressing "single" BEFORE sending the signal results in nothing shown.

How to capture the beginning of the signal though? Trigger modes offer "auto" and "normal" mode, normal mode does freeze it in place but at a random point in the binary sequence

[Anonymous No.1383079]

>>1383069
Single button is what you want.
Go properly into the trigger options first, make sure you have it set up, the correct level, the correct input channel, the correct trigger type so rising edge, falling edge etc.
Trigger mode is a trick shouldn't make much difference at the end of the day, it's catching something perhaps the first bits of your signal aren't wide enough for how your trigger is set up or your timebase.

[Anonymous No.1383081]

Alright I'll try again tommorow, so set trigger type to rising edge, set trigger level, press Single, send the pulse and hope for the best

[Anonymous No.1383083]

>>1383081
Make sure trigger input is correct, probably channel 1 if that's what your using.

[Anonymous No.1383084]

>>1383069
Could whip up a circuit to feed the ext.trig input with a latch so it only triggers once, if all else fails. Not sure if those 2 or 3 gate delays would be a problem though.

[Anonymous No.1383101]

>>1383083
Will do, thanks

>>1383084
You mean just use a SR flip flop, and drive the set pin with the binary signal? That's an interesting thought, never used the ext trig input

[Anonymous No.1383110]

Hey I just realised that when I'm done with my shitty python programming of a truth-table to logic statement program (like half done atm), I could iterate through every possible input (up to a certain number of bits) and record every output of these, then make a truth table of all that, then put it through the code and generate myself an optimised truth table simplifier.

[Anonymous No.1383112]

How the fuck do I do this? I've only been able to figure out j1 since it's the inverse of the left side of the first k-map, but I can't figure out why the maps are partitioned the way they are in the first place, or how to get the functions written here.
I've been trying to do this all afternoon.

[Anonymous No.1383114]

>>1383101
>You mean just use a SR flip flop
Or an SR latch, D ff/latch, or even a SIPO shift register. Shift registers, man.

[Anonymous No.1383116]

>>1383112
Not seen Gray code in a K-map before?

As far as I remember you bring up the next-state truth table of the FF you plan on using and do some voodoo to fit your K-map expression to it. But I haven't done that in a couple of years. I'm pretty sure the Digital Fundamentals textbook includes an explanation for this, which is present in >>1382609 if you swing that way.

[Anonymous No.1383163]

>>1383112
Imo u dun goofed friendo. See pic. Im off to sleep might see 2moz.

[Anonymous No.1383265]

>>1383017
use an lm317 and a tl431 to make a 1A current source that runs off a wall wart or a 9v battery. then put that through the coil and measure the voltage across it with your multimeter. then do R=V/I

[Anonymous No.1383267]

>>1383265
>9V battery
>1A current source
gtfo

[Anonymous No.1383268]

>>1383267
9vs have 1-2 ohms esr. you can run that circuit just fine off 7v. also kill yourself.

[Anonymous No.1383272]

>>1383268
Standard/cheap 9V batteries will only go up to like 500mA, but if he has an alkaline (or lithium I guess) it should be fine.

[Anonymous No.1383277]

>>1383272
i had wondered about including the 9v in my post so i actually tested it. granted this is an alkaline, but i don't have cheap ones because i steal mine from work.

[Anonymous No.1383280]

>>1383272
0.5A is probably enough to get a reading on even a crap meter. A 3.5 digit DMM should be able to resolve voltages down to 10mV on the 2V range and that range should be standard on literally all meters, even the crappiest of chink meters.

Also he should use a current mirror with power BJTs and a resistor which is less complex than a lm317 and tl431. 0.7V*0.5A is what 350mW? The transistors will get a bit warm but should be will within the ratings of something like a TIP31.

[Anonymous No.1383285]

>>1383280
0.7V where? the pass transistor has to dissipate (9 - 0.x)V * 0.5A, which will certainly require a heat sink

[Anonymous No.1383286]

>>1383285
8.3V dropped over the load, 0.7V over the transistor.

[Anonymous No.1383287]

>>1383285
regardless he only really needs this circuit to be active for a few seconds. i found a number for thermal mass of a to220, and throwing some ballpark figures in suggests that you wouldn't even need a heatsink.

7W*5s/(0.54J/C) + 20C = ~85C

[Anonymous No.1383300]

>>1383287
maybe, as long as it's tightly thermally-bonded to the other half of the current mirror.
also 8.3V / 0.5A = 16.6 ohms, I think it's time for you to draw a picture

[Anonymous No.1383320]

>>1383277
>on 10A mode
>plugs in V/Ω sockets

>>1383280
Well I don't exactly see why the voltage reference is necessary, shouldn't it work fine enough with just the 317?

[Anonymous No.1383351]

>>1383320
It would but you do not even need it. All you need is a voltage source, a suitable current limiting resistor (measure its value) and your vape coil in series to it. The voltage across the resistor tells you the current and the voltage across the coil tells you its resistance. One milliohm = one millivolt per ampere.

[Anonymous No.1383354]

>>1383351
Well the average resistor has much less heat-dissipating ability than a TO-220, though I haven't done the calculation on the 1.25V resistor that makes the current source. Regardless, you'll be able to get more W/A out of the LM317 current source than a plain resistor, though it only matters if you need the extra resolution that the higher current provides.

[Anonymous No.1383358]

>>1382609
thanks matey!

[Anonymous No.1383367]

How can I check if my wall outlet is outputting exactly 230 volts without electrocuting myself?

[Anonymous No.1383368]

Do all common comparators require external pull-ups? Just thinking that it's a bit of a pain to add them every time if you'll pretty much always use a similar value.

[Anonymous No.1383369]

>>1383367
Exactly? Jam a non chinkshit DMM in there on AC voltage mode, highest range, pins in COM and V/Ω.

[Anonymous No.1383375]

>>1383368
Depends on your definition of common. Fast and very low power comparators often have push-pull outputs.

[Anonymous No.1383405]

How did Nikola Tesla's wireless energy transmission system work? Why does no one implement or use it?

[Anonymous No.1383413]

>>1383405
His short range power transfer methods used induction and air ionization. Short range inductive power transfer devices (wireless chargers) do exist. Power transfer via ionized air is impractical for most cases (too much voltage, too little current), but some electroshock concept weapons have been built around the idea.
His long range power transfer ideas were bullshit and no-one has implemented them, because they didn't work.

[Anonymous No.1383421]

>>1383413
>His long range power transfer ideas were bullshit and no-one has implemented them, because they didn't work.
Nu-uh you just need to make the earth resonate and you can use it to transfer energy.

[Joldberg No.1383432]

I’ve finished hooking up a led and a switch to the pin ports of a MSP430. I attached 4 mini projects. Do you guys recommend a mini project for my 5th to help learn or think weird?

[Anonymous No.1383433]

Is this a thread for scilab?

[Anonymous No.1383521]

Is this OK? Or is it retarded?, I'm trying to increase the current output of two identical boost converters.

Will try to match the voltage outputs as much as possible.

Not looking for efficiency (hence diodes instead of FETs).

[Anonymous No.1383522]

>>1383521
forgot pic

[Anonymous No.1383533]

>>1383432
Recommended projects for mcu beginner (from the top of my head, i learned a lot from these and are fun):

monitor input of one port as outputs of another port

traffic lights (you can start with 1 set then make a two traffic lights circuit)

multiplexing 7 segment displays (0 to 99 counter)

h bridge and pwm (vary the speed of a dc motor and change its direction)

line following robot (No PID just logic functions)

stepper motor control (you can use the same h bridge ic used in the line follower)

hobby servo control

lcd screen stuff ( just show some messages)

matrix keypad (show input in lcd)

houe alarm (lcd screen + keypad)

you can go back to the dc motor project and interface it with the lcd screen and keypad (visualize which way it's spinning and the duty cycle that you have inputted in keypad)

remote control robot using bluetooth module (use the same structure from line follower)

Read POT position using ADC

Read LM35 temperature sensor using ADC ( you'll need a dual op amp IC to amplify the signal) and visualize in LCD

You can do all of these withouth messing around with interrupts, only delays and basic i/o.

If you want to mess with interrupts then:

multiplex 7 segment using timer interrupts

read quad mode rotary encoder (make a tachometer using timer interrupts and lcd screen or 7 segment displays)

PID DC motor speed control (uses the rotary encoder circuit and h bridge)

PID DC motor position control (uses the rotary encoder circuit and h bridge)

PID line follower

Digital dimmer using TRIAC, LCD screen and keypad (control firing angle).

Read user input using interrupts on change

[Anonymous No.1383536]

>>1383521
Old-fashioned resistors would do better job, particularly if the regulators' output voltages remain close to each other.

[Anonymous No.1383537]

>>1383536
can you post a diagram

[Anonymous No.1383539]

>>1383537
Like yours, but use resistors instead of diodes.
Dimension the resistors so that the regulators output roughly the same (within 10%, for example) current at maximum load and maximum expected output voltage difference.

[Anonymous No.1383540]

>>1383539
thanks

[Anonymous No.1383579]

I bought an esp32 and it arrived today. What the fuck do I do with it now?

[Anonymous No.1383697]

>>1382609
thank you later

>>1383368
usually, because common use cases include a logic-high voltage that differs from Vcc, and wired-AND/wired-OR arrangements

>>1383579
why did you order it in the first place

[Anonymous No.1383700]

>>1383697
>why did you order it in the first place
because everyone was talking about it, i was already buying other stuff i actually need from ali and the thing was like 5€

[Anonymous No.1383701]

>>1383700
so exercise its facilities just to see that you can, then put it away until you figure out something to do with it

[Anonymous No.1383752]

>>1383320
i had a bit to drink when i posted that last night. you could just use an lm317.

[Anonymous No.1383761]

>>1383421
>make the earth resonate and you can use it to transfer energy
>inb4 schumann resonances

[Anonymous No.1383766]

>>1383697
>a logic-high voltage that differs from Vcc
Ahh, now that makes sense.

>>1383700
Fair enough. There's the /ohm/ project list on google images if you want ideas, and >>1383533's suggestions are all on-point for a beginner if you need practice. But in general if you're already messing about with electronics, chances are you can improve your projects with the addition of a microcontroller, or at least do things with it you couldn't do otherwise. ADCs and display driving being a main use, but also turning any digital logic ICs into adjustable software, not to mention interfacing with digital sensors and PCs. You've almost certainly already thought of a project that you'd need to use one for, like an LCR meter or chronograph.

[Anonymous No.1383840]

does ANYONE know of a 3-5hp single phase to single phase vfd? i cant find shit anywhere, every single one is single to 3 phase.

[Anonymous No.1383853]

>>1383840
You can just use a single phase of a 1-to-3-phase VFD, there shouldn't be a problem.

[Anonymous No.1383882]

>>1383853
you sure? most of what ive read says that it will fault out if there is a missing phase

[Anonymous No.1383885]

>>1382125
Are you sure that isn't a fluke?

[Anonymous No.1383906]

>>1383882
Oh, I guess it will have something in there to stop machines running if they've dropped a phase. You could go in there and spoof the "phase dropped" sensor, but it's a bit of a janky workaround.

[Anonymous No.1383909]

>>1383906
meh, ill just deal with it for now and look around for an affordable used 3 phase.

[Anonymous No.1383912]

I want to build a buck converter using this http://epc-co.com/epc/Products/eGaNFETsandICs/EPC2115.aspx but I can't find a suitable IC to control it, I just want a synchronous buck controller with simple PWM output able to operate in the MHz range but I can't find anything suitable that isn't an entire MCU which has to be programmed and takes up too much space.

[Anonymous No.1383915]

I want to split my existing 240v socket into 3 others, but I want to have each of them have their own switch so I can toggle them individually. The easiest and cheapest way I've come up with this is to use a small breaker box, which comes with the added benefit of having a pre breaker so if something does fault, it will trip the one in the sub box so it won't interrupt the other plugs and I wont have to go outside to reset it.
I've never done house wiring before so I used my world class paint skills to come up with pic related which is how I think it should be hooked up, is it right or did I just house fire myself?

>Why go through this shit instead of adding sockets to the main box
I don't want to have to fuck up my brand new freshly painted walls to add more outlets, this way it's just a few screws
>You do know that running a bunch of things on 1 socket will make it pop all the time right
I will very rarely have 2 of the loads going at once, all 3 probably never so overloading the host socket isn't a concern, either way any 2 of the loads I plan on hooking up won't even exceed the original breaker rating

[Anonymous No.1383924]

>>1383912
any particular reason that FET? most buck controllers will have their MOSFET drivers built-in. the ones in that device look like they'll only get in the way. also the common-source configuration doesn't look very good for a synchronous converter unless you really want to use two devices. cute af tho
would a 2.3mmx2.2mm WLCSP be too large? if not, you could use an "entire MCU" in the form of an LPC1101. the timers are as good as expected, ADC might be a little slow

[Anonymous No.1383928]

>>1383912
>buck converter
>using a dual fet with integrated lowside drivers
>must be easy
>must be tiny

Maybe you should pick a more suitable fet first.

[Anonymous No.1383929]

>>1383924
None of the devices with integrated fets can do what I need. I need to build a buck converter with a very wide input range for a motor controller. It doesn't have to be this exact mosfet but GaN or SiC are pretty much needed.

The problem with monolithic devices is you can get a 600V device but the Si mosfet device will have very high RDs on, at lower voltages it would have to be conducting almost the entire time and can't handle enough current. Secondly most of the monolithic options with high voltage fets have miserable switching speeds around 100khz, the size of the inductor becomes excessive. GaN and SiC options are ideal as they have low RDson that allows the buck converter to run at lower voltages while the high switching speeds mean only a small inductor is needed to convert high voltages. But finding an IC I can use without having to go through the trouble of firmware development is difficult.

[Anonymous No.1383947]

>>1383929
could you use something like the EPC2012C or EPC2019 with a standard off-the-shelf buck controller designed for high Vin-Vout differential? you'll still lose a good amount of board space from all the passives, so the microcontroller solution offers some advantages in compactness if its performance is satisfactory

[Anonymous No.1383958]

>>1383929
Could a flyback converter give you better specs?

[Anonymous No.1383964]

>>1383766
>>1383701
Imma build a digital guitar pedal connected to wifi that scrapes hashtags from twitter and changes the sound of the instrument depending on what is trending.

[Anonymous No.1383970]

>>1383964

were you looking for this thread?

>>1383587

[Anonymous No.1383976]

>>1383964
50 keks, friend. But it looks like hashtags can theoretically be the full 140 (139 + #) characters long. So how will you determine the sounds you get? I'm guessing more harmonics from more complex hashtags, so the number of letters in the hashtags will be proportional to the number of harmonics, though a rounded logarithmic relationship could also work to stop long hashtags from sounding like black midi.

Then the tone of the harmonics could be determined by the letters themselves, but whether you pick just alphanumeric or the full UTF-8 (minus special characters) will make a big difference. Presumably you'll want to limit yourself to harmonics that sound good, which will also limit you a bit. 32 bits of UTF8 would be problematic to sort, while 4 bits of alphanumeric would be attainable if you could convert the foreign characters into english ones.

You'll also need a DAC unless you want to try a D-class amp right out of the uC's PWM pins.

[Anonymous No.1383979]

>>1383970
I mean it's a cool concept. Imagine telling your audience that they can change your sound by tweeting, say "#bandname #keyword". That way your band trends and they get a kick out of it.

>>1383976
Thanks for the input! I literally just got the idea so I have done exactly 0 thinking.
You would also have some pots and switches on the pedal itself so maybe you could let the player select for example the key the song is in, and that would somehow ensure your audience doesn't fuck it up too much.
You could also have the hashtags be some preset value, like an enum, which would make things a lot easier...


I'm actually getting excited about this now.

[Anonymous No.1383981]

>>1383979
>select for example the key
Depends on what you want to change I guess, but with a microcontroller you could just put a digital filter and get only the fundamental frequency(s), and add different amplitudes of other harmonics/add new harmonics, which I think should be key-independent. Though doing this will potentially give the sound a lot of variance, a guitar could have the harmonics of a violin or even a saxophone if you alter it enough.

Adding key-dependant frequencies that vary less or not at all as a function of the tone being played might be a way for it to sound better, though I'd certainly experiment with both. Worst case this second method leaves you just with a hum or whine in the background.

So if I'm right we have the following input variables:
>key
>frequency, phase, and amplitude of single fundamental note
>frequency, phase, and amplitude of multiple fundamental tones within a chord
>frequency, phase, and amplitude of harmonics of fundamental(s)
>other instruments' inputs
>hashtag characters
>hashtag performance

And the following output variables:
>frequency, phase, and amplitude of new harmonics (including -1st harmonic, etc.)
>frequency, phase, and amplitude of new baseline frequencies

It's all quite a mouthful, though it does cover non-sinusoidal waveforms. Post how far you get in synthesising frequencies to match an instrument since it's something I'd like to do soon also. Phase should be relative to the respective fundamental for harmonics, but for the baseline tones it doesn't really matter.

[Anonymous No.1383984]

>>1382388
Just go all in

[Anonymous No.1384001]

>>1383947
>could you use something like the EPC2012C or EPC2019 with a standard off-the-shelf buck controller designed for high Vin-Vout differential? you'll still lose a good amount of board space from all the passives, so the microcontroller solution offers some advantages in compactness if its performance is satisfactory
I can't find much to choose from LTC has a 140V buck, if I could find a 40-200V 1A buck converter with a decent switching speeds I would just use it. The MCU route might be easier after all, anyone have any suggestions for cheap MCUs with buck converter reference software designs?

>>1383958
Not really then you have to deal with winding ratios and ordering transformers, which are typically bigger than inductors

[Anonymous No.1384002]

>>1383981
>Post how far you get
Don't hold your breath because I'm actually already working on something else right now and I'm not sure how long that'll take to complete. Uni exams are coming up too.
But i'm saving your comments so I'll post again about it when I do start with this. I've already contacted a friend who's really into music and hopefully he'll agree to work together.

[Anonymous No.1384003]

>>1384001
>which are typically bigger than inductors
Not for size efficiency, but for finding suitable FETs, assuming reverse voltage is somewhat of a limiting factor that you need to take into account.

[Anonymous No.1384004]

>searches for "nixie" on ali
>nothing but overpriced clocks and the odd IN-14
>searches for "magic eye" instead
>oh god no

[Anonymous No.1384005]

>>1384004
>took the bait
am i on some kind of list now?

[Anonymous No.1384042]

I bought a faulty PS2 for cheap and I'm trying to diagnose the source of the problem by using a multimeter.

I'm new to electronics. There is a 6.3A fuse here. How do I check if it is in good quality? It passed the continuity test on my multimeter. And it is reading 1.4ohms on the resistance test. But I can't seem to get anything on the DCV or ACV setting. Does that mean it is dead?

[Anonymous No.1384053]

>>1384042
First read: Michael Jay Geier, How to Diagnose & Fix Everything Electronic
For some components, generally you can't test them while they are in-circuit, because there are so many other paths for current to flow. Especially if some other component failed and short circuited.
You're not supposed to get significant voltage across the leads of a fuse, because V=IR and I is a few milliohms. But a zero voltage reading doesn't guarantee it's bad either.
A dc voltage across the fuse does however indicate the fuse has blown.
Probe ground with your negative, and then probe one or the other side of the fuse to even see if that section has a voltage.
The fuse is probably good.

[Anonymous No.1384068]

>>1384053
meant to say: But a zero voltage reading doesn't guarantee it's *good* either.

[Anonymous No.1384111]

>>1384053
When you say 'probe ground', that just means touch anything metallic on the board with the negative lead? I'm still getting no response.

[Anonymous No.1384122]

Also, the small clip holding the ribbon cable for the power switch broke off and I can't find it. Short of gluing, how do I keep this ribbon cable connected to the port? It has to be held in there currently or it easily slips out.

[Anonymous No.1384174]

I have a sprinkler system with 24VAC relays, the controller is dead. The controller had thyristors driving the relays.
Can i substitute a MAC4DHM thyristor with a C106M1G? Im not familiar with these, not sure what parameters should match.

[Anonymous No.1384183]

>>1384174
C106M1G is an SCR, while MAC4DHM is a TRIAC. Sometimes they're interchangeable, but more often not.
You pick a replacement which has the same or higher current rating, same or higher voltage rating and which is preferably in the same package (and has the same pinout). If it's a TRIAC and the original promised 4-quadrant triggering, your replacement should also support it. This isn't usually critical, though.
You can also google a cross-reference guide listing that particular component and see what it suggests.

[Anonymous No.1384190]

Hey /diy/, /g/ (mostly) here. I've got a shitty iron and have successfully fixed up some shit like some power supplies and swapped out some bad caps, but I can only really do the basics.

Now, here's the thing. I've got two identical shit-as-fuck netbooks that were a universal government handout, gibs in exchange for votes basically. Anyways, one of the laptops has a wrecked power delivery (ded ICs that I don't want to/can't because of skill with an iron fuck around with) and can't run off the power supply or charge batteries, but it will run off charged batteries. The other one has a general motherboard failure and it's ded as fuck, but it can still charge batteries.

I want to strip both down and frankenstein a Shadowrun-esque deck out of them. It'd be a fun project, exclusively for shits and giggles. I make a case out of scrap wood my old man has lying around, mount the motherboard inside, get two monitors mounted (one with a cheap LVDS-to-VGA chinkboard) on the lid, put some toggle latches on the lid so they don't fly open, screw a keyboard and trackball in there, a living shit ton of NICs and assorted I/O (mostly through USB converters), three point sling, vinyl wrap, gay-ass stickers, done. It honestly shouldn't be too hard even for a dumbass like me. I'm doing it strictly for fun, so please no bully.

The thing is, batteries. I could just put the second motherboard in there (it's gonna be big and have plenty of space left over, besides, they're tiny machines), wire that second motherboard strictly to charge up the battery and then solder a second set of wires to the working motherboard so it can run off them. That, I think, shouldn't be too much of a fire/explosion hazard, correct? But I've got two of the batteries, more or less identical ones (same spec, different OEM) and the working motherboard runs fine on either. Could I just... you know... wire those in parallel and do the same? Or would they blow up in my face when I try to charge them?

[Anonymous No.1384197]

>>1384183
Thanks. Will take this into consideration then.

[Anonymous No.1384217]

Is "Lessons In Electric Circuits" a good book for someone who knows absolutely nothing about electricity and wants to make cool shit? If not, are there any other introductory texts that would be useful? I tried reading the ones suggested in the OP but they didn't click with me. I've been reading Lessons In Electric Circuits recently as well (I'm up to the second chapter), but I don't want to invest time into something that'll end up being useless.

[Anonymous No.1384350]

>>1384217
i got started with "practical electronics for inventors". i think books are a terrible way to learn and serve best as a reference for things you know, but that one was enough to spark an interest and prompt my own learning.

[Anonymous No.1384356]

Hi!
I need to make a pcb where I can connect a raspberry pi zero w and a nodemcu with a DHT11 temperature sensor, does anyone have any idea how?

[Anonymous No.1384357]

>>1384356
to be clear, you just want your pcb to act as a backplane for these boards? i only know altium and wouldn't recommend it for this.

[Anonymous No.1384358]

>>1384356

[Anonymous No.1384360]

>>1384357
Yes, I really just need to feed the raspberry pi zero w and the nodemcu, also do the outputs for the dht11 sensor.
>>1384358
The desired size is like this box.

[Anonymous No.1384362]

>>1384357

[Anonymous No.1384364]

>>1384360
perfboard

>https://www.ebay.com/sch/items/?_nkw=pcb+perf+board&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&_fpos=&_fspt=1&_sadis=&LH_CAds=&rmvSB=true

[Anonymous No.1384389]

>>1384042
Well if you get the same resistance in both directions it's probably ok, but 1.4Ω sounds somewhat suspect. Nice looking PCB though.

>>1384122
I'd buy a new ribbon socket, if you'd be able to solder it.

>>1384190
You'd probably be better off making/buying a charge control PCB separately and wiring that directly up to the power rails of the working motherboard. But it's important to remove any interfering components still on the power supply section of the working board else they protest, like protection diodes and such. But a little solder wick and application of force may be able to get those working ICs off the bad board and vice versa, it's not something I'd discount just yet.

[Anonymous No.1384545]

>>1384360
the dude in >>1384364 is correct. if you know how to use perfboard, you can get "PCB perfboard" to make a permanent substitute for it.
no need to delve into the arcane world of PCB making.

[Anonymous No.1384548]

>>1384545
Are those plated thru-holes? Either way having some FR-4 perfboard would be nice, I keep having delamination issues with FR-2.

>no need to delve into the arcane world of PCB making
I hope you're not implying that making PCBs is a useless and archaic endeavour and that it's better substituted with perfboard. And with a good enough setup, even homemade PCBs can be as good as ones ordered from a factory, or at least without taking into account silkscreening and multilayer.

[Anonymous No.1384560]

>>1384548
"arcane" and "archaic" are quite far apart in meaning anon, I think he was just referring to it being way out of his real of knowledge, or seeming mystical

[Anonymous No.1384574]

>>1384001
is the Iq on that converter low enough to pre-regulate with a shunt regulator of some sort? if not, how about something like the LM5141 (2.2MHz)?

>>1384548
for just connecting so few leads, I personally don't see much point in etching and drilling a board. I'd probably go to the crimp box and pull out the Dupont kit

[Anonymous No.1384586]

>>1382125
That is impressive.

[Anonymous No.1384599]

Are those caps for noise filtration?

Looking at different models, some didn't have those caps in place.

[Anonymous No.1384602]

>>1384599
Yeah, they're for noise filtration. Some of the primary side (high voltage) square wave leaks through the transformer capacitance to the output and those capacitors bypass that noise.
They also provide some limited protection for the transformer and opto insulation.

[Anonymous No.1384648]

>>1384586
Only as far as you get them calibrated annually.

[Anonymous No.1384685]

>>1382125
i dont get it

[Anonymous No.1384691]

>>1384648
Good meters retain their calibration well, particularly if you treat them nicely. And those meters have been treated nicely.

[Anonymous No.1384733]

>>1384364
>>1384389
>>1384545
>>1384548
>>1384574
I could use a perfboard, but wouldn't that make the design bigger?

I'm leaving the design I made in Proteus and the NodeMCU pins look bad on it. (close together)

[Anonymous No.1384761]

Hello /ohm/, time for a stupid question. If I have a pcb with a bunch of components on it, all connected in a circuit, and I then take my multimeter and measure the resistance across one of the resistors on the pcb. Am I measuring the resistance of that resistor, or the resistance of the resistor in parallel with the rest of the circuit?

[Anonymous No.1384763]

>>1384761
Everything parallel. If you want to measure just the resistor, you could desolder one end.

[Anonymous No.1384766]

>chink sensor doesn't have a datasheet

[Anonymous No.1384788]

So what options are out there to provide remote communications, no more than a kilobyte per month. GSM and Iridium would be fine but i dont want to pay for it. The transmitter can get as far as 200-300kms.

[Anonymous No.1384791]

>>1383915
Your drawing is correct. Probably not up to code, but that's more of a guideline really. What really matters is that you make sure your workmanship is good. Make sure you use your equipment correctly, like make sure you use the right fittings for bringing conduits or cords into that box, strip the right lengths off the wires, if you use wire nuts use them properly, make sure your connections are tight.
note on sizing breakers:
Breakers are sized to protect the wiring, not just for what load you expect. If you're really putting 30 amp breakers in that box, make sure you use big enough wire (10 gauge). If you don't really need that much current, you can downsize the wire, but make sure you downsize the breakers too.

[Anonymous No.1384804]

>>1384788
Assuming you live in a country with sufficient coverage, Sigfox would fit the bill. Except that it isn't free either.
I would just go with the cheapest GSM, though.

[Anonymous No.1385039]

>>1384791
That's good to hear, and yes I plan on making sure I do it perfectly and pretty-ly so I don't burn my house down nor have an ugly eyesore to look at every day. The 30 as just a label really, the loads will likely be 20, 20, 15 but I'll probably use 10 gauge on all 3 just for protection and buy once cry once fuck with it once

[Anonymous No.1385054]

>>1385039
buy once cry once, but don't cry harder than you need to. 10 gauge wire is more expensive and harder to work with, don't use it unless you really need that kind of power. 30 amps at 240 volts is a lot. what are you running, machine tools?

[Anonymous No.1385063]

>>1385054
3.3kw air compressor, 2.4kw lathe, planning on a mill so that's another 2-3kw

[Anonymous No.1385068]

>>1385054
Plus im also expecting to upgrade to 5hp 3 phase motors on the lathe and theoretical mill, so that plus the vfd overhead bumps it up a little bit, and the air compressor motor pulls almost 30 amps on startup too.

[Anonymous No.1385069]

>>1384766
Wow that sucks. It's probably a renamed clone of something that does have a datasheet though, so browse the usual suspects in search for other names.

[Anonymous No.1385080]

Also please recommend guides on analog electronics and/or the myriad of 12v modules and boards china is cranking out.

I've got some CE030 timer modules and the trigger (marked INI) resets to the start of the count when the circuit is made but doesn't hold it for as long as the circuit is made. I need a way to automatically pulse a continuous 12v DC signal to trick the module.

[Anonymous No.1385085]

>>1385080
>12v modules and boards
>CE030
ew just use a 555

[Anonymous No.1385092]

>>1385085
meh, I used a pair of these CE030 boards building an auto-feed case neck annealer for reloading rifle brass because they're noob friendly and versatile.

I'm thinking I need a low frequency square wave pulse generator. Could the same effect be created through a mashup of loose caps, diodes, resistors and relays?

[Anonymous No.1385094]

>>1385092
there are myriad cookbooks devoted to the 555 chock-full of timer applications of any sort, both paper and online. the astable multivibrator called for in >>1385080 is usually among the first of the recipes. joe bob sez check 'em out

[Anonymous No.1385095]

>>1385092
>loose caps, diodes, resistors and relays
Possibly, but it would be wasteful to run the relays constantly like that. Transistors would be a better bet, if you've a couple of BJTs lying about there you could make a very simple multivibrator.

[Anonymous No.1385132]

>>1382101
Wondering if it's a thing to wire a small residential house using DC, such as LED lights, some fans, even the fridge (I found one that seems to fit the bill). This is for an off-grid home I'm building this fall and I will be using solar for my electrical needs. If it's too much to ask really, then I suppose I'll just keep going with the current standard (haha, see wut I did thar?). I'm no electrician so I worry about finding someone who won't think I'm crazy if I ask them to wire DC. So yeah I'm not really a DIY'r but not sure where else to ask (not /sci/ fukc those guys).

The house is small and the only appliance I can't find a DC, gas, or "other" version of is a washing machine. I'm using clever passive heating/cooling design, high efficiency woodstove for winter heating, clothesline for drying, and gas for cooking and heating water. I would still have an inverter for AC wall sockets since I believe that it is code to have wall sockets every 12 feet. You may notice I'm a complete novice here so please be kind. Constructive criticism only pls.

[Anonymous No.1385147]

>>1385132
There's nothing particularly wrong with the idea, in fact if the voltage is high enough you'll be able to run all your normal power supplies off it. Though I wouldn't run DC to your normal wall sockets as a safety measure. You'll need switches and breakers specifically made for use with DC, and chances are you'll want significantly thicker copper. You also probably won't be able to have a microwave without an inverter. What voltage would you go for?

Washing machines typically use an induction motor, which requires AC power to function. But chances are (with a little fabrication) you'll be able to wire a big DC motor in there instead. If you can find one with the same RPM and the same mountings then excellent, but it probably won't be that easy. I wouldn't know, I've never taken apart a washing machine.

[Anonymous No.1385152]

>>1385132
I've heard of standards for extra-low-voltage residential wiring, but I haven't seen it anywhere. the main problem is E=IR so you need much larger wires and/or shorter runs to maintain a certain percent of energy loss in the wire
which is more available to you, mains voltage or 12Vdc? step-up converters are less efficient than step-down converters and neither is 100% efficient
that said, my desk/workbench are lit and wired with primarily 12Vdc provided by a single open-frame switching power supply in a wiring closet. I'm considering doing my whole living room/kitchen area in 12Vdc, in fact, because flickering lamps suck
>washing machine
here you go

[Anonymous No.1385156]

>>1385132
There is no building or electrical code outside of city limits.
You can get a propane fridge. Skylights eliminate most need for indoor lighting and gas mantle lamps work fine at night. Granny raised 8 kids on a farm with nothing but a wringer washer and clothesline. It'd be no problem converting one to a DC motor. You could also look into the countertop hand power models. Fill them up, put on the lid, pressurize it. spin it for a while and drain.

[Anonymous No.1385160]

>>1385147
>What voltage would you go for?
No idea. I live in a RV now and it uses automotive lights which run 12 VDC I think. I haven't even used a microwave in years. I don't mind using AC for the outlets and I know I have to use thicker copper. Actually that's my main worry if it will be worth it. It's a roughly square 1200 sqft home, so 50 ft max length from one corner to the opposite corner. And the switches and breakers... I think I've seen some that work with DC.

>>1385152
lol got u 1 better
The problem is I don't feel like wiring the whole house myself and finding an electrician who's done this before.

>>1385156
I'm sure you're right but this is the future. Actually there are DC fridges. But yeah, I'm not sure my house will have much resale value without electric lighting and appliances.

[Anonymous No.1385163]

>>1385160
I'd use 24V if not 48V, 12V will require far too thick wires to be economical I imagine. But whether you can set up your solar setup to produce those voltages is probably your main concern.

[Anonymous No.1385166]

>>1385163
Yeah probably 24V then. Think I could find someone who would wire it all together for me?

[Anonymous No.1385169]

>>1385166
sparkys will do anything (safe and legal) for a buck
it wouldn't hurt to call around and see who takes you seriously. try to have your appliances/lighting systems roughly planned out and components identified before you do
>washing exerbike
noice, kinda want one

[Anonymous No.1385172]

>>1385163
Well wait, I think solar fed batteries normally use 12VDC. You think the wires will be too thick to run appliances straight from the batteries? Would there be other problems potentially? Living in this RV, I notice the lights dim as you turn more things on.

[Anonymous No.1385177]

>>1385169
>sparkys will do anything (safe and legal) for a buck
That's cool and gives me a little hope anyways. In all likelihood I'll end up caving to normalcy but right now the dream is self-sufficiency and efficiency.

[Anonymous No.1385182]

>>1385160
>>1385163
>>1385166
I've seen big RVs and even cabins that were all wired for 12V.
Bigger yachts are 24V but it's a bit harder to get 24V equipment. Just some food for thought.
If you're curious about resale value, look how many off-grid homes you can see in the realtor listings. I've seen plenty in my province that do sell, so there is some demand for it. I know people who live off grid. Some people just want that lifestyle.
As for electricians, just call around... I don't even think you need to have an electrician to pull low voltage stuff, a data technician can pull that unless you're in a cucked state like california or something.

[Anonymous No.1385231]

This a good design for a rail splitter that can source a relatively large amount of current (more than the 10-20mA of the typical buffered virtual ground divider)?

Simulation shows it can pull about 273mA from V+ to ground before becoming unbalanced. V- to ground is a bit worse at 200mA but still respectable. Would using FETs for the power amplifier improve it?

[Anonymous No.1385237]

>>1385231
notice that Q1 and Q2's current handling capability is limited by R3 and R4. try replacing D1 and D2 with resistors (56 ohm?) and see if you get more drive
second thing would be to choose better transistors, with dc current gain that doesn't fall off so quickly at loads of interest
tbqh if you're placing power loads on your virtual ground *reference*, you're doing it wrong

[Anonymous No.1385239]

>>1385237
I'm not putting any really crazy loads on it but I might be planning to drive a rather large amount of analog circuitry so each rail being able to source 100mA or so and still maintain Vcc/2 would be nice. It's this or flyback converter with grounded center tapped transformer for the split rail. The nice thing about that is I can get +/-12 V instead of +/-6 but it's more complex to design and it's a pain to wind a custom center tapped transformer.

I just want the thing to be linear, balanced, and not oscillate a lot if loaded capacatively.

[Anonymous No.1385243]

>>1385239
pro tip from the ghost of Bob Pease: the best way to evaluate that is to breadboard it, hook it to a storage o-scope or other high-speed sampling device, and literally short the output terminals roughly with a crow bar or screwdriver to check for robustness and ringing. if concerned about ringing, overdamp the hell out of it, but if start-up behavior looks good, you probably won't have much of a problem
the open loop gain of the op-amp will fix up almost any error you could do in the power stage (including tying the output of the op amp directly to the base of the bottom transistor). you'll probably want an op amp with rail-to-rail output if you're going to push it to extremes, or just leave that 2.5x headroom and upgrade the transistors or lower R3/R4 if it becomes a problem
also, in the real world, you're going to want to thermally bond those diodes fo their respective transistors to keep the quiescent current consumption somewhat stable

[Anonymous No.1385245]

>>1384574
>is the Iq on that converter low enough to pre-regulate with a shunt regulator of some sort? if not, how about something like the LM5141 (2.2MHz)?
Won't using shunts or LDOs to supply them just lead to other inputs being killed by higher voltages?

[Anonymous No.1385252]

>>1385245
I don't think so but I'm not sure. Vcc and Vccx are regulated internally from Vin. the high-side FET's source is toward the low side so Vgs won't be very high, but you should make sure the high-side FET has a suitable Vds(max). now that you mention it, I'm a bit concerned about SW, but Lout would protect the other three inputs as long as the high-side FET didn't blow short
(all assuming you are designing with the non-drivered GaN FETs I suggested)

[Anonymous No.1385267]

>>1385252
Maybe I could use a voltage divider + zenner on SW, if I'm bypassing the internal fet drivers it's only used to control dead time and prevent overlap.

[Anonymous No.1385269]

>>1385267
it looks like it's also used to pull HOL to SW. as long as you're still within the Vgs(max) spec when that kicks on, you should be alright

[Anonymous No.1385530]

my latest project is a humidity/temperature sensor. i'm using a pic16f54 because it's really dumb so it fits the through hole vibe. i added an IR sensor that, based on my math, should be able to detect my hand at 3" to wake the display. i'm 75% sure it'll work.

[Anonymous No.1385631]

>>1385530
Shouldn't you breadboard that IR sensor?

[Anonymous No.1385634]

>>1385631
yes but i'm not going to

[Anonymous No.1385637]

>>1385634
Flying by the seat of your pants, that's also respectable.

[Anonymous No.1385641]

>>1385637
the code displays temperature for 4s and then humidity for 4s after a 12-16kHz signal is detected for 100ms. if the IR circuit can't be made to work i'll just leave it cycling between T and H every 4s without blanking the display.

[Anonymous No.1385648]

>>1385641
I might borrow that IR sensor design. HDAT will constantly be oscillated at that ~12kHz, right?

[Anonymous No.1385658]

>>1385648
the humidity sensor (HDAT source) is capacitive so it ranges from 12 to 16kHz. IRDA is all >30kHz according to google.

the human hand has a reflectivity of 0.9% so i'm looking at 20nAC through the photodiode at 76mm. easily swamped. my application doesn't care about occasional interference from legitimate signals and i'm relying on the RC and 10 turn trimpot to keep out any noise.

[Anonymous No.1385676]

>>1385658
>20nA
And that takes into account the radiant intensity from the LED and subsequently that reflected from your hand onto the sensor? Doesn't sound impossible, I was running some very low light level tests with a photodiode and certainly got some visible results.

[Anonymous No.1385710]

>tfw you leave the arduino environment to try and program the esp32 with their development framework
holy mackerel, it's like leaving the calm waters of the port to venture out into the stormy seas.
H-Hold me /ohm/...

[Anonymous No.1385712]

>>1385710
"development framework" is probably your biggest source of problems. i think they're designed to be as miserable as possible as a sick form of job security.

[Anonymous No.1385791]

>>1385710
consider NodeMCU as a reasonable advanced rigging lesson

[Anonymous No.1385802]

What should the magnitude response of a matched load look like? Teacher gave us data to plot in AWR software, and when i plot this on a smith chart it's a matched load, but the magnitude response (pic related) doesn't really make sense to me.

[Anonymous No.1385901]

If I wanted to make a tiny portable computer (rasp-pi-0 based or something similar) what sort of mouse could I use? I'm looking for something akin to a Trackpoint mouse or a hat switch, but I can't find either, all I can find are Xbox thumb sticks, which would be fine if there was a good way to turn that into a mouse input, but it's analog so would require an ADC else I'd be dealing with the lack of detent.

Is the only way to put 4 (or 8) tactile switches in a cross pattern and have some connecting plate atop them all?

[Anonymous No.1385904]

>>1385901
>hat switch
you mean a five-directional switch?
>not using a touch screen
hmmmmm

[Anonymous No.1385912]

>>1385904
>five-directional switch
Ah, because I was searching for four-directional due to forgetting about the integrated pushbutton. Well that makes left-click easy to implement.

I'd use a touchscreen if the software I plan on using would work well with it, but I'll barely be using the mouse and will probably just use the arrow keys for the most part, for which I could use another of those switches. Though now that I look at it all the screens I was considering are touch-screens anyway, but I can still use the thing for the arrow keys.

[Anonymous No.1385914]

>>1385912
you might also consider these little guys for mouse or other buttons
https://www.aliexpress.com/item/toucha-toucha-toucha-touch-me/32657134552.html

[Anonymous No.1385919]

>>1385914
I guess it wouldn't be too difficult to make a capacitive pad matrix on a PCB and have a bootleg trackpad that way...

[Anonymous No.1385992]

Does anyone know what the larger chip in the picture is? It’s some sort of storage but I can’t find the actual part used.

[Anonymous No.1385995]

>>1385992
fixed

[Anonymous No.1385997]

>>1385992
what makes you even think it's standard? for all you or we know it could be a large ROM and a microcontroller all in one

[Anonymous No.1386010]

>>1385997
With that many unused pins it probably is.

[Anonymous No.1386068]

>>1385992
The big chip is a mask ROM containing the game. The little chip is an EEPROM or FRAM containing save game data.

[Anonymous No.1386096]

>>1386068
Yeah I was able to find the smaller chip earlier it is some flash memory but I wanted to see if there was a standard ROM chip that Nintendo used in their flash cards. In any case thanks for answering

[Anonymous No.1386103]

>>1386096
Does searching for what's written on the IC not work? Octopart and such have a fairly extensive library of ICs.

[Anonymous No.1386120]

>>1382101
hey guys i really want to make some ricer lights for my car out of leds, how would i go about setting up animations that respond to inputs like turning on the indicators or braking?

im a complete noob at this shit i only know absolute basics.

could it be done with a rasberry pie?

[Anonymous No.1386126]

>>1386120
a microcontroller like the arduino is enough for this. You just have to plug your LED strips into the arduino outputs and whatever signal you want to detect (indicators or braking) to the inputs.
However, I wouldn't know where to find the connections for these electronics within a car, and also you will have to check what voltage they use. If it's too high (>5-6V DC IIRC) you will have to use a couple of resistors to make a voltage divider. I think most electronics on cars work at 12V so I guess you will have to do this.

[Anonymous No.1386128]

>>1386126
would the arduino be able to control the colours and brightnesses of the leds too?

[Anonymous No.1386133]

>>1386128
Yes, as long as you buy RGB LED strips. But because the pins of the arduino can only output 50mA of current max, you will have to instead use it to drive a mosfet (a transistor), which will act like a switch to let current from your battery into the LEDs.
If you want to automatically vary the brightness you will have to use an analog output I think. This will allow you to open the 'switch' (the mosfet) more (or less), changing the amount of current flowing to the LEDs. Alternatively, you could control the brightness manually if you instead connect a variable resistor in series with your LEDs and battery. That way by turning the knob you would increase/decrease the resistance in the circuit therefore decreasing/increasing the brightness.

[Anonymous No.1386135]

>>1386128
>>1386133
Here, have a look at this website: https://learn.adafruit.com/rgb-led-strips/usage

[Anonymous No.1386138]

>>1386133
yeah feeding current from the batteries is what i was thinking

also i was planning to have a whole bunch of individual rgb leds rather than strips, would it still work with those?

>>1386135
thanks my man

[Anonymous No.1386144]

>>1386138
>also i was planning to have a whole bunch of individual rgb leds rather than strips, would it still work with those?
Yeah, no reason why it wouldn't. Only thing I'm not so sure which would be the best way to wire them together, parallel or series. However, is there any particular reason why you want to go with individual rgb LEDs? I think strips would save you a lot of wiring and headaches.

[Anonymous No.1386151]

>>1386144
i want to have them in a specific pattern and i want to be able to control the colour and brightness of each individual led.

i might be a bit in over my head here so maybe i will start out doing this in a simpler way but im really just trying to see how feasible my end goal is

[Anonymous No.1386176]

>>1386151
I see. Then maybe you don't even need mosfets... It will depend on the specs of your LEDs though. Do you already know which ones you want to buy? LEDs always need a certain voltage across them, but the current passing through them is what defines their brightness. The most commonly used LEDs for hobby electronics are low power so they can be driven straight from the arduino and they are bright enough. For ricing cars I dunno, but if the current they require is higher than 50mA you will have to go with a mosfet and get the juice from your battery.

If you want to control each LED individually you will be limited by the number of pins on the arduino, but I think there are ways to get around that, like multiplexing. I've never done it though so I'm not really familiar with it.

[Anonymous No.1386180]

>>1386176
they shouldnt need to be too bright these are only the rear lights, i guess i wont need mosfets then

thanks for the info my man

[Anonymous No.1386191]

>>1386180
I mean if they need to be seen by other cars in broad daylight I suspect they might be too strong for an arduino by itself. I'm not sure though. I recommend looking more into this, so check datasheets, ask friends and do some tests before buying bulk.
I'd also recommend looking up some tutorials, electronics basics but also car ricing, more specifically.

Godspeed anon. Don't forget to post progress/results.

[Anonymous No.1386224]

>>1386180
bear in mind that a bright indoors led is a dim outdoors led

[Anonymous No.1386347]

>>1386126
>a voltage divider
Use a linear regulator like a 7805, if not a 12V-5V buck converter.

>>1386151
>control the colour and brightness of each individual led
This will require some sort of massive multiplexer and makes this project much more complicated. And I think you'd need to drive the thing at a frequency equal to the PWM frequency multiplied by the number of individual LEDs (no or RGB LEDs *3), which is a somewhat big number, enough so to consider multiple multiplexers. Having some symmetry to the whole system would help cut down on this frequency, such as the same brightness of LED every 4 LEDs like a chaser circuit.

By multiplexer I mean the 74HC595 latching SIPO shift register, there might be better options.

[Anonymous No.1386352]

>>1386347
>>a voltage divider
>Use a linear regulator like a 7805, if not a 12V-5V buck converter.
Why do you suggest those instead?

[Anonymous No.1386414]

Got my plaster today! So I can build the LED starts. Seems pretty straight forward. Now I just have to wait for the lenses, which should be here in a couple of days, and then get some aluminum to mount the LEDs to and set all that shit up. Getting excited for this project again but still going to be a few days before I actually start putting everything together.

[Anonymous No.1386421]

I DID IT

[Anonymous No.1386428]

>>1386352
Because the output of a voltage divider is highly dependant on the current you pull with it. Unless you use very low resistances (R_divider << R_load) for your divider and waste a bunch of power, that is. Even a zener will probably be fine, provided you're not pulling an amp or two.

[Anonymous No.1386436]

>>1386421
>buh-buh-buh B PRUS??

[Anonymous No.1386452]

>>1386436
no prus mynus

[Anonymous No.1386501]

>>1386347
there do exist shift registers with PWM, designed mostly for signage applications. TI's TLC5940 and TLC5947 are decent options
>a power regulator
>for signal voltage level translation
>into a high-impedance input
no, seriously, you gotta stop

[Anonymous No.1386566]

>>1386096
It's using a non standard 8 bit bidirectional parallel interface with encryption, so probably a custom chip, or possibly a standard ROM + controller combined into a single package to avoid people trying to dump the ROM by sniffing the bus inbetween.

[Anonymous No.1386568]

>>1386103
First line is the nintendo part number, NTR-AMCE is Mario Kart DS (NTR being Nitro, the DS's original codename) Second line suggests a standardised series of chips, 256 being size in Mbits, but no hits on parts or datasheet sites.Third line is date code + presumably manufacture site/batch.

[Anonymous No.1386570]

>>1386428
Rload of the input pin of a micro is consistent and very high, just a resistive divider is fine. Hell, doesn't even need to be a divider, just a big resistor in series and let the internal diode of the micro clamp the voltage can be fine.

[Anonymous No.1386575]

>>1386414
nice phone case you got there
one of the nice features about STARS-922 is that it's silicone-like and therefore flexible, so can be removed with just a bit of force

[Anonymous No.1386617]

>>1386501
>for signal voltage level translation
I thought he was talking about the power supply for the arduino or whatever he was using. He referred to:
>the connections for these electronics within a car,
so since the existing headlights would be relay driven there wouldn't be any need for signal level translations, but I may be wrong. Wanting to remove the relay all-together is a good idea if you care about the Q-current I guess, but it means it will require more work to convert it back again. In the circumstance he wants to have proper headlights running and some cheapy LEDs in the vicinity then it would be a wise idea to keep the existing relay and run a divider off that (with a pullup I guess) but this isn't needed for the rear lights at all, which is mainly what I was thinking about.

Could easily be wrong about that first assumption of course, it just made sense at the time.

[Anonymous No.1386753]

>>1386617
my impression of his plan is that he wants to monitor body controls/switches with a lolduino and trigger light effects when changed. so indeed he's going to want something robust to the famously noisy, spiky automotive power supply to power the lolduino and the LEDs, but not to sense contact closures

[Anonymous No.1386757]

>>1383885
underrated post

[Anonymous No.1386758]

How small can you make an FM radio? This RDA5807M looks pretty damn good and it's damn cheap (I assume the headphones here act as the antenna, which is neat). But it does require a connected MCU (I think) and is tuned externally. The KT0913 looks even better since it has an optional pot for tuning(?), but it shows those I2C pins going to a micro in an example circuit. What are these microcontrollers used for? I guess I can just slap an ATTiny there and an encoder if I just need it for selection and a few buttons, but it really seems like something that could easily be integrated into the IC itself.

Looks like these things pull about 20mA at 2-3V, and I'll add 50mA extra for driving the headphones themselves. This gives about 0.18W, or about 7 hours on a AAA-size Li-ion. 0.8W is trivial to get with solar, if you're so inclined.

[Anonymous No.1386761]

>>1386753
>he's going to want something robust to the famously noisy, spiky automotive power supply to power the lolduino

I've had a home made AVR board in my 84 Ford piece of shit truck for years, to monitor temperatures and such, and it works fine with an ordinary 7805 regulator and a 2200 uF cap; not sure if that meets your standards of "robust", but then you're quite the electronics snob so who knows.

[Anonymous No.1386780]

>>1386758
>what are these microcontrollers used for
reading back RDS data, setting/getting volume/bass/treble, etc.
>could be integrated
b-but how are you going to differentiate your product from anyone else's?
Silicon Labs makes several FM radio chips, they're worth a look

>>1386761
having merely stumbled across a few dc-dc converter datasheets in the process of other searches, I can only attest that it doesn't meet the industry's standard of "robust", i.e. being able to withstand spikes of 42Vdc or so

[Anonymous No.1386828]

>>1386761
it's not snobbery, friend: http://www.eenewsautomotive.com/design-center/robust-automotive-supply-protection-iso-7637-2-and-iso-16750-2-compliance
but if your board survived for years, then great. but the ISO specifications were written because of how much electronics got fried due to power supply problems in vehicles.

[Anonymous No.1386836]

>>1386828
>but if your board survived for years, then great.
It is reasonable to expect any single not-totally-fragile device to work just fine. The shittiness of car power becomes a problem when you try to mass-produce stuff and even one fried device per 100 sold hurts your profits.

[Anonymous No.1386848]

>>1386836
yes, I meant "great for him", and yes it's statistically insignificant.

[Anonymous No.1386889]

>RASPBERRY PI NOOB QUESTION

I know my way around linux enough to get by, but decided to also expand on analog knowledge.

So I bought an I2C 16x2 Display and tried connecting it.

From review and Q&A I understand that the lcd has the address 0x27, but the i2c backpack has none.

product link: https://www.amazon.de/gp/product/B01N3B8JMN/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

I connected everything in multiple configurations but neither the display nor the i2c PWR LED light up. I tried with both the LED jumper connected and disconnected.

I tried connecting directly to 5V, directly to 3V3, and 5V via a level converter. And still neither the LCD nor the backled light up.

Anyone have any experience with such Pi+LCD configs? Is there anything on the software side that needs enabling?
I know my way around linux enough to get by, but decided to also expand on analog knowledge.

So I bought an I2C 16x2 Display and tried connecting it.

From review and Q&A I understand that the lcd has the address 0x27, but the i2c backpack has none.

product link: https://www.amazon.de/gp/product/B01N3B8JMN/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

I connected everything in multiple configurations but neither the display nor the i2c PWR LED light up. I tried with both the LED jumper connected and disconnected.

I tried connecting directly to 5V, directly to 3V3, and 5V via a level converter. And still neither the LCD nor the backled light up.

Anyone have any experience with such Pi+LCD configs? Is there anything on the software side that needs enabling?

[Anonymous No.1386891]

>>1386889
yes, there is everything on the software side that needs enabling. it doesn't just magically pop up as a tty
http://www.circuitbasics.com/raspberry-pi-i2c-lcd-set-up-and-programming/

[Anonymous No.1386980]

>>1386891
Did all that, yup. Last time I tried plugging it in to 5V without a level converter and it turned hot pretty quick so I disconnected it. Damn hardware

[Anonymous No.1386991]

>>1386980
you mighta dun goofed and burnt out your backpack or I2C port

[Anonymous No.1386996]

>>1386991
fugg. I ordered another one. How do I prevent future fuckups?

I know the pi's ports are pretty resilient, I'm counting on that

[Anonymous No.1387006]

>>1386996
Read the datasheets.

[Anonymous No.1387039]

>>1386780
>Silicon Labs makes several FM radio chips, they're worth a look
Thanks for that suggestion, looks as if the Si4825-A10 doesn't require anything resembling a microcontroller, though tuning requires a pot and is mono audio only. If anyone has seen pic related for less than $35 online it would be greatly appreciated, since a multi turn should allow me enough frequency control for an FM radio. I can only find them on Alibaba and Global Sources, wholesale sites.

>>1386889
>I2C 16x2 Display
>analog
lel

[Anonymous No.1387124]

>>1387039
are you looking for that specific brand? 10-20 turn trimpots are on digi for $2

[Anonymous No.1387281]

>>1387124
No I need one with a long knob so you can turn it with your fingers. Those ones are 8mm long.

But I just thought that if you went this route I wouldn't have an easy frequency readout, so using a tiny microcontroller and some up/down buttons is probably a better way to go.

[Anonymous No.1387315]

>>1387039
Such pots are not usable for tuning, way too much play where the slider doesn't move. Look for DSPM2 which comes with a real tuning capacitor. https://www.aliexpress.com/item/DIY-FM-Stereo-TV-Sound-MW-SW-Reception-DSP-Full-Band-Radio/32335800704.html

[Anonymous No.1387348]

>>1387281
and that's why they use microcontrollers :^)
>analog
lel

>>1386996
yes, RTFdatasheet

[Anonymous No.1387403]

>>1387281
But now I'm trying to imagine the smallest display. 8x16 will work for 3 digits + 1 decimal point, but imaginably there isn't much market for such small displays. On the other hand, the 128x32 displays made for arduino are cheap, thin, and only take 2 MCU pins, so I could just mount it to the reverse of the main PCB, and move all the components on its breakout board over as well.

With a display like that I could add a rudimentary VU meter or signal:noise readout, provided there's enough memory in the MCU.

>>1387348
>and that's why they use microcontrollers
Pretty much.

I'll buy a selection of breadboard-able parts and prototype it sometime soon to see how feasible it will be. If I go for bottom-barrel parts it will be around about $10. I hope the ICs can swap between mono and stereo FM though, since I get worse S/N when listening in stereo mode.

[Anonymous No.1387454]

>>1386996
>I know the pi's ports are pretty resilient
they aren't

[Anonymous No.1387516]

>>1387403
if the chip you choose has RDS, you could also display that
also there's usually a forced mono bit somewhere you can set/clear

[Anonymous No.1387535]

Startin senior year this Fall and need to do a 2 semester final project (EE undergrad), any ideas? I have a few but may save them for my own free time later on as they could be too difficult. I dont have many other ideas as I plan to be in a different field for grad school anyways.

[Anonymous No.1387544]

>>1387535

make an orgasmatron: electro-magnetic stimulation of the brain to produce orgasms.

become the world's first trillionaire.

[Anonymous No.1387547]

>>1387544
I have to live with my parents for another year after I graduate so no thank you

[Anonymous No.1387550]

>>1387547
>lets the mere fact that he's living with his parents stand in the way of becoming a trillionaire
wew lad

[Anonymous No.1387582]

>>1384685
models from 3 decades all measure accurately

[Anonymous No.1387856]

Can anyone tell me how (or otherwise direct me somewhere) to crimp one of these coax connectors? The centre pin is hollow as if it should be crimped onto the coax's copper but it's a tight fit with the female end so crimping it would probably render it unable to fit. Soldering being the alternative, provided solder will wet to it. The female version of the same socket has a screw to hold this centre conductor in place. The part with 4 leaves/petals is also an unknown, the shielding could go over or under it. Putting the shielding over the 4-leaf pinches it between the threaded ring that clamps over it, which would probably give it a strong electrical connection but I'm worried that it might cause the shielding to tear.

[Anonymous No.1387858]

>>1387856
I fucking suck.

[Anonymous No.1387904]

>>1387858
Does the centre pin have a hole (arrow)? If so that's the place to solder the centre conductor of the coax to the pin. The braid goes over the insulator and is then inside the 4 leaves.

[Anonymous No.1387930]

>>1387858
Pic related, also >>1387904, you may need a soldering iron

[Anonymous No.1387932]

My textbook says an npn BJT is in the active region if the base-emitter junction is forward biased and the base-collector junction is reverse biased. In my understanding, that implies Vc > Vb > Ve.
It also says that Vbe ~= 0.7 V and Vce > 0.2 V satisfies the active-region conditions. But Ve = 0V, Vb = 0.7 V and Vc = 0.4 V would mean both juntions are forward biased which contradicts the first statement. Am I retarded or is my textbook shite?

[Anonymous No.1387944]

>>1387904
>>1387930
Ah right, will try now. Mine does have the hole.

[Anonymous No.1387952]

>>1387932
Are you sure it's referring to Vce and not Vbc?

[Anonymous No.1387954]

>>1387952
not that I can see

[Anonymous No.1387964]

>>1387944
Well it looks like shit, but I hope it works. It's an antenna swapper with a DPDT switch that grounds the unused antenna so it doesn't couple capacitively though the switch. There's tin foil under the tape connected to ground, and another layer of tape beneath that for insulation.

[Anonymous No.1387965]

>>1387932
it's saying that none of this neat characterization applies if Vce ~< 0.2V, see graph at top of right-hand page

[Anonymous No.1387966]

>>1387964
Oh, it still couples capacitively in the centre-off position.

[Anonymous No.1387970]

>>1387965
I get that. Still, if Ve = 0V, Vb = 0.7 V and Vc = 0.4 V, is the transistor in saturation or the active region?

[Anonymous No.1387974]

>>1387970
base(p)-collector(n) would be forward biased so saturation

[Anonymous No.1387986]

>>1387974
But that contradicts what it says in the box on the right hand page, and figure 13.16a. I think I expressed this apparent contradiction clearly enough in my first post. Are you one of those Pajeets who post answers on stackoverflow without having read the question?

[Anonymous No.1387992]

>>1387986
Not him, but I don't think Vce is usually as low as 0.2V, at least I always assume it's 0.7V in the linear region. Since less current is going through the base than the collector, and modelling c-e and b-e as diodes with about the same forward voltage, you'd get the b-c diode reverse biased since the base will be at a lower potential than the collector.

[Anonymous No.1387995]

>>1387992
Well in the linear region the voltage is indefinite, but I mean more like in emitter-resistor and base-collector connected arrangements.

[Anonymous No.1388138]

Might get a Chinese Mitsubishi PLC clone.

No real projects in mind though.

[Anonymous No.1388195]

>>1387964
that looks like shit. I love it.

[Anonymous No.1388230]

Got a handful of questions for y'all.

Are there any good cheap electronics tools I should snag from /csg/ type sites like AliExpress? I have the basics, but things like those little plastic things to bend wires at specific lengths, SMD ruler to check which size a component is, etc.

Is there a preferred brand for 898D hot air station clones? I've got a solder station, so I'm getting a separate hot air station instead of an all-in-one.

Is there a best place to order those Wen Tai SMD storage boxes? I want to find some sizes #2-#4 that are a better deal than getting a bunch of #1's with it so I can use them for non-/ohm/ storage.

I have an SSD with a physically damaged SATA plug. I want to just solder on a fresh one, but I'm having trouble finding the part; I think I'm probably not searching the correct term. What should I be looking for?

Likewise, I want to get just the circuit from inside these things. You can find little 7-segment LED displays that measure voltage and amperage all day long, but these are the cheapest thing I can find to measure resistance. I know they aren't better than just using my DMM, but I want to make a little purpose-built jig for something, just for the fun of it and because it's easier to use, and sufficient for what I'll be doing. Y'all know what I might search to find just the raw innards, or should I just salvage one of these?

[Anonymous No.1388237]

Bought meself a terrorist watch (f-91w).
The backlight is shitty, I thought about resoldering the led on the watch's PCB so it faces more towards the display to give more light.
Since I will be desoldering the LED anyways I had an idea to replace the stock LED which is standard green with something else since I really liked amber-coloured backlight on one of my shitty casio watches I had a few years ago.

Then I encountered a problem.
F-91W is powered by a CR2016 battery which have nominal voltage of 3V and that's what I assume the watch's electric pixie sorters are running at. The stock green LED (SMD component called 0805 whatever that means) is rated for 2.8-2.9V according to most offerings on ebay which is well within the ballpark number of 3V of the watch's battery and seems to work fine.
Amber 0805 SMD LED is rated for 2-2.2V. How big of a problem it is if the LED is never powered for more than 10 seconds at a time?

Is it going to have a massively shorter lifespan because of me running it at a significantly higher voltage than it's rating or is it just going to blow up as soon as I press the button?
Also is it going to be a lot brighter than the stock one?

Please halp, I'm a drooling retard when it comes to this stuff and despite the terrorist watch being a cheap piece of shit I don't really want to spend another 12 bucks for a replacement when I fuck this one up.

[Anonymous No.1388244]

>>1388237
>is it just going to blow up
hmm, if only there was a way to test this prior to soldering it onto the watch

[Anonymous No.1388248]

>>1388244
Right I can test it with a spare battery, silly me.

[Anonymous No.1388281]

>>1388248
you will need to know how much resistance is in series with the LED on the watch

[Anonymous No.1388282]

Does the esp32 really only have 2 DAC pins? And does that mean that only 2 pins have a true analog output signal, or that only 2 pins can do PWM?

[Anonymous No.1388409]

>>1388282
>what is google
It has 2 actual DACs, and a handful of PWM pins. Arduino's "analog" outputs being PWM is a bit misleading.

[Anonymous No.1388443]

so i know ttl comparators like the lm393 that source current to the inputs can work a little below ground for ZCD circuits. i'd like to do the same thing with a pic's integral comparator, but i'm not familiar with the cmos rail to rail comparator architecture. does anyone that is familiar know if i could expect it to work comparing ground to a signal ~50 mV below ground? for those who don't, please don't just point me to the datasheet's common mode range.

[Anonymous No.1388464]

Where can I get a calibrator for a network analyzer that won't cost a fortune and what kind of probes and stuff do I need for making measurements with a VNA? In tutorial videos about VNAs the DUT is always a nice little box with BNC connectors all all the ports so they just hook up some coax from the VNA to the DUT but what if I want to measure something on a breadboard or a perfboard?

How do I even hook it up right? I have two RF out ports labeled 1 and 2 and two other ports labeled R and A. All 50 ohm.

[Anonymous No.1388551]

>>1388464
>what if I want to measure something on a breadboard or a perfboard?
Use a BNC to alligator clip lead. Sure they're not going to be nice at RF frequencies, but neither is a breadboard or perfboard. Do you not have the manual for your analyser? If not just google for a pdf.

[Anonymous No.1388573]

>>1388443
No matter how it is internally implemented, it's not like it magically stops working immediately outside the guaranteed CMV range - particularly if you aren't at temperature and power supply extremes.
If it's some personal thing, you're fine. If it's an actual product, it would make sense to ask Microchip instead of some random faggots.

[A No.1388588]

Does anyone know how to resist 10kw? I don't have any problems with heat. I just want to reduce 3 phase 220v 60a to just 220v 5 amps

Can anyone help me?

Also is it possible to arrange a whole bunch of tiny resistors in parallel as long as I have enough and all are being used I shouldn't have no problem with those little wires melting right?

[Anonymous No.1388592]

>>1388588
What are you trying to do? What's your load?

You could theoretically use a bunch of those tiny resistors, but you'd need a fuckton of them, those are 1/4W rated, so you'd need 40000.

[Anonymous No.1388603]

>>1388588

this has to be a joke, or you're one of those people who have no understanding of electricity and think a 60 amp circuit somehow forces 60 amps through any load.

however, if you are serious, forget the tiny resistors and just add a shot of black.

[Anonymous No.1388609]

>>1388588
a heating element will do it. or a few light bulbs.
for what purpose?

[Anonymous No.1388611]

I'm looking for a low voltage (1.5V) SR Latch, file unrelated

[Anonymous No.1388613]

Completely stupid question.

I'm measuring just as a precaution the voltage output from my raspi's GPIO's when using a breakout board.

>5V pin connected to multimeter's V-Ω port
>GND connected to multimeter COM port

Somehow the multimeter says -5V [MINUS 5V]

I tried with a AA 1.5V battery and it shows the correct voltages though.

WHY. The only logical explanation is that my breakout board is fuarrked up

[Anonymous No.1388628]

>>1388611
74AUC and 74AUC series would work. Use '74 or build it from two gates.

[Anonymous No.1388629]

>>1388628
Was supposed to be 74AUC and 74AUP. There are others too.

[Anonymous No.1388634]

>>1388629
thanks

[Anonymous No.1388653]

>>1388603
I’m just wondering that because you have like 15a at the wall and some things don’t even take 1a

What is a shot of black?

My load takes 4 amps from what I understand, I’m testing if it will break under an unnatural frequency range not your regular 50 or 60 but I don’t want it breaking because of too much current or voltage

[Anonymous No.1388654]

>>1388592
Haha yeah

[Anonymous No.1388711]

>>1388653
>I’m testing if it will break under an unnatural frequency range not your regular 50 or 60 but I don’t want it breaking because of too much current or voltage

Things that you plug into the wall draw as much current as they can if the circuit can supply it. If your device is rated at 4 amps and XX volts, and you plug it into an XX voltage circuit rated at 30000 amps, your device will draw 4 amps.

A shot of black is what you add when you want them to know you are a pro. In your case, it's a waste of time.

[Anonymous No.1388712]

>>1388603

[Anonymous No.1388713]

>>1388613
maybe your supposed GND is actually connected to +5V?

[Anonymous No.1388715]

>>1388653
>I’m testing if it will break under an unnatural frequency range

why are you concerned about this? what source of power has an unknown frequency range, or are you planning on using a 50 hz device at some wildly different frequency? If so, since you are clearly not well-versed in electricity, I'd recommend against whatever you are trying to do.

[Anonymous No.1388720]

>>1388613
or, you're reading the pinout backwards. never have I ever done that before
>tfw some boards in manufacturing this very moment where I have done just that

[Anonymous No.1388764]

>>1388653
Sounds like you're pretty dumb so you're probably gonna end up killing yourself when you play around with mains. Go play with your video games or whatever you autistic kids do these days and leave electricity to the professionals.

[Anonymous No.1388847]

>>1388653
You need to read about Ohm's Law and understand the relationship between voltage, current, and resistance.
You're a long way from doing anything useful until you understand how that works.

[Anonymous No.1388871]

Multimeter advice? (0-60 bucks). I'll only be using it for small hobby electronics, so I can't justify to splurge on a Fluke. I was thinking the EX330?

[Anonymous No.1388900]

>>1388871

[Anonymous No.1388909]

>>1388603

[Anonymous No.1388926]

>>1388847
>>1388764
>>1388715
That’s what I’m doing
>>1388711
I thought that but I just never knew, thanks a lot for tbat btw, svaving me a lot of effort


Thank you all for your concern but I will be fine

[Anonymous No.1388931]

>>1388711
I just thought because I saw on the internet that too much current can burn out your load, But I think that was right because you have like lamps that plug into your bedside table that’s why I thpught I’d might ask the professionals on 4chan

[Anonymous No.1388956]

>>1388931
Wall sockets are a constant-amplitude AC voltage source, and a resistive load (like a lamp) has a (nearly) constant resistance. I = V/R, so the current that flows will be dependant on the resistance. A socket with nothing in it doesn't push 15A out of it.

But with higher frequencies you may run into problems: you won't be able to run anything that isn't straight-up rectifying the voltage or running it directly into a resistive load. Thankfully this range is fairly small and only includes things with electric motors (fridges), transformers (microwave ovens), and capacitive droppers (cheap LED bulbs). But different frequencies can certainly play havoc with devices that have noise suppression like common DC power supplies; high frequencies could push too much current through the X and Y caps or not enough current through any chokes.

Lower frequencies are insufficient to run many things, but only really dangerously so in the case of inductive loads (transformers and motors), DC power supplies and cheap LED bulbs will probably just run less efficiently.

[Anonymous No.1389079]

How compact can I make a 7 segment display and a dial that counts 0-9?

[Anonymous No.1389083]

>>1388871
i have this and i hate it. the autoranging is damn near nonfunctional and the forward voltage tester doesn't seem to do anything over 2v or so.

[Anonymous No.1389092]

>>1388956
Thanks for letting me know man, it’s good to know

[Anonymous No.1389094]

Multi meter 40 bung

[Anonymous No.1389100]

>>1389079
You can do that in a board that can fit on top of a watch battery. Small enough that you'd need a precision screwdriver to turn the dial.

[Anonymous No.1389101]

>>1389094
How much is that baby?

[Anonymous No.1389106]

>>1389094
Another one

[Anonymous No.1389107]

>>1389101
40

[Anonymous No.1389130]

>>1389079
Decimal counter > BCD-to-7seg driver > display
Not sure how you'd get the dial though. A single SMD microcontroller would be more compact, naturally. Even throw a tiny OLED atop it and have a digital dial and numerical display.

>>1389094
>>1389106
True RMS?

[Anonymous No.1389131]

>jammed dmm in socket
>pop
>it was in amps range
I'm so ashamed

[Anonymous No.1389167]

New FPGA board by Arduino. Thoughts?
https://store.arduino.cc/arduino-vidor-4000

[Anonymous No.1389182]

>>1389167
Considering Arduino's selling point is their software and community... How well it plays together with existing shit?

[Anonymous No.1389195]

>>1389167
Might be interesting

[Anonymous No.1389219]

>>1389195
lel

[Anonymous No.1389223]

Here's an interesting little read, about RF microphones.
http://www.beis.de/Elektronik/HF-Mic/HF-Mic.html
Interesting way to use perfboard, and don't ask me what's going on with those diodes.

[Anonymous No.1389251]

>>1389167
>lolduino
yeah nah

[Anonymous No.1389399]

>>1389131
this is why we have fuses. live and learn

[Anonymous No.1389404]

>>1389223
Yeah, clever use of perfboard. sure makes it easy to swap out different components in a prototype.
I've seen US-made prototypes that use IC sockets, but I like those pin headers better because they can be put wherever.
Simple circuit yet not very easy to understand.

[Anonymous No.1389419]

>>1389130
It’s on flea bay

[Anonymous No.1389662]

I don't understand how to implement negative feedback, at least not outside of op-amp circuits where it's really straightforward. So what are the different ways to implement negative feedback in BJT and JFET amplifiers and other circuits with control loops and how exactly is degeneration negative feedback (you don't appear to be feeding back signal from the output to the input)?

I made a basic common emitter amp and tried to apply some current feedback by taking some current from the output and feeding it back to the emitter node and likewise taking some from the output and feeding it to the base. I'm not sure either of these are negative feedback or not though the latter also provides bias.

Also when you use an active current source instead of a resistor for a fixed bias design does that help eliminate the disadvantages of that topology (variable collector current as temp and power supply voltage varies, variation in Vbe and beta, and susceptibility to thermal runaway?)

Sorry for like the 900 different questions.

[Anonymous No.1389700]

>>1389404
Pin headers are way better since they're cheaper and can be fit to any IC package. My only gripe is that 1% resistors leads are too thin to fit snuggly.

[Anonymous No.1389710]

>>1389662
All I know is that to have negative feedback you need a somewhat linear amplifier, and a way to invert its output around a chosen ground to feed back into its input with some amplification/attenuation factor. Learning that sort of explicit amplifier circuit will be handy for RF purposes.

[Anonymous No.1389730]

I'm looking to get into the lamp game with my own base and shade creations. Having all electrical components be the same would be great. As in a Lamp socket, switch, cord, and plug. Is this the best deal out there? ($5)

[Anonymous No.1389735]

>>1389730
Doesn't look bad, but it may take some effort to make it look good as part of a fixture. There are more expensive sockets specially made for inserting into lampshades.

[Anonymous No.1389742]

>>1389735
You're right. A fixture with a threaded base would be a better starting point.

[Anonymous No.1389768]

I need to get a basic power supply for fiddling with electronics. Is there anything I should watch for or avoid when shopping? Are AliExpress ones safe? Is there a standard recommendation y'all have?

[Anonymous No.1389842]

>>1389167
Here's an article about it, with a video. https://hackaday.com/2018/05/20/video-of-the-arduino-fpga-board-demo-at-maker-faire/

Kinda disappointed at the price to be honest. I don't know if FPGAs are usually this expensive but 60 bones is still a bit too steep in absolute terms. Looks like i'll be sticking to my microcontrollers.

[Anonymous No.1389850]

>>1389768
I try to avoid chinese stuff for anything that has to touch mains voltage. There was a video on youtube of someone taking apart phone chargers and some of them had close to no isolation between HV and LV.
I'd personally recommend looking at more established sellers like digikey, mouser, etc. (see OP).

Otherwise, if you have some old chargers from established manufacturers you could use those to do the step down, and the cut the low voltage side wire and make your own battery eliminator circuit. If you just need a couple of amps and set voltages (eg 5, 9 or 12V) this could be relatively easy. What specs are you looking for?

[Anonymous No.1389968]

>>1389662
first, consider that a common emitter amplifier is inverting with respect to voltage
>emitter degeneration
is negative feedback because output current passes through the collector and emitter and thus increases the voltage across the degeneration resistor, which increases emitter voltage and thus reduces the b-e junction's voltage and thus current for a given input voltage
>collector-base resistor
is negative feedback because the output voltage is directly coupled back to the input. more base current from the input produces lower voltage on the output, which produces a smaller contribution of collector current to the b-e junction
suggestion: add an input resistor, and use something smaller than 390kohm for your collector feedback

>>1389710
that's backwards. you would use negative feedback to help linearize a wide band amplifier. since non-linearity in the time domain corresponds to harmonics in the frequency domain, in narrow-band amps e.g. for RF you could use one or more BPF or LPF to linearize your output

>>1389768
what kind of electronics exactly? I suggest starting with a 12V wall wart rated for at least 1A. use one of those "breadboard power supply" boards to regulate it down to the 5V or 3.3V you would want for digital etc. also get a jack compatible with the plug on the wall wart to use the 12V directly where required
you probably won't need an adjustable supply if you're just starting out, and if you do, those little aliexpress buck and boost dc-dc converters with the trimpot voltage adjusters will be adequate for most purposes. buy three or five, they're handy. you could even splurge and get one of the ones with current limit for your bench. the only disadvantage vs. a "bench" supply is no metering and no calibration. get a multimeter, solved

>>1389850
>using phone chargers as power supplies
I shiggy diggy doo
>try to avoid chinese stuff for anything that has to touch mains voltage
good luck with that

[Anonymous No.1389988]

>>1389842
for what's on the board, the price isn't too bad. there are cheaper FPGA boards, try alibay

[Anonymous No.1389989]

hi guys, just got into IT and I have a question that /g/entoomans didn't answer
any guides on how to use a tester to diagnose a malfunctioning mobo or psu capacitor and fucked molex cables?

[Anonymous No.1390042]

EE student here. So a while back I was testing a DC-DC buck converter, a mini 360 like the one in the pic. I hooked up 12v to the input and was trying to get 5v out. While testing the output I only wired the output to my multimeter. The Buck converter only dropped the voltage by volt and made a high pitch hissing noise.
Today I tested it again using a resistor as a load and hooking it to a common ground with the power supply, there isn't a hissing now, but the voltage is only 1v less than supplied.
I'm positive the output filter cap. is destroyed and the potentiometer as well, but I'm not sure why.
The reason the buck converter was destroyed in the first is because of the way I originally hooked up the output, right?
I just don't want to make the same mistake again.

[Anonymous No.1390051]

>>1389968
>you would use negative feedback to help linearize a wide band amplifier
I said somewhat linear, by which I meant it can have any kind of varying frequency response as long as it's not discontinuous like a Schmitt trigger.

[Anonymous No.1390059]

>>1390042
the sound suggests it went into pulse-skipping mode
it would take a lot to destroy the pot, and the output cap should survive 12V without any probiem. furthermore, the MP2307 has overvoltage protection on the output
the only reasonable failure mode I can see would be a failure of the pot, such as the wiper becoming disconnected from the resistance element. next time, measure that there is a reasonable resistance between the wiper and the element

>>1390051
ah, okay, got it

[Anonymous No.1390063]

NEW THREAD
>>1390062
>>1390062
>>1390062
NEW THREAD