/diy/ - Do It Yourself

More info about the device in OP's pic:

The TL431 has a long history; it was introduced in 1978[2] and has been a key part of many devices since then. It helped regulate the Apple II power supply, and is now used in most ATX power supplies[3] as well as the the iPhone charger and other chargers. The MagSafe adapter and other laptop adapters use it, as well as minicomputers, LED drivers, audio power supplies, video games and televisions.[4]

http://www.righto.com/2014/05/reverse-engineering-tl431-most-common.html

Somebody wants to take TL431 as his lawfully wedded waifu. He has a boner for TL431.

>>1974042
lets say i got a power factor transformer that should on paper with the voltage and current in only output say 250 miliamps on the output. can i use a capacitor on the output of one side before a fullbridge to get more current?

see i sort of rigged it to generate more current with a big cap across primary 1 and 2. so faster than you can see it ramps up and then the cap is tossing back and forth as much current as is flowing in given the frequency. but the output was only 250 miliamps. which is fine for a few hundred volts. respectable. but the stupid bulb wouldnt turn on. its a 125 volt 20 wat one. now with ac it will and if i use another cap on the secondary output it cuts on brighter with ac. but dc isnt going to generate as much heat so it wont glow as bright. but is this due to a net gain in current because its A sending current back into the transformer in pulses and B sending current through the fullbridge it collected back in pulses. so the high side cap output vs normal and the voltage seems the same but current is different (which shouldnt happen without a regulated circuit which this is not)

this is all non critical. im just curious as to weather or not the 1.47 uf i got on 1 side of the out put is sending more current on both sides of the output or if its spike potential when the cap discharges or possibly because its not a regulated circuit if its frequency control. this is about more current i dont care how noobish this sounds

looks like i missed the new general so:
Hi DIY-anons, it's me back with my dumb questions: i should receive the powermos shortly so i was changing the power stage for the heater to use that instead and drive it with a BJT (it will invert output logic but i want to keep it as simple as possible)
So this should be ok or i need some kind of pull down resistor to discharge the powermos quickly to keep it nice and quick? name on the board is a placeholder the real one is a IRFB7545PBF

>>1974159
No it should be fine, but you have to realize that when BJT will be off e.g. when MCU boots up, mosfet will be on due to R6 pulling the gate high. This also means if BJT fails, output will be stuck on. If you plan to leave the device running untended then you need to consider this and possibly also include a thermal fuse.

>>1974166
i am aware, controlling loads this way it's always a big no-no, even more if it's a heater.
Any idea on how to efficently keep the positive logic?

>>1974187
Swap NPN with PNP, connect emitter to Vcc, base to arduino (via resistor), collector to gate of the mosfet and from there resistor to ground.

>>1974191
Thanks, just to make sure it's like this, right? but won't it have problems considering that i have VCC at 12v and the controlling PWM being at 0-5V? like not complete turn-off or on translating in a not complete turn on/off of the mosfet?

>>1974197
Actually you're right, I didn't see that Vcc was 12V, this won't work because PNP will always be on. You should have one more npn level shifter transistor that will control PNP because you can only switch with NPN as arduino can only do 5V logic signals. This solution would only work if Vcc was also 5V. To make this work you should use the original npn circuit to drive pnp which will drive mosfet as is drawn now.

>>1974275
Damn, good thing it's a one time thing, next time i need to get those fancy logic level mosfets so i can just drive it directly, if i'll make it a board/kit i'll see to change that but for my use it's ok....any good components similar to my IRFB7545PBF but with logic voltages?

>>1974297
See this catalog and search for logic level.
https://www.mouser.com/pdfDocs/Infineon-Selection_guide_MOSFET_OptiMOS_and_StrongIRFET_2019-SG-v01_00-EN.pdf

IRL40B215 for example could be what you need. It even has a bit smaller Rds on.

>>1974310
thanks man, i really apreciate the help!

>>1974187
could just use two NPN's. Two inverters -> a buffer

Bros I have a question. I'm practicing for my finals and I chanced upon this question which is kinda weird. The SET/RESET of each three flipflops is connected to the ground but why is that the case? My professor had never included ground/resistors or anything of the sort in the lectures before and not even the textbook has it which is why I'm curious about their usage.

>>1974439
This is there to prevent those inputs from floating. If you leave reset unconnected it can pick up noise from the environment that can toggle input. To prevent this you tie those inputs to known potential GND which is equivalent to logic 0. Leaving pin unconnected is undefined behaviour.

>>1974159
No need for a pulldown resistor, the BJT will pull it down with hFE*I_base, which is probably more than you could reasonably get with a static resistor.
What you might want to be worried about is that before the arduino has booted, the MOSFET will probably be turned on.

>>1974297
If it starts with "IRL" instead of "IRF" then it's logic level.

>>1974439
IRL, many ICs do not take nicely to their pins being left floating. Especially with CMOS ICs; random RF/EMI/etc. can trigger inputs and cause erroneous triggering of them. There's also the risk of ESD. It's considered good practice to tie unused inputs somewhere that won't cause issues, for almost all cases, not just digital logic. Unused outputs can usually be left alone, but sometimes a resistor on them to a rail can help. While when dealing with theory you can just ignore unused pins just as you can ignore their connections to V+ and V-, it's sort of implied that those connections are there. You won't lose marks by drawing them in at the very least.

With 74LS logic it usually isn't a problem since all inputs have natural pullups IIRC. Not sure about 74HCT, but 74HC and 4000 series should definitely have unused inputs tied somewhere.

>>1974448
>If you leave reset unconnected it can pick up noise from the environment that can toggle input.
What the fuck, that's so cool. Thank you anonbro.
>>1974453
>Especially with CMOS ICs; random RF/EMI/etc. can trigger inputs and cause erroneous triggering of them. There's also the risk of ESD. It's considered good practice to tie unused inputs somewhere that won't cause issues, for almost all cases, not just digital logic.
Damn I didn't know that there are so many factors that can affect the the inputs.
>With 74LS logic it usually isn't a problem since all inputs have natural pullups IIRC. Not sure about 74HCT, but 74HC and 4000 series should definitely have unused inputs tied somewhere.
I-I don't get what you're saying haha... The professor made a note to ignore the numbers because he just copied it.
Thank you though, this is all super cool to learn.

>>1974462
>I-I don't get what you're saying haha
There are different logic families, and quite a lot of them. CMOS means "complimentary MOS", MOS means "Metal Oxide Semiconductor", referring to MOSFET transistors. MOSFET transistors have an electrically isolated gate that controls electric current via capacitance, meaning they can be pulled any which way by electric fields. An open-gate MOSFET can be used as an electric field detector that's just as good if not better than three bipolar junction transistors chained together.

CMOS is used in most modern ICs, and has been around for a fair while. Some specialist stuff won't, and the old stuff you're likely to use in labs could be CMOS or TTL "transistor-transistor-logic". 7400 ICs and 4000 ICs are two families of integrated circuits, mostly for digital logic. See the wikipedia pages for them, and the pages for the lists of their ICs if you're curious; you'll find everything from NOT gates to XORs to JK-FFs to shift registers to 7-segment decoders.
While I think the 4000 series is CMOS only, the 7400 series has a variety of different logic families behind it as it's been about for a long time. Say, a hex inverter 74LS04 would be the "low power schottky" TTL version, while the 74HC04 would be the "high speed cmos" CMOS version.

Simpler logic families include resistor-transistor-logic and diode-transistor-logic, which you can use to make your own logic gates in a pinch. You can look up transistor-level circuit diagrams for the more complicated logic families like TTL, but don't expect to understand them. If you have an understanding of how a transistor and resistor works, you should be able to see whether or not an input will need to be tied to ground or not from that diagram, even without understanding the whole thing. If you don't have that understanding, then it's safe to say that expecting that is outside the realm of your class.

I'll be having job interview for a position where I'd be designing mixed mechanical & electric car systems.

Any tips what can I expect? So far I am reminding myself of MOSFETs, DC control via PMW and that everything in car is on 12V, 24V & 48V while modern applications are switching to 48V.

>>1974523
I'm unemployed

>>1974523

I'm also reading genlib books & watched that guy's video, good to know to always use resistors for safety. I lack such insights like having Zener + thermistor combo for safety or that without resistors fuckery with ringing can occur.

>>1974042
Project roll

>>1974525

Hope it would change for you soon. I bec

>>1974532
>>1974525

Ffs, I meant to say that I became different, I guess happier person after I've got job 3 years ago after many years of NEETing.

>>1974523
>>1974530
if you have time read up on automotive surge protection. i'm not in the industry but that's a unique consideration for auto that they might prod you about.

>>1974534

Thanks, that's valuable advice. I found out about LV124 & LV148 test, as well as ISO 16750-2, will try to read those.

>>1974533
Happy happier-ness bro, as long as your content and satisfied then we're glad for you.
>>1974525
You too bro, I hope you get employed soon (if you want it), otherwise, as long as your happy we're happy for you too.

>>1974523
CAN bus?

>just discovered the hotkeys "A" and "P" for KiCAD's Eeschema
this is game changing, what the hell have I been doing all this time

>>1974656

if you're cheering for hotkeys, that's a huge sign you're using shit software. nobody should be memorizing shit like that in 2020.

>>1974742
t. never used vim
proper assignment of hotkeys is objectively the fastest possible workflow when it comes to most types of software that doesn't rely on the keyboard for continuous text input. Relying on a mouse to select which tool you want from hotbars is easier to learn but ultimately takes more time.

Hi, I saw a video of a repair man bridging the first mosfet (after removing it) on a laptop motherboard which was otherwise dead (the 19.5V was stopping at this first mosfet). The question I have is: is it safe to repair it like this? Or is it something that should only be temporary? I read that it could damage the battery...
Thank you

>>1974042
you stole my pic! T-t-thanks

>>1974756
no idea man. we deal with circuits, not with anecdotes.

>>1974764
I was talking about this video (at around 19.:40)
https://youtu.be/mAFrdkbnTz0?t=1190
thank you

>>1974742
>nobody should be memorizing shit like that in 2020.
we got a smoothbrain over here guys

can anyone help source these black caps? they all had blown their oily goo on my graphics card
When the card gets hot now it just shuts off

>>1974813
They're tantalum caps. Them leaking however, seems extremely rare. You might be able to find the original make/model datasheet by googling the letter sequences + 'tantalum capacitor' and maybe throwing in 'SMD'

>>1974819
are you sure they arent
"Conductive Polymer Aluminum Electrolytic Capacitors"

>>1974820
that looks probable. not him but i didn't even know they sold electrolytics in these packages until i looked. it's just a 560uF 2V ("d") cap. you could check the dimensions with calipers (or just a fucking ruler) but they only seem to sell in one size. replacements can be ordered off digikey or mouser.

personally i'd cheap out and solder on some THT caps instead but these things seem to have especially low ESR so that might not work well.

Hey /Ohm/ists
I experience some weird behaviour on my electrical network. My closest neighbor consumes a 81kVA basis subscription, 2000€/m of electricity.
I'm on a 6kVA sub.
I'd like to install some monitoring device in between the electrical company shutter and my electrical panel.
The idea would be to collect datas on the device, over TCP/IP or radio, then graph push them on influxdb to seize spikes and lows as pictured.
I think the Hager HTG411H fits that role, but ... it's 2200€.
Do you know something able to fit my need ?

>>1974902
buy a current clamp with data logging capability

>>1974907
5 secs in google.
https://www.picotech.com/data-logger/cm3/current-data-logger

why do toroid inductor cores have one side colored differently

>>1974915
why did the chicken cross the road

>>1974915
it's just an artifact of how the powder core is made

>>1974826
there is a back-plate that covers these so i don't know if i can swap anything different without clearance issues

>>1974919
Solder the substitute caps onto a piece of protoboard and stick it somewhere out of the way, then wire it to the pads. Use low ESR electrolytics.

>>1974928
they're bypass caps for an asic so in this case nanohenries might matter as much as milliohms. it could be worth it to shell out the ~$12 incl. shipping to make it work the first try.

>>1974930
True, but in the meantime he can confirm that it's just the caps that need to be replaced. Should be enough to get it up and running but it would be unwise to stress test without the right caps.

Is there a 5-variable karnaugh map solver that you guys would reccomend? I can do 4 variables but jesus, it gets so nasty when you do 5.

i wish tht capacitors came in more colors

>>1975053
There are better tools to do this
https://en.wikipedia.org/wiki/Quine%E2%80%93McCluskey_algorithm
https://en.wikipedia.org/wiki/Espresso_heuristic_logic_minimizer
https://github.com/djcopley/QuineMcCluskey
Karnaugh maps are usually not used for more than 4 variables, because it essentially becomes 3d and at 7 variables 4d hypercube.

I have a question about thermistors

https://static.rapidonline.com/pdf/31916.pdf

I was looking through this datasheet and it lists the R25 for J, K and L type thermistors but I thought J, K and L types were just for thermocouples?

>>1975070
Those are just tolerance groups and have nothing to do with thermocouples. In thermocouples those letters tell you from what alloy it's made, in case of your thermistor it tells you it's resistance tolerance at 25°C.

>>1975063
I wrote (half of) a karnaugh map solving programs year or two ago, and instead of using Gray Code for 2-bits across each side, I just split it into N 1-but dimensions. So a 4-variable map would be in 4 dimensions. Much easier to test for matches that way compared to looking about in multiple directions and looking for wraparound and such.

That said, it was a bit over my head as a programmer, so I abandoned it. I’ll look into what you posted.

Also he should just use Logisim.

I want to drive a car aircon compressor using an alternator converted into a 3 phase motor.
It looks like electric speed controllers meant for scooters and bikes are a fairly cheap way to run the alternator, but I don't really need variable speed control - is there a better option here?

>>1975447
>is there a better option here?
i doubt you'll find one that's cheaper. ESCs benefit from consumer economies of scale.

I've made a barebones active low pass filter and it works fine & shows up fine on my oscilloscope except for when I plug my headphones into the jack to test it out. The waveform changes into pic related. My oscilloscope skills aren't that good so I don't know if it's just a result of me not using the right point for my probe or if somethings shorting. Thoughts?

>>1975660
Forgot to include the schematic.

I've made a barebones active low pass filter and it works fine & shows up fine on my oscilloscope except for when I plug my headphones into the jack to test it out. The waveform changes into pic related. My oscilloscope skills aren't that good so I don't know if it's just a result of me not using the right point for my probe or if somethings shorting. Thoughts?

>>1975664
Put a .1uF/100nF cap between signal+ and ground.

>>1975664
So it works with headphones plugged in, just scope is showing this? Or it doesn't work when you plug your headphones in? What is impedance of your headphones? It looks like you're trying to pull a lot more out of the opamp than it can provide.

>>1975063
>>1975091
Thanks bros, I'll just use logisim because doing 5 variable already feels like playing some 4D chess

>>1975681
>>1975683

Placed a .1uf cap between the output's ground pin and the ground rail itself and it seems to work. I'm not to sure on the WHY aspect though; Is it a decoupling capacitor?

What influences the choice of capacitors in an inductive heater circuit? Why can't I use the tiny high voltage ceramic capacitors instead?

>>1975691
Isn't an inductive heater a form of LC oscillator? I'm not 100% sure but I believe a larger capcitor increases the inductor's magnetic field strength.

>>1975691
Dissipation factor. Capacitors aren't ideal components and will have losses. In case of induction heating you're dealing with high currents and this means high losses. In commercial high power heaters they even use water cooled capacitors like pic related. Another reason why ceramics are bad idea is that they can crack under high temperature stress. Polyputthekettleon is the way to go.

>>1975690
Probe ground is connected to mains earth so maybe that's the problem. How are you powering your circuit?

>>1975706
They're all being powered off of +-12V AC busboard. The oscillator source is also connected to the same power source so they're both sharing the same +-12V (~450mA I believe) and ground.

>>1975701
Put that in your tazer and smoke it. You could shock the butthole right off of somebody.

Aliexpress toroidal ferrite cores
Y/N?
For context, in the local market, it is cheaper to get a cheapo buck converter from china and remove the ferrite core from it, than to get a ferrite core by itself.

>>1975712
They don't seem like they'd be prone to being fake like capacitors or ICs. The only big downside of bulk buying from china is the lead time.

>>1975664
>>1975681
Can't see why an output cap would help, though it wouldn't hurt if the current drawn into and out of it wasn't enough to load down the output.

What's the output impedance of your op-amp? If it's a TL072 then it has like a 200Ω output impedance, meaning it's not a very good choice for driving many kinds of headphone (common impedances for headphones range from 8Ω to 32Ω). A JFET op-amp isn't a good choice for this, especially if your signal is already buffered. Be better to use an op-amp with a lower output impedance, or a proper audio amplifier IC.

>>1975712
good luck hand-winding toroids, it's a fucking pain

>>1975733
Ideally, the output would be a mono output feeding into a four-channel op-amp mixer I have. I'm just using my headphones as an alternative for easier testing. In regards to the op amp, I'm using a TL072 (I'd been using LM358Ps but most examples of synth circuits used TL0x variants so I switched). Considering that I'm still relatively unfamiliar with op-amp specifics, Is there any one particular quality that I should consider when choosing ICs or is it just a handful of things that I'll come to recognise in due time?

>>1975735
>most examples of synth circuits used TL0x variants so I switched
JFET op-amps are good for low-noise applications and have basically no input bias current, hence their propensity towards being used in delicate analog circuits. But they're not designed to drive anything substantial. On the datasheet, you'll find pic related, which should tell you how far out of its comfort range you're running, even if your signal amplitude isn't high enough to be effected. JFET op-amps also usually have significantly worse quiescent current, in case you're worried about that.
Looks like it isn't recommended to use less than 2kΩ with the TL072, while the LM358 should probably be kept below 20mA output.

If you don't have an LM386 or similar, I'd use some transistors (possibly darlingtons) to make a class-B amplifier with op-amp feedback and make it a seperate board just for buffering a headphone signal. That way you can reuse it with other projects to probe signals without interfering with them.

I'm aiming to start prototyping an IoT device's PCB and I came across this ethernet block circuit. I've never actually soldered an ethernet interface before, just wondering if I'm on the right track here. Does this look appropriate? If not, where can I find better?

>>1975758
I'm not too sure what the output loads of my mixer & my headphones are but at least I know what qualities to research. Similarly, I've heard of Class D amplifiers but I'll look up class B and get a breadboard tester going.

If there's one think I've learned while making synthesiser-based modules, it's that there's a large volume of "build it like this and it'll just work". Any attempt to delve into specifics throws up a lot of topics that require individual research which is fine from a research point (currently looking up q factor for resonance implementation) but it doesn't do anyone any good if they're not aware of exactly what they need to research.

>>1975776
don't make yourself suffer, just throw an esp8266 in it if you can

>>1975777
in my experience earbuds are pretty high impedence. Just buy a 5-pack of some chinkshit you can burn out, and the tl072'll be enough

>>1975781
I can't though

>>1975785
not with that attitude

>>1975781
>esp8266
That's boomer speak for esp32-c3.

Read this book if you want to actually know your stuff

>>1975852
i already know every single thing

>>1975777
Your mixer will probably have input buffering of some kind. If you have a multimeter you can just measure your headphones' impedance and get an accurate enough result. A class-D amplifier generally refers to a complete switching amplifier topology. Definitely possible to design yourself, but also not trivial to do so. A class-B on the other hand usually refers to a totem-pole output stage with a bunch of supporting circuitry to bias the transistors and ensure low output distortion. What I'm suggesting is basically just the totem-pole part, with an op-amp to handle the distortion and forgetting about biasing. Basically pic related, but probably with darlington (or slizzy) pairs.

>>1975784
Most earbuds I've measured are about 32Ω. Not low by audio standards, but definitely low by op-amp standards.

because PCBs are easier to etch if you don't have to care about drilling holes

>>1975874
fear me

>>1975777
> Similarly, I've heard of Class D amplifiers but I'll look up class B

dont waste time. you probably already have an amp you can use instead of your headphones
- computer speakers
- stereo
- clock radio with AUX input
- TV with audio inputs
- a laptop with AUX and MIC inputs

when you waste time, you injure infinity.

>>1975874
I fucking hate soldering SMD

Dumb question: what are those connectors used in cellphones that clamp down onto those flat flexible contacts? Are they FCCs?

Point is I need one for an LCD screen;
https://www.newhavendisplay.com/specs/NHD-0.95-9664G.pdf

Or am I just stuck with soldering directly to a custom PCB?

>>1976005
>https://www.newhavendisplay.com/specs/NHD-0.95-9664G.pdf
>0.7mm pitch
Wow that's retarded
Either adapter board (buy/diy) or just solder directly to your pcb

>>1976021
>0.7mm pitch
>Wow that's retarded
Ay my thoughts exactly
I got it specifically for its display size. I'll probably just end up soldering directly to the board. Which is gay because I wanted to be able to disconnect the display from the board.

>>1975997
Better than fucking about with through-holes imo

>>1975997
SOICs and 0805s and such are easier to solder than THT. SMD soldering only gets hard with fine pitch.

>>1975664
circuits refuse to work if you put your ground upside down

>>1974042
Hello anons. I need your help figuring out a replacement for a hard to find transistor.
It was installed in a very rare piece of gear and honestly It not being able to run again will make me serverly depressed.

The transistor in question is a sescosem BF258.
This is a To-39 transistor usually used in analog video equipement for output stages although this particular one wasnt. What worries me is the very low switching frequency and I know that in some circuits going above by a large margin can cause oscillations.
I cant seem to find a close enough replacement.

You can find the datasheet here at page 567:
http://www.retronik.fr/Composants/SESCOSEM/1976_SESCOSEM_Transistors_de_signal_et_a_effet_de_champ.pdf

This transistor is marked T103 in this schematic. I must add that the transistor is heatsinked.
http://3a-art-et-acoustique-appliquee.fr/Schemas/Schema_Andante_Reference_TR.pdf?

>>1976032
You can make custom adapter board
Or buy one of newhaven adapter boards but goddamn it's expensive

This of course comes with added height and newhaven adapters are not exactly small

>>1976166
Why it needs to be the same?

>>1976173
And
https://www.aliexpress.com/item/32574469365.html?spm=a2g0o.productlist.0.0.38437837UqduDp&algo_pvid=aa6f4b1c-1f8d-441d-9c68-c2e6a2409bbd&algo_expid=aa6f4b1c-1f8d-441d-9c68-c2e6a2409bbd-0&btsid=2100bddd16078705415518273e6ddb&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

>>1976173
It does not need to be the same. It just needs to be close enough to work as intended in the circuit and be a part that's available at trusted providers.
It being heatsinked is a hint that this particular transistor has a lot on its hands. This transistor choice I believe was not made lightly. There are a few somewhat similar high votage transistors in the supporting boards. So they chose this one fairly expensive transistor for a good reason I believe.
>>1976176
There are quite a few "BF258" floating around but because they are no longer manufactured, these sources are questionable. The board its installed in and its surrounding equipement is also valuable and I would like to avoid putting the whole circuit at risk because I ordered transistors off a shady source.

>>1976182
>There are quite a few "BF258" floating around but because they are no longer manufactured
You can always test the device you buy outside the board.

>>1976184
I have little to no testing equipment. Getting a good read on the noise , thermal stability and such is out of the question for me. The only thing I can do is do a rudimentary test for Hfe.

>>1976166
2SC3503/KSC3503 would probably work fine, but it has a bit higher gain.

>>1976187
if you have no testing equipment why are you repairing expensive things?

>>1975997
Get a better iron
I absolutely abhorred soldering when I used a shitty no name chinese 20W iron. I bought a no name chinese 60W one and soldering is much easier and quicker now

>>1976192
Because its my expensive thing and no one who knows how this particular device works wants to take it because of the risk involved with this both for the repairman and especially the device that is shock full of impossible to replace components. Shipping is also out of the question. If it that transistor wasnt to be replaced the repair would only require minimal test equipement. In fact I was nearly done but something caught on the heatsing and tore off the transistor off its leads. The board was designed with repairability in mind, in the early 80s that is. Plenty of test points and most adjustements can be done with a simple multimeter.

>>1976189
Looks like it fits the bill. Do you think it would be able to handle the heat without a heatsink ?

>>1976205
https://www.el-component.com/bipolar-transistors/bf258

>>1976239
Thanks but this site is fucking shit for this kind of uncommon transistor. They dont even have the proper Ft value up and the emmiter base voltage is wrong. But then that might be a sescosem thing. The KSC3503 suggested above is a much better match than anything stated as a replacement on this web site.

Now the only thing to figure out is if the 7W KSC3503 can handle as much as the 5W BF258 assited with a clip-on fin heatsink or if I will have to source a heatsink for the KSC.

>>1976299
Put a thermocouple on it and test it out.

>>1976202
Poo poo pee pee

>>1976299
Well, how much power will actually be being dissipated in the transistor? You can then reference that to whatever the replacement's datasheet says about power. You should be able to calculate that so long as you have a circuit diagram / service manual.
You could also probably find the total thermal resistance of a TO-3 + heatsink to ambient and comparing that to the replacement. Considering the replacement is just a TO-126, I wouldn't rate it above 1W without a heat-sink. So if the original had a heat-sink, you'll definitely want one here, unless the original was a germanium transistor or some shit and needed to be kept below ~35C.

I'd also recommend looking at the service manual for another reason, to check that higher gain is fine in that context. For most purposes, i.e. when there's feedback, the higher hFE doesn't matter. But if it's matched to another BF258 in something like a current mirror or otherwise being depended on as a current sink, then you'll need to care more about matching the gain.

>>1976340
I know I should be doing all of this but unfortunatly Im too much of a retard to actually figure it out. That's why I linked the schematic with the transistor's spot above in the hope someone would know what to do. I know little about electronics and dont know if the slightly higher gain will work nor hnow much power this circuit will have the transistor actually handle. The BF258 is the only one of its kind one the board. Here:
>>1976166
The BF258 is a simple silicon transistor. Its also not a big boy TO-3 but a TO-39. Considering the heat for the KSC dont they usually specify if the stated power handling is with a heatsink? In that case wouldnt it be a 7W ?

>>1976350
no one reverse engineering a old as shit service manual from a unknown product for free. Usually amplifiers (and most transistor circuits) should be made to work within a wide range of gains. Most likely is that even if you find the same transistor model it will have a 10%-50% variation.

>I know I should be doing all of this but unfortunatly Im too much of a retard to actually figure it out.
so maybe you should not be playing with it

>>1976371
>no one reverse engineering a old as shit service manual from a unknown product for free
Let me try. This is typical class AB configuration, differential pair on the input, T103 is voltage amplification stage and then you have discrete Darlington pair on the output. In this context more gain on T103 is actually better because it will make the amplifier more stable. Only real problem here will be temperature and probably adjusting biasing for T108 and T102.

>>1976371
>No one would do this for free
Perfectly understandable.
>Maybe you should not be playing with it
Should I really ? I mean I did manage to make one of these working and was nearly done with the second one before my fuck up. The repair was fairly simple before that. No one who actually knows how these work is actually willing to take them if they are even still in business. The schematic I posted is the only documentation left and on top of that this unit was modified in factory and the power supply is a different type too meaning the schematic is innacurate in a lot of parts. As such I can't even swap the modules out without making modifications to the passive filter, amp and power supply. That wouldn't be possible anyway because there's no spare parts around at all. The last guy willing to take these is one of the engineers that worked on these back in the day and he's asking half of the device's value (rightfully so I might add) and he lives on the opposite side of the country. It's simple either I fix it or it'll go into storage where it'll rot away and I obviously don't want that especially knowing I was close to wrapping it up.

>>1976393
Yes it's a mostly typical AB amp with a Maxwell bridge that gets feedback from a driver. It's a servo speaker. These circuits are still used nowadays but this is a weird one and very early one.
There's a bias adjustment pot right next to T108 noted P102. Will that take care of it ? No idea where to take the measurements or even what target to hit though as the service manual is gone forever.
As for temperature looks like a heat sink is the only way. If it works I'll try to salvage one from some dead equipment.

>>1976416
>T108 noted P102. Will that take care of it ?
Yes this will set the quiescent current through output pair, you basically want it to set it so that output pair is open and conducting current (operates in AB mode) - few mA should probably be enough. Maybe try measuring voltage drop across R118 and then aim for something like 10mV to get 3mA then try feeding it a signal and see if there is crossover distortion present and increase if necessary.

>>1976455
Thanks very much. I will have to run some tests on the PSU module before replacing it. One of the transitors that is known to shit the bed let out the magic smoke. Fortunately I had modern replacements for those. Once I get this done i'ill set the bias and replace that crummy pot while I'm at it. I can probably get away with more than the bare minimum with the current. The output TO-3s are barely warmer than room temp under a mild to light load and the amp is known (servo oblige) to be powerful enough to burn the driver without breaking a sweat. It will be a bit of a pain finding an heatsink but once this is done I hopefully will only have to adjust the DC offset and pack it up. I'll post updates if this gets anywhere.

>>1976169
Hmm, wonder if there are companies that make custom FFC adapters. Something so I can just convert the 0.7mm pitch to something more common. Though that may be too mickey mouse.

>>1976393
This is an interesting looking bias circuit, just having a potentiometer across a BJT.

Is the mix of NPNs and PNPs seen here common? As in how the pushing and pulling stages aren’t mirrors of one another, both the final pairs and the stages before them.

>>1976506
Is it 0.707mm? If so turning it 45 degrees should get it to line up with 1mm pitch, which might help.

>>1976519
Drawing says 0.70mm ± .05mm.
> If so turning it 45 degrees should get it to line up with 1mm pitch, which might help.
I'm not following. How would that lineup?

>>1975997
Step 1. Use Flux
Step 2. Solder 2 corner pins
Step 3. Use even more flux
Step 4. Get some solder and slide that shit across.

>>1975997
THT is a fucking pain in the ass to desolder

>>1976539
what's flux?
>>1976542
you're doing something wrong if you feel pain in your arse. get a fume extractor.

>>1976580
Compared to desoldering SMTs, THTs are decidedly more difficult.
I can just whack an SMT with a heatgun, and pluck it off with tweezers.
With a THT I need to use a solder sucker, then keep each pad hot so that the leg doesn't re-weld itself to the plated hole all while trying to pry out the component

>>1976587
Cut the legs first.

>>1976590
If you don't plan on reusing anything, then sure.

>>1976542
Take the Manhattanpill

>>1976198
>shitty no name chinese 20W
60W is the bare minimum, this should be in the sticky. Glad I caught that advice before it blew into the ether

>>1976587
yea but your surface mount is probably using non leaded paste because the lead free paste melts at a lower temp. some people wont use lead free solder and thus the paste is a abomination and those that go down that road are condemned as blasphemers

Thanks to this board i got a nice working prototype and the right components, the Arduino based PID Is working fine and the board Is very nicely done but i only have a bit of an issue,or Better another doubt:
i'm using a 100w heater at 12V so it's gonna Need big traces on the PCB, but i'm also never gonna use It even near 100% on for the small enclosure (i can limit in the PID the max PWM value but i have very conservatives parameters since the enclosure Is small and the temperature difference won't really be big, so do i really Need the 7mm Wide traces that could more reliably handle 10A or i can Just keep the board i made now with a more "standard" 4mm width for the Power Lines?
Just give me your opinion fortunately i managed to remove quite some components so It's an Easy board but the size alone of those "required" traces makes me want to Just make a 12v and GND Plane of opposing sides and route signals across those

Should I pull the trigger on some SMD ICs instead of DIP ones? I'm tempted since I dont wan't to deal with aliexpress fake TL072s (wish everything wasn't a fake, so it seems) and the price seems to be halved.
It would be my first time using SMD components.

>>1976531
Diagonal traces coming from it would be ~1mm apart
handy if you're running them to an MCU with 1mm pitch

more useful for QFPs/QFNs though, as opposed to DILs and SILs.

>>1976580
>what's flux
well there's your problem

>>1976606
based fellow manhattan anon

>>1976641
Can I see your PID code?

>>1976665
I only buy SMTs if there isn't another option or if I already have enough THTs of the same IC for prototyping. If you're willing to get some SMT-THT breakout boards for breadboarding then that second point isn't an issue. Personally the convenience of SMT soldering trumps the price point, so I'm gonna do this: >>1975874 for my next board.

>>1976665
>not having a legit supplier for common parts
ebay has breakout boards if you can't be arsed to etch. There might even be a free gerber file so you can order hundreds from jlcpcb

>>1976709
I'd like to see some crowdsourced breakout boards meet the arena of public opinion, to see which ones get the most compact or the most different footprints or the best waifus or whatever. Something like thingiverse but for PCB files.

>>1976641
just add solder to the traces. thats what every one does when you need more amps on a trace. just tin them and add more solder to the ones you need more current in. maybe even strip some thin ish (0.5mm -1mm)solid core wire and cut to length and tin them and solder onto the traces while your at it if you need 10 amps

If I'm using an LM386 "power" amplifier IC with a dual-supply circuit. Do I still need an output capacitor? Where do I tie Vin-, to 0V or to Vee?
>http://pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/DS006976.PDF

>>1976713
you can already buy 50pcs soic-8 to dip-8 for like $3 lmao
semi-related, what's the appeal of pre-soldered headers? they're such a waste of space

>>1976763
>Do I still need an output capacitor?
to speaker? yes, you don't want any DC, even a little offset, going through your speaker
>Where do I tie Vin-, to 0V or to Vee?
you sure it's rated for dual supply? all I see is Vs(+) and GND(0). If you're doing fucky things, be prepared to burn up some components and figure things out yourself.
Post schematics if you want detailed advice

>>1976782
Ok I'll just use it single-rail and deal with the "pop" when turned on. I'll still use a couple of op-amps, for better gain control (inverting amplifier with variable gain before the power amplifier) and high input impedance (buffer before the inverting amplifier). I was thinking maybe I'd use a class-B with feedback instead, but then crossover started to maybe be an issue, and the input impedance would need a third op-amp, and shit got more complicated that it's easier to just buy an LM386 instead.

>>1976782
>>1976787
And it's for a guitar - headphone preamp, hence the input impedance requirement. I'll be using a 1MΩ resistor to GND across the input, which I think isn't a bad idea. I think a total gain of 1 sounds reasonable for driving earphones (the kind that don't require an amplifier) from an electric guitar signal, since they're both in the realm of 0.1-0.5V or so. The LM386 has a minimum gain of 20, so I'll need to step that down alongside my variable gain inverting amplifier, probably a 1/10 divider after a potentiometer across the inverting amp. Maybe with some gain-limiting resistors. Will post circuit sometime soon.
A standard op-amp of mine doesn't quite have the grunt to drive 8-32Ω earphones.

>>1976787
>for better gain control
you could just use a potentiometer
>but then crossover started to maybe be an issue
that's what class AB is for. Also, look up a Vbe multiplier circuit, used specifically for eliminating crossover
And be warned that the lm386 is notorious for bad grounding/self-oscillation issues

>>1976821
>you could just use a potentiometer
Oh. Yeah. I should do that. I mean, I'll still need one of a dual op-amp IC for the input buffer, but I guess I could use a second to buffer the divider, maybe also provide extra feedback to the LM386. Its input impedance is 50kΩ after all, so I couldn't run a guitar pickup signal into it alone without getting unwanted distortion.
>that's what class AB is for
Yeah I thought about adding a couple of diodes and a pullup, but that's just more components for an ultimately worse circuit. More complicated bias circuits even more so.
>Vbe multiplier
Oh, so that's what I saw in >>1976393 that interested me. While I'm not too big on discrete transistor circuits, that's still some useful info to know.

>notorious for bad grounding/self-oscillation issues
Self-oscillation I can potentially see, but bad grounding? Wouldn't grounding be solely an issue of the supporting components?

>>1976821
>>1976829
I shouldn't get oscillation with this kind of feedback, right? Not even sure if that snubber network is necessary. Though I'm basically running it like it's a split supply by doing that, potentially messing with my biasing. Guess I'll have to breadboard it and see after all.

The oddball audio sockets are just what I've got lying about, same for the 1mF cap. I also nabbed a bag of ~30 double-gang 16mm potentiometers with integrated switches, which I'll probably use for the on/off switch, because I can. With one gang being 10k and the other being 5k, oddly enough.

>>1976836
>I shouldn't get oscillation with this kind of feedback, right?
idk where you got that circuit from, and I'm not an expert so take this w/ a grain of salt.
But if you feed a signal with 20x gain into the inverting input, won't that just kill the signal?

>>1976836
>>1976844
Consider pic related, a 2x amplifier:
if the voltage seen at V(-) is 1/2 the voltage of the output, the output is twice as high as V(+).
If the voltage seen at V(-) in your pic is 20 times Vout, shouldn't that just attenuate the LM358+LM386's output by 1/20?

>>1976519
>Is the mix of NPNs and PNPs seen here common? As in how the pushing and pulling stages aren’t mirrors of one another, both the final pairs and the stages before them

Yes. This output circuit is called quasi-complimentary push-pull. TR108 is sometimes only a string of diodes (4), this circuit lets you set the zero signal current in T106-107 with the potentiometer in the TR108 circuit.

>>1976836
Build the "Gain of 200" Circuit in the datasheet, direct drive to headphones, see if it works for you.

>>1976836
>>1976853
Oh, and use a 220uf Cap, and a 47nF cap where it says 250uf and .05uf, respectively.

>>1976670
Nothing fancy really, i Simply made a Quick 3 Button event handler with "AceButton" library to set an index to either 1 or 0, if the index Is at One i print a special character on an LCD to notify you are setting target temp and pressing the other Two buttons while index Is 1 let's you add or remove One from setpoint, then in the loop i Just print temps, check buttons and call the PID function from another library (don't Remember the name for that i'll write It later) to calculated output and Just write to output the value
>>1976729
I kinda wanted to have boards made from JLPCB so i either have to remove silkscreen or edit It in some way i don't know to make this possible, but for the beta board since i'll use perforated board and the 2 BJT+MOSFET setup i'll Just add some bigger Wires like you said

Aside from a PSU providing power to the rotor, is this all I would need to run a modified car alternator as a motor?

Can I replace BSS138 with BSS138K in 3.3v to 5v level shifter?

>>1976868
what model of car alternator?

>>1976874
Whatever I can find at u-pull-it.

>>1976877
I do not know what that e-bike thing is or does but you only need 3-phase AC to run it as motor. Whatever you buy it most likely will have built in diodes, so you will need to disconnect those.

>>1976877
I do not know what the e-bike thing is or does. But you need 3-ph AC to run it + a field current. And whatever you buy will most likely have built in diodes, you will need to remove that to use it as a motor.

>>1976880
and depending on the price of those things you are buying, a new motor is cheaper and better.

>>1976868
>using alternator as bicycle motor
kek

what do you call this thing?
i want to order some from ali and don't know what to search for
also how do you call the female counterpart?

If I want to add resonance to a first order low pass filter, it is just a matter of feeding the output into the input or do I need to put it through another op-amp to phase shift the output?

>>1976954
JTAG?

>>1976956
No i want the name of the slot thing the cable plugs into, for example computer power source has connector named molex

>>1976954
It's called an IDC header, and that is 2x3 or 3x2 (6 pins). Search for "female IDC header".

>>1976954
Female 0.1" pitch 2x3 header
Something like that.

>>1976844
>>1976848
Oh yes you're right, that would result in the input to the op-amp being the same amplitude as the output of the 386, which is already attenuated by the resistors. I'll put a resistive divider on the feedback path.

>>1976853
>>1976854
>gain of 200
>200*0.1V
>into headphones
Firstly, I'd get the worst clipping distortion possible.
Secondly, I'd die.

>>1976956
What do you mean by resonance? A two-pole LC low-pass filter will have a spike at its resonance frequency with a height depending on its Q, and a two-pole sallen-key probably will too with the right coefficients, but I don't see how a first-order filter would. Could put another filter to kill the second pole, if you really wanted. The peaky resonance of an LC filter is due to energy being stored inside it, which can cause the output amplitude to be higher than the input amplitude, in the absence of a significant load.

>>1977041
When I say "add resonance" I mean that I wanted to increase the amplitude of the resonant frequency on a single order RC low pass filter as a controllable modulation on a given signal input (tri, sqr, etc. at KHz). I heard that it was possible by feeding back an amplified output (over a certain gain) into the filter's input. Now that I think about it, it might only work for second order filters and above so I might try switching it.

>>1977050
Draw a bode plot of what you want, it will help.
If you want the resonance to always be on the corner frequency of the low-pass filter, then a sallen-key topology with the second capacitor (the one to ground) minimised will increase your Q factor and give you that resonance. See the wikipedia page:
>https://en.wikipedia.org/wiki/Sallen%E2%80%93Key_topology#Application:_low-pass_filter
Again, it is a 2nd-order filter though.

One final Stretch: components and board are ordered but i'll probably have to wait till next year now to receive them so i made a Quick and ugly board with perforated board and thin Wires for signals, so far it's good but i Need to do the 2 BJT trick a kind anon mentioned to keep the correct Logic for the IRFB7545PBF i'm using on the version 0 board, i Guess i Just Need to wire them like Pic related with maybe a third resistor on VO before the MOSFET gate right? And i Guess i don't really Need a big diode because the current flowing trough the 2 BJT won't be that High right?

>>1977250
Interesting push-puller circuit.

A capacitive load like a MOSFET gate will not require high-current wiring or components, but the components will need reasonably high resilience to instantaneous current spikes, possibly upwards of 1A. Adding a gate resistor isn’t necessary, but will reduce the current spike amplitude in the event that your PSU capacitance or instantaneous current resilience is insufficient. Probably a good idea unless you have a seperate PSU or good filtration for the FET driver alone.

You can calculate whether a gate resistor is necessary by calculating the current through the transistors with their hFE in an instantaneous short circuit.

>>1977271
The circuit was Just found online, but It resembled what i'd do when thinking i Need two BJTs ti make the MOSFET buffer, good thing i did because i didn't think about the diode. Anyway thanks i'll surely check datasheets tomorrow when i'll be back to finish It, third resistor seems like the best idea since i have a single 12V PSU (meanwell like) that Powers the board (simple L7805 for 5V regulation for the Arduino and 1602 LCD not filtered, i have the on-board regulators and filters to take care of some noise and i hope it's enough) and i Just feed the 12V to a 100W PTC heater (yeah i'm not gonna let It self regulate i Guess, but i did Always chose components and sized stuff for 15A so more or less treating It as a normal resistive load) and The frequency of the PWM It's the standard Arduino One so nothing really too fast

>>1977285
Why are you having so much trouble with this, drivers are basic shit

>>1977291
I'm Just trying to make-do with the very limited stuff i have now, i'm using Logic voltage mosfets on the final boards so it's Just a problem on making a single handmade board work with limited components while the real One gets here, also the biggest factor so far Is that i'm a retard and i Just want to make sure i'm not making very bad mistakes, a lot of kind people helped me while i couldn't really find good answers for my case with Just Google

Does anybody know what this circuit is or what it does? what it could be used for? Apparently it has a proper name and it's used for something to do with load curves, but I can't find any info on it online. Thanks for the help

>>1977315
It's just a common emitter amplifier with the collector and emitter resistors swapped out for current sources. op-amps are sort of designed like this though they have differential inputs as opposed to single ended and more transistors and mirrors to drive the output.

>MCG(RIP) Guy here
May I drive servos by boosting voltage with an StepUp? Does anyone had done that before?
I need to design a circuit and using an 1S 18650 configuration makes everything way easier, but I cant drive the servos I need with just 3.7V
Im worried about the current consumption of servos "working bad" with an stepup. Im planning to use small hobby SG90 Servos.
Any suggestion?

>>1977322
Thanks, the collector current is still fixed by the bottom mirror, right? What would happen if there was no RL (open load)? Q2 and Q3 would be trying to fix one value for the collector current, while Q4 and Q5 would try to do the same with another value. Wouldn't this be a problem?

>>1977365
>May I drive servos by boosting voltage with an StepUp?
yes.you just need a step-up converter with the right minimum input voltage, maximum output voltage, and current ratings. all the modules on aliexpress have terrible idle current so add a hard power switch before the converter.

>>1977315
the green stuff are both current mirrors, and Q1 is what the other anon said.

>>1977365
>actually using a 1S system
what kind of bootleg power bank repurposement are you making here
just get an appropriate bms

>>1977315
not this shit again

>>1977365
>RIP
huh, is it dead?

How to get deeper into electronics? I'm an industrial automation tech but my job is mostly parts swapping and ladder logic troubleshooting. How to get deeper into the fundamentals?

>>1977464

read a book, nigger. there's a few listed in first post of this thread. stay away from any that seem to be math crazy, since their purpose is only to separate those who get diplomas from those who dont.

>>1977467
Nice, I suck at math, that's why I'm a tech not an engineer.

>>1975874
>>1975884
Ok this got a lot worse really quickly, somehow managed to get away with only two 0Ω links.
Still gonna etch it, but I'll need a fine paintbrush. I'll hopefully be using nail-polish, as it's really etch resistant. 110mm x 85mm, for a circuit that probably would have taken a 10th the area with a 2-sided THT board. Most importantly, no drilling required, no faffing about with multi-side alignment, and I absolutely do not recommend this.

The caps will be glued down.

Are there specialised parallel clockless PROMs for use as programmable combinational logic? I only need 2^5x8bits. Right now I use one of these old 2716s. Works great but I'd like something less bulky. Preferrably SMD and it doesn't have to be erasable.

>>1977496
>SMD
>PROM
I assume you have some sort of SMD programming socket or pogo-pin setup? Personally I'd just use EEPROM since new PROM is pretty hard to come by these days. Might even be easier to buy a PLA or PAL or whatever than PROM. Well actually I'd continue to use the 2716, but that's just because I have a thing for CDIPs.

>>1977486

that's so simple i could wire up that circuit on perfboard using through-hole parts, and have it tested and working in less time that it took you just to lay out the PCB, much less all the other steps still needed to be done. you're wasting your precious life away, dude.

>>1977371
idk wtf you're asking, but the BC junction has a variable voltage drop. If you look up a Vbe multiplier, or "rubber diode" circuit, you'll see that Vcb can be whatever the hell it wants to be - 0V, 5V, 10V, whatever.
>no RL
the Vcb of Q2 and Q5 would change to whatever they need to be

>>1977468
70% of all electronics will use basic algebra. The other 29% will be using logarithms and basic signals and systems. (which can be tricky). Pick a easy starter project, learn the basics (circuits laws and how diodes and transistors works) and fuck up until you stop fucking up.

>>1977530
the remaining 1% will be very hard stuff or esoteric crap. But learning logarithms and dBs is really important and helps a lot to build your intuition.
>t. nearly graduated EE who dislike math but learned to use it as a tool

And if you are building a project here. (As simple as it can be, stuff like a LED blinker) draw a proper circuit diagram people here will help you

>>1977531
and people here will help you*

>>1977530
wrong all wrong. he needs to see the lies. buy a 555 timer and wind a transformer you have salvaged from a piece of hardware . it could be even from a adapter for charging your smart phone thats dead or no longer used but a medium sized transformer is better for this purpose and the charger tends to have very small ones. make a simple circuit to drive a bjt that is controlling the real power input. the internet says 60 hz is standard for transformers. you wound it and the entire internet says winding proportions dictate output voltage. now after writing down the output voltage change the primary windings up or down by 5. look at your output voltage. why didnt it change? refer to bottom line for answer

grab a random cap that can do 250 - 275+ volts and has at least 0.470 uf (470nf). charge it with a 9 volt. discharge through a led by touching both of the leads of the led to the 2 leads of the cap so that the side of the cap that took in positive voltage is on the lead that needs positive voltage. note with no additional resistance it briefly came on . now charge it with the transformer you wound that probably at least does 60 volts. now discharge through led . watch as it turns on brighter or possible dies. its a capacitor. it holds a set amount of electrons. it shouldnt matter what voltage you charged it at according to the manufacturer. it holds a set volume of electrons. wtf is going on?why even label the caps with farads implying colum volts are real. refer to bottom line

go to pinterest and marvel at all the circuit diagrams. make a few random simple ones. ask yourself why the fuck half of them dont work. why are there comments to the effect of "+1 post" and "amazing". why validate circuits that dont function? refer to bottom line

because your whole life is a lie and you lie blind in a world of shadows

>>1977573

Guyse....
I want to connect this LED strip to the battery case switch. (It used to be connected to cell batteries that lasted a day maybe).
If I connect the little stubble of a cable to the black wire (-) and the other end to the red (+), it lights up.
But I don’t know what to do with the little capacitor or whatever it is if I want to actually move it inside the case.
Do I just connect that to the right most free spot on the switch inside the battery case?

>>1977573
based and enlightened post. the electron jews won't be happy about this.

>>1977577
Come on this is a 3 minute job for you guys, help a nicca out

>>1977588
you should highlight the capacitor you're talking about. /diy/ is a slow board but if you're question's not getting answered it's because your pic isn't crystal clear and doesn't show your entire project, which is important because you may not know what context is important.

>>1977590
By capacitor I mean the little thing with the colored stripes on it, if that even is a capacitor.
There aren’t many parts on the picture to begin with, not sure what more to highlight.
I want to connect the LED that is now connected to the loose switch on the table to the one that is inside the battery case.

>>1977591
battery positive -> resistor -> LED+ then LED- to battery negative.
Or
battery positive -> LED+ then resistor -> LED- ->battery negative.

>>1977573
Calculations are for squares, all you need to know is how to slap shit together

>>1977597

>>1977250
ok so tried out this circuit, 5V Vi and get the proper 10+ volts i want that drive the irfb7545pbf (with resistors for fast discharge and inrush current limiting) but the output at Vo is still inverted, the classic NPN+PNP circuit i saw around has the same problem or that should maintain the high logic of Vi (Vi high>Vo high)?

>>1977632
not sure what npn+pnp level shifter you're referring to but you should really consider dealing with the inversion. that pic is about the fastest discrete gate driver you can get, within reason.

>>1977632
can you describe what are you doing? I missed a couple threads

>>1977637
yeah but i kinda want to have some safeguard against components failure, it's still a 100W heater i don't really want it to go 100% on if something fails
>>1977647
I'm making a small arduino based PID controller to heat up a small enclosure, the PID is for having a somewhat stable temp and to avoid having the spikes of an ON-OFF controller, i did the code and i made a nice looking board but to get the board, key factors where make it small and simple so in the final version i have a nice logic voltage transistor so that i don't need a controller and can just use the arduino PWM to drive it.
All nice but the boards and the components take time to get here and we are near christams so i'm expecting all the stuff to be here next year, so i'm making a temporary board with perf-board and what little i have here right now, the only problem is the big 15+ A capable mosfet that needs some circuitry to drive, using a single BJT inverts the control logic but also makes it so that if something fails the heater is on 100% and i'm not expecting to check the enclosure often so it's a big safety issue. some kind anon suggested to use two and make a bjt "buffer" to drive it, i found the circuit above and tested it but while in the forum i found it they said that is should work fine (and indeed it does) it still inverts logic, other push-pull circuits i found won't work with the 5V signal driving 12v

>>1977655
What temp ranges?

>>1977655
I get this is /diy/ but what's the reasoning behind building your own PID controller instead of buying one? Cost?

>>1977667
PID are incredibly simple to make and code (if you are going digital). Not OP btw

>>1977664
nothing too serious, it's in my garage but with no heating in there during winter i still go down to 10°C there at night and i need at least 20+ °C

>>1977672
Why are you not using the transistor as a heating element then? you would not need switching.
>arduino pwm
>low pass filter
>transistor

>>1977667
a PID controller it's more than 30€, i can make 5 for 10€ and i already have people who want the other 4 so it's a nice little weekend project and i can even come out of it with beer money

>>1977674
getting trannies to put out 100W without exceeding their junction rating can be a pain. easier to work with a cartridge heater or whatever he's got.

>>1977681
I only read the part of the post in which he replied to me. I thought it was sub-100W because
>small enclosure
Disregard this OP
>>1977674

>>1977681
??? testing

bjt , transistors , mosfet , jfet , igbt , triode

>>1977707
>passing 100 W =/= dissipating 100 W

>>1977499
I know, but a perfboard circuit is more delicate and looks worse. Which happens to matter in this instance.

>>1977756
you need to cake your perf boards with nail polish after they are done

>>1977757
I cake all of my boards with jizz.

>>1977776
put little rgb led hats on those fungi and submit it to the guggenheim as modern art.

>>1977486
Wait actually, UV-curable solder mask might be a better etch resist than nail polish, since I have near infinite working time until I put it under the sun, and can just scrape off the bits where I need a solder pad and leave the traces covered. I'll have to test that.

>>1977776
hotgluing pcb waifus when

Pic related is a Cascode amplifier, which you can get by coupling a common emitter with a common base. Unless I'm mistaken, once the common emitter fixes the bias current ICQ through VCC and R1, R2, R3, then Q2 also gets biased at the same ICQ.
Then, do R1, R2, and R3 not affect the common base? Can't it occur that the combination of those 3 resistances bias Q2 with a current different than the ICQ fixed by the common emitter? Basically, the question is, who sets the bias current for Q2? the common emitter with Q1, or the voltage divider formed at the base of Q2? Or is there like a feedback loop that stabilizes things that I'm not seeing. Thanks for the help.

>>1977573
uhhh, everyone knows that the output is only proportional to the turns ratio for an ideal transformer. It's stated in literally every circuits 101 textbook.
And of course a phone charger transformer won't work on 60Hz. Ferrite cores are designed for high frequency DC-DC converters. Not transforming sinusoidal mains AC. You need laminated iron cores for that. Ferrite saturates too easily at 60Hz and you need many many turns to keep the peak flux density down, this leads to large resistive losses in the wiring. Again, anyone with basic knowledge of circuits and magnetics knows this.
As far as the LED goes, again, every knows components have a power rating. P=VI for DC circuits. Since the LED has a more or less fixed forward voltage (in practice it varies slightly according to the forward current and temperature) the power is primarily dictated by the forward current. A capacitor has a very low internal resistance meaning it can source a lot of current. When forward biased an LED also has a low internal resistance meaning it can't sink a lot of current. There's a reason why we use resistors in series with them normally. Even though a capacitor can't store much energy it can store enough to exceed the peak forward current rating enough to damage it. I'm sure there's some capacitance low enough that even if charged to 60V or more it will not blow out an LED simply because the peak current delivered won't be enough to exceed the LED's rating which is typically specified over some time interval. (eg. 150mA for 10us or whatever).

>go to pinterest and marvel at all the circuit diagrams. make a few random simple ones. ask yourself why the fuck half of them dont work. why are there comments to the effect of "+1 post" and "amazing". why validate circuits that dont function? refer to bottom line
Cause people are dumb. Like you.

>>1977965
>it can't sink a lot of current
it CAN sink a lot of current
Typo

>>1977965
cringe post, probably paid for by the electron jews to hide the truth

>>1977965
actually 1) frequency determines amplification of the input with the number of secondary windings but primary can be anything from 1 to 50 as long as the current can pass through which is why i said 60 hz because at that low of a frequency the skin effect wont fuck the proof. only in bucking will the primary vs secondary matter or if your oscillator is affected by the inductance of the primary

why ? how? the primary induces a voltage on the secondary when the magnetic field it creates runs through the wire. this can also be from the core due to the primary depending on how you wound it. but each pulse puts electrons in the secondary. if a electron cluster deposited is hit by another pulse its counted as in series so its additive. thats why more wire on the secondary helps for boosting . the transformer doesnt know how many windings are on the primary just the strength of the field imposed on the secondary. thats why bucking you need more wire. stringer field. nobody bucks at 200 khz or higher but you might boost at that. skin effect makes it to hard to get enough current through the wire on the primary. your input at 10 amps means jack shit

2) ferite works at any range iron cores do not just high frequency. every one spreads the lie that ferrite is for high frequency and steel is for low. but to this i submit the iron powder toroid cores. sorporate data sheets you can look up for different grades of iron powder show hundreds of kilohertz to mhz range operation. its particulate ferromagnetic oxides. thickness of material determines max frequency. its counted as dust. lots of dust squished together but dust all the same. and by the same token ferite is feromagnetic oxides combines with ceramic. go get a compass and a 9 volt batter and a ferrite inductor. put them together and watch the dc current make a magnetic field that affects the compass

the charger transformer is bad because of saturation of the core being far more likely at 60 hz

Well, we are at the end with my project, i did manage to make the bjt buffer to keep the direct logic on my board, tested the transistor part before soldering it with a little load and it works and the "logic and signal" part worked too when i tested before soldering, tomorrow i'll just connect the real deal and see if it explodes on my face! i did make some obscenely big 12V and GND connections using a lot of cables to make sure the 10A don't damage the board or just heat solder too much

>>1977971
It wasn't quite right to say outright that a ferrite won't work at 60Hz. It's not optimized for 60Hz, regardless of whether it's a buck, boost, or even just 1:1. You'll have high losses always.

Regardless, you're right. Transformer design is complicated. More complex than Vout = Vin*(Np/Ns) as it's often oversimplified but I didn't think your original post presented that well. Hell, I don't really think the post I'm responding to presents it well either, it very nearly reads like word salad and is full of grammatical errors. I'll give you the benefit of the doubt and assume you're either on a phone that's auto-correcting every other word or you're ESL.

Wait, maybe headphones will be just fine with only an LM358

>>1974042
I have to use a mobile hotspot (4g LTE) for internet atm. Using a coolpad surf. It only operates if the battery is inserted. Any idea if this type of thing is likely controlled by software? Or potentially way to hack it with solder to think it has a battery in it when connected to the wall?

>>1978025
What connections does the battery have? Does it have just passive pins aside form power and ground (e.g. thermistor) or does the battery have some smart chip that communicates to the power management IC? If it's dumb then you can probably just spoof it by slapping a resistor or three on the connections. Also are you using default firmware? Non hardware-specific firmware is more likely to not care about battery presence.

Look at the spec sheet of both the battery and the power management IC. Which looks like it has a half-removed SMT component next to it.

>>1978022
LM4556

>>1978109
Don't look that good to be honest

might have a spare opa2134 lying about though

>>1977825
>Unless I'm mistaken, once the common emitter fixes the bias current ICQ through VCC and R1, R2, R3
I believe that's mistaken.
R1, R2, and R3 are chosen so their voltage drops are unaffected by the current draw of the bases - they are a master reference, so to speak
>who sets the bias current for Q2?
Using KVL and assuming the voltage drops for R1-3 are constant: The voltage drop across R3 minus 0.7V will be the voltage across Q1's Re. 0.7V/Re will give you the emitter current Ie, and thus the collector current Ic.
Assuming you biased the common base properly, this should be the same for Q2's Ie and Ic, along with the current through Rc. If they are not the same, that means your amplifier is saturated on or off.

Keep in mind, the voltage drop from collector to base (Vcb) will stretch in order to satisfy KVL. It can be 0V, 5V, 10V, anything it needs to be, as long as you give it enough headroom (V) to swing

>>1977496
>525 MW max active power
>Megawatts

Pic related broke. Specifically, the EU plug piece below broke (on the non-visible face).
Rather than buy a new charger (getting jewed 40-50€ for a charger to an ancient shitty netbook), I'd rather get just the piece, if this was at all possible.
Is this anything standard you recognize?

>>1978233
Damn euro plugs need a weight loss program

>>1978228
improper capitalisation is a sin

>>1978243
It lost weight already. The plastic holding the 2 rods did pretty much break into tiny bits.
There's two options... either we figure out whether this plug adapter piece is standard somewhat (and grab one or a few), or I just solder some wire with a separate plug, which is what I'll likely end up doing.

>>1978195
>might have a spare opa2134 lying about though
Shit, I've got two of them. Plus the one I know is in a project elsewhere, that's like 30usd from the local scumbags where I'd have bought them from, which is disappointing.

I should probably stock up my collection with better op-amps than LM358s and LM324s, I've also got some LF353s for low-noise stuff so I'll probably want higher current output and just generally more modern. Rail-to-rail isn't necessary, low quiescent current isn't either but could be nice. Don't suppose anyone here has particular favourites?

>>1978233
>getting jewed 40-50€ for a charger to an ancient shitty netbook

you got thrift-stores where you live? i probably bought a dozen 19-21V @ 2-6A chargers for an average cost of around $3.

>>1978270
Sadly no. Maybe if I went to the city, but COVID restrictions don't allow unjustified movement.

>>1978277
Oof, must suck being a euro

>>1978277
>unjustified movement
What are you talking about, you are just going to the pharmacy to get some medicaments for your grandma or something, because your puny little village pharmacy doesn't have the drug that she needs.
When we were in lockdown back in march almost everyone bent the rules a little, learn how to be more sly or something.

Do you reckon we'll see laser diodes with somewhat comparable cutting power to CO2 tubes in the near future?

what the fuck is the point of this

>>1978270
>paying for 19V bricks
They are free. On trash day it takes only 3 minutes to spot one in the street.
Thank god for making niggers separate e-waste from general waste.

>>1978389
every signal line gets its own ground for noise cancelling (look up differential input) reasons

>>1974042
Is it me or are TL431s becoming less common?
It used to be that every little switching power supply I took apart had the ubiquitous TL431 + optoisolator to regulate the output voltage, which was very convenient because they could be easily trimmed by replacing one resistor.
Now they all seem to do their regulation from the high-side, not closing the loop from the low-side at all.
Sad to see the noble 431 go the way of the 555.

>>1978420
Fuck the 555

>>1978317
no

>>1978422
Why do you hate 555?

>>1978407
thats gay, i'm just going to connect them all together because i'm lazy and not once in me whoe life have a run separate grounds for spoiled signal circuits and had any problems

>>1978389
To provide return path for signals and reduce crosstalk, especially useful for longer cables so there is ground-signal-ground-signal-ground etc

>>1978463
Do what you want nobody cares

Can i use pic related as an electric guitar pickup (for a single guitar string)? It has two coils inside right? Can I just connect one and leave the other unconnected or will that create noise?

I was looking at this schematic for an envelope generator and while most of it looks pretty straightforward (comparator feeding a signal buffer), I've not seen the potentiometer/diode combination in the middle before and I'm not sure how it works. Is there a particular name for this sort of technique so I can read up on it?


>>1978528
Am I right in thinking that a pickup detects the string moving through it's magnetic field? You could pass a strong enough current through it and measure the current for any fluctuations (i.e. field interaction). As for the second coil, so long as it doesn't move (in relation to the first coil) then it shouldn't be picked up (although it would probably be a good idea to ground it anyway).

Can someone help me check if I got the right answer?
For this, I got R_thevenin = 25 ohms.
My V_thevenin is -2.5 volts.
My I_norton is -0.1 amperes.
Dividing V and I, I got 25 but some of my friends are telling me its 50 and I feel like it might've been a calculation error on their end

>>1978538
>You could pass a strong enough current through it

LOL. "Hey man, why does it feel like this guitar is trying to electrocute me?"

>>1974042
How do I build a functional Pierce generator on a bread board? I want to generate a 3.58 MHz signal. Scheme picrel. I tried but the best I got was some kind of periodic signal though completely fucked. The resistor and capacitor values were picked more or less but they should work for that frequency. What did I miss?

>>1978541
Magnetic field strength is proportionate to current and inversely proportionate to the distance of the point from the magnet. The math isn't extremely complicated but you'll still want to figure out the values that you want since the coils are electromagnets (don't most pickups use permanent magnets?)

>>1978389
Also note that if you use a ribbon cable, the wires will alternate signal-ground-signal which reduces crosstalk.

>>1978540
Thevenin is 50Ω, -2.5v. Norton is 50Ω, -50mA.

You have i=(5-2v)/2000 and i_in=v/25+20i. Substituting the first into the second gives i_in=(2v+5)/100 = v/50+0.05 (Norton) = (v+2.5)/50 (Thevenin).

>>1978548
>don't most pickups use permanent magnets
in videos I've watched of DIY pickups they use neodymium magnets. Also, I haven't seen anyone passing a current along it at all (as mentioned by >>1978538 )
but rather, the string itself just produces enough through vibrating that it is able to detect the fluctuations from nothing.

hopefully pic related does a good job of explaining.
As a side note, I haven't been able to find an actually decent schematic of this, they are all dumbed down bullshit for guitar people instead of electronics people, and use little colored icons of the pickup and potentiometers and wires and such. If someone knows how I can find a more professional schematic I would appreciate that.

>>1978564
God damn it. Thank you so much anon, we were debating for like 30 minutes and we finally got some outside input. Looks like R_th = 50 Ohms was the correct one after all

>>1978538
It's simple anon, just think about it. Start at the output of opamp A, When it's above the voltage on the cap on opamp B's input (+ .6v for the diode) the upper pot and diode conducts, when it's below (plus a -.6v), the bottom pot and diode conducts. Each of these currents serve to either charge or discharge the cap on the second opamp which is in a basic follower (buffer) configuration. This means opamp B holds the voltage it's following for an RC time constant determined by,
>The cap's capacitance
>Whether the cap is charging or discharging, and
> What the resistance dialed into the conducting pot is.
Given what you know about an envelope follower, this should make sense. The cap holds the maximum voltage on the follower for a bit. The time it takes to charge or discharge is determined by the respective pots. That is to say, the time it takes for the envelope follower to rise or fall is determined by those pots.

>>1978538
>>1978601
And let me clarify a bit about the .6v drop in either direction. That's just a physical property of the diodes. But it actually helps the circuit too when you think about it. It basically adds a +/- .6v threshhold on the input signal that prevents small noise and fluctuations from affecting the follower. A voltage change on the input signal must have a magnitude greater than .6v to modify the envelope.

>>1978446
not him, but: high quiescent current, high output dropout, impossible to do pwm without also doing pwm at the same time or vice-versa, extremely bad pinout

>>1978528
A typical pickup is a combination of a permanent magnet and a coil. The moving ferromagnetic string distorts the magnetic field of the permanent magnet, and these distortions are picked up by the coil. They're supposed to have particularly open magnetic cores such that they can detect distortions in a magnetic field a few cm away, but the transformer you posted has a pretty closed core, so you'd want to break off the outer parts and hope the whole thing doesn't crumble apart on you.
Since it has two coils, you could use one to put a DC current through to make a magnetic field, and use the other to pick up the distortions in it. Using just one coil (with a constant-current source or similar) and measuring its own fluctuations will possibly work, but for that I'd just use cheap open-core THT inductors.

Still, just winding 50+ turns of wire around a neodymium magnet is probably going to work a lot better, since modern permanent magnets have pretty strong magnetic fields compared to what one of those inductors could put out with a reasonable amount of current.

>>1978538
It's not a perfect envelope follower, if it were they'd be using ideal diodes with feedback. Instead, they're doing current limiting on both the attack and decay, with the balance between them changing the output waveform. Personally I'd have used a smaller pot for attack than decay, considering if decay was faster than attack you'd not get anything much.

I prefer synchronous envelope followers though. They have three ideal envelope followers, and a diode-based selector to output the highest value of the three, then you run a clock to ground out / reset the storage capacitors on the three sample+hold circuits sequentially. That way you get a very accurate envelope following without needing to compromise with the decay rate.

>>1978613
>impossible to do pwm without also doing pwm at the same time or vice-versa,

wat!

i feel like theres a market for electrial engineering related subjects on youtube done by a white man that can speak english.

seriously struggle to understand all these pajeets

>>1978621
That is to say, feeding a signal into the CV input does both PWM and FM at the same time

>>1978601
I see. I forgot to consider that in an AC circuit the capacitor would have to discharge both ways. The .6V on the diodes is also interesting; I would have thought the voltage drop would be negligible but considering the circuit is using a +-12V supply I'd say it's rather substantial. I'll have to remember to consider it when thinking of modifying the generator part.

>>1978546
>breaboard
Is vcc properly decoupled?
What inverter part number?
Where output goes off to?

>>1978633
>feeding a signal into the CV input

irrelephant coz practically nobody does PWM in that way.

Redirected from >>>/sci/

I took Electrical Circuit Analysis 1 + 2 in university, and remember learning about RLC circuits, impedance/load balance (when a circuit is inefficient due to being to reactive or inductive or whatever), how to solve Kirchoff (sp?) loops for voltage and current and what not. I still have a very good intuition and understanding of those, and I wanted to continue on with some self education for circuitry and whatnot. What would be next in the natural progression of the topic? The further along you can forecast topics, the happier you will make me.

GIF epilepsy warning.

>>1978757
>What would be next in the natural progression of the topic?

the future is all digital. forget everything you've learned. buy and arduino UNO and start reading at https://www.arduino.cc/

>>1978757
>What would be next in the natural progression of the topic?

the future is all digital. forget everything you've learned. buy and arduino UNO and start reading at https://www.arduino.cc/

in under three months, you should be flashing an LED and calling yourself the 'Maker Kid'

>>1978757
honestly your at a position you're able to branch out into specific topics.
While you can do whatever you want, here are my recommendations.
>deep dive into microcontrollers.
Not arduinos, but straight microcontrollers. The avr microcontrollers are good noobie 8 bit micros. The main arduino is based on the atmega328pu. This is a good starter chip. But buy the actual micro and learn about avr-gcc and avrdude and stuff. You'll need a programmer to program them. You can use an arduino or you can buy a dedicated programmer. They're only $15 or so, so it's not bad. The pic programmers are fucking highway robbery, at least back in my day.
>Digital circuits and Computer Architecture
I don't know what your courses covered, but digital design is often its own course. Computer architecture is typically the next course after this. Learn about things like finite state machines, karnaugh maps, etc... The book "Digital Design and Computer Architecture" by Harris and Harris is a good text for someone in your situation. Digital circuits tend to drift directly into computer architecture, so that text will cover both bases.
>rf electronics
radio shit is pretty cool. There are lots of different parts to this. You can buy an SDR and use computer programs to analyze the data. You can do some cool shit like unencrypted police radio.

>>1978538
It's similar to the saw -> triangle convertor in the MS-20

You boys on the straight and narrow?

What a long and tiresome day of TAOE.

>>1978871
Several years ago the EE department at my uni cleaned out a storeroom or something and they had these big carts full of old engineering books that you could take. I had a locker nearby, so I just filled it with a bunch of textbooks. They were in really good condition too. Haven't read a single one, but it assuaged my severe textbook AND retro-engineering autism for a bit.

>>1978884
You'll like this then

What is 58 - nickelodeon?

>>1978917
>The channel's name comes from the first five-cent movie theaters called nickelodeons.
>Nickelodeons usually showed films about ten to fifteen minutes in length, and in a variety of styles and subjects, such as short narratives, "scenics" (views of the world from moving trains), "actualities" (precursors of later documentary films), illustrated songs, local or touring song and dance acts, comedies, melodramas, problem plays, stop action sequences, sporting events and other features which allowed them to compete with vaudeville houses.
https://en.wikipedia.org/wiki/Nickelodeon_(movie_theater)
Popular 1905-1913

>>1978696
Sure, maybe if you want to do open-loop PWM. But if you’re using it as a part of a feedback loop of a diy switching controller or something along those lines, you need to use the signal out of your error amplifier G*(Vref - V) to vary the duty cycle as a part of a feedback loop. But for a switching controller it doesn’t really matter if your frequency is varying unless you’re doing some sort of frequency specific output or EMI filtration. In fact, the modulation might happen to be better for switching controllers.

What matters more is if you’re trying to make an FM signal of some sort but your duty-cycle isn’t staying at 50%. The 555 presents one of the very easiest ways to have a VCO, and it just so happens to be really bad at it.

>>1978757
Learn to use complex numbers to analyse circuits with reactances and resistances, and hence how to analyse filters. Op-amps too. Even if you’re not getting into analog electronics, it’s helpful to know this as amplifier and filter circuits are useful all over the place. If you want to dive deeper, then nodal/mesh analysis is the way to go. Learning filters and amplifiers is necessary for RF, though going specific into discrete amplifier topologies is a bit esoteric as a lot of the time there’s already an IC to do that sort of function, so don’t get too worked up trying to learn transistor biasing techniques or obscure oscillator topologies.

>>1974042
I'm doing babby's first soldering job
Keep getting solder in the holes
What do? I don't have anything to remove it

>>1978944
Reflow the unwanted solder and blow it out of the hole through a straw. You could possibly also have success by reflowing it and sticking a wire in, taking it out, cleaning the solder off, and repeating. I've also heard of success by reflowing the unwanted solder and banging the whole board on a table. To avoid this, I'd fill all the component slots initially and tape them in place. Might also be decent to cover the holes with kapton tape, assuming you have any.

>>1978757
>complex numbers
>ac power
>fourier and laplace
>basic filters
>basic electronics

How do I get into electronics design? I have always disliked the idea of just taking a schematic and doing everything there, but everytime I try to design something, there is a lot of stuff to consider to the point that it is a bit overwhelming.

>>1978921
That's really fucking interesting.

>>1978964
How do you even apply Laplace in electronics? I know about Fourier though I see no real need to understand the mathematics behind it as any scope with FFT can convert time domain to frequency domain. It's definitely useful to understand how signals behave in the frequency domain and it may be useful to know about like the different windows and stuff for DFT but I can't think of any circumstance where you'd actually need to calculate it by hand outside of a classroom.

I'm not even sure how Laplace factors into anything at all though I've been told it's important. In my Diff eq. class we mostly did problems and looked up the table of common solutions for the Laplace and inverse Laplace transform in the book and attempted to calculate it only if none of those solutions fit which didn't always work. I took that class like 6 years ago and I still have no idea how it fits into electronics.

>>1978965
It's really just about accumulating knowledge. Any circuit you design is going to be made out of a few or a few dozen subcircuits, each of which is going to be a variant of some relatively conventional design already in existence. When you start a project, you should pick one where you know most of its subcircuits, but still have to learn one or two. For a beginner, you should make a circuit with only one subcircuit/block in it, like a single stage microphone preamp or LED-flashing oscillator, just to cement your knowledge. Then branch out turning that preamp into a headphone amplifier and then into guitar effects, or turning that oscillator into a switching converter and then into a geiger counter. That sort of thing. So you always have confidence in part of your circuit, but are also always learning something.

Also ensure you have a good way of verifying designs, be it a simulator like LTSpice, or a breadboard and a good array of parts. Sim or not, it's a good idea to use software to lay out your circuits. And don't be afraid of copying circuits or subcircuits, so long as you understand how they work. There's no getting around it. Using a circuit without understanding it is ill advised, it just doesn't teach you anything and you can misunderstand it and end up with a faulty final product.

>>1977486
CIRCUIT REVISION
NO POWER AMPLIFIER NEEDED
UNBUFFERED GROUND REFERENCE
NO JUMPERS AT ALL
WELCOME TO THE ZONE

>>1978957
The best way I figured out to do it was to actually position the component legs and push them trough while heating the trough hole, nothing else really worked since these holes might as well be microscopic compared to the size of my iron tip

It's taken awhile but it works
Didn't work the first time, the big dip package wasn't seated right

But after that it all works
It talks creepily enough

>>1979061
It all looks pretty good except for that LED, though I know that sort can be a pain. Your resistor alignment could do with some work, you should be putting both legs through and bending them so they don't fall back out.
No shortage of flux.

post tip

>>1978971
The Laplace transform is the more general version of the Fourier transform. The Fourier transform is just the Laplace transform with s=jω, i.e. it describes how the system responds to purely periodic signals. Any linear time-invariant system can be described by a transfer function in s; the behaviour of the system is equivalent to convolution with the inverse Laplace transform of the transfer function.

It's most useful in analysing the behaviour of a closed feedback loop. If the Laplace transform has poles in the right half plane (Re(s)>0) it will be unstable, i.e. a pole at σ+jω with σ>0 implies oscillation at f=2πω.

>>1978771
>Most-Popular-Development-Boreds.jpg
Bored indeed. So bored I have to note this pic is bs.
No stm32 blue/black pill, no msp430 lauchpad.
Onion? Particle Argon? Tessel? Seriously?
Pic seems to just be trying to promote these unknown boards.

Ok guise, do any of you have any info what TO-220, TO-247, ISOTOP, or other MOSFET packages current rating?

>>1979076

>>1974042
Has anyone here had any experience with Genesys logic?
Even their name sounds chinky..
Just bought a memory card reader with GL3224 inside. Is it gonna kill my memory cards?

>>1979084
Current rating depends on series resistance. This resistance "Rds_on" varies from MOSFET to MOSFET, varies by temperature (which varies by power so you've got some circular bullshit to work through), and also varies by the voltage at the gate, V_gs. So, just read the datasheet. The IRF840 for example has thermal data (1°C/W to case, 62.5°C/W to ambient with no heat-sinking) that you can use to calculate the temperature of the transistor for a given power dissipation, and also has a graph of acceptable current ratings for certain temperatures. Pic related, top right.

The current can also have peaks at much more than the continuous rating so long as the pulses are sufficiently short, since it effectively decreases the thermal resistance of the package. But only to a certain extent, as the bond wires and silicon itself also have thermal limits. This information is also in the datasheet, pic related, bottom.

>>1979092
yuck

>>1979084
read the datasheet and find out

>>1974086
>TL431
Ayy am working on an "old" circuit at work where I need to replace one of these with a 1.24V ref version (TL432?)

>>1978646
Vcc seemed to be ok
Inverter is NC7SZ04 it's quick so it should work.
I am doing an analog video filter based on a Philips IC. And that chip to function properly needs 3.58 MHz NTSC sub-carrier frequency. So the output from the generator goes to the IC.

>>1974042
I want to make a laser pointer arm that will point to a star constellation given input commands from a phone.

Is there an open database/api for star locations?

>>1979268
Not him, but what kind of filter are you making?

>>1979291

It's a video filter. Takes porn images and makes girls look underage. A NYT reporter commissioned the project. Some prominent Republican lawmakers have also shown an interest, including a sitting US President i'm not allowed to name.

>>1979291
I am making a comb filter for composite video
>>1979335
retard

>>1979335
Take your /pol/ bullshit and fuck off

Can someone break down into retard terms what the Fourier transform is? FFT? What is it used for? Examples?
I've tried to look it up, but everything is explained in high-level details and with zero applied examples for what it can be used for.

What's the point in quality cables for musical instruments if then the signal is passing thru wiring like this? Especially the thin wire on the lower part of the 3PDT where it looks like he's used a resistor leg to bridge from one pad to another?

>>1979371
ferro magnetic metalic box.

>>1979377
The enclosure? I get how that would protect it from interferences but the wire gauge...

>>1979378
I do not understand what you are talking about

>>1979370
detail what you want to understand it for and I can draw up an explanation

>>1979383
In short the fourier transform shows the frequency components that make up the signal. (If you sum sine waves with those frequencies the result is the original signal). FFT is just a way to compute the discrete fourier transform (discrete signals) faster.
>what is it used for
Welp, lots of things. Your inner year works kinda like that, it has lots of hairs of diferent sizes that are "tuned" to a specific frequency. If you add how much each one of those hairs was triggered then you have your sound.

>>1979387
this is retard explanations, it is used in more than that and has other meanings btw

>>1979371
because you live in a world of lies like the bose super audio rf choke. yes its just wires. no radioactive isotopes despite 2 court cases that the plaintiff was awarded money

its like how long does it take a capacitor to charge? according to all the online calculators for capacitor charge time current is never a factor. but you know thats a lie so you check and check for a working one and find that capacitor smoothing calculator factors in time and you work backwards to find the capacitance you are using by adjusting time step increment and you get a correct answer not one in which volt amp is assumed because nobody is using 250 v 250 a supply so stop being a faggot google and disregard the nonsense but no google is so much a twink t lured yandex and duck duck go and bing into their web of lies

its like alldatasheet not having all datasheets. where does it end? for you that little box of wires and a question. why should i pay more?

>>1979390
based schizo poster

>>1979390
Hi there. I work for the CIA and I'm always watching you from the shadows.
Always.
Stay safe.

>>1979360
neat
>>1979335
>"orange man bad"-posting in /ohm/ for no reason
You'll never be a woman, you tranny fuck. I may be a homosexual, but at least I don't look like an abomination. Everyone hates you, even other members of the "LGBT community".

>>1979390
wow that's fascinating

>>1979398
The joke was he was implying he was paid by the democratic party to create something which would falsely implicate prominent republicans of having child porn. It wasn't a good joke but you would have gotten it if you weren't retard whose brain has been addled by too much exposure to /pol/.

>>1979371
The box is shielding.
That 'resistor leg' wire can handle more power that you may think. It's probably for a signal anyhow, and not high power to drive a speaker.
Once you exit that box, you need good wire to transmit the audio over much longer distance and not have much loss, while rejecting interference.
To be fair, that is a shitty wiring job though.

>>1979383
>detail what you want to understand it for and I can draw up an explanation
But I don't understand what its used for. I'm looking into DSP for audio and FFT gets thrown around a lot.

>>1979387
That still makes little sense. Is it a time based equation that gives outputs for a set time frame?

platter stopped spinning on my turntable. seems rare for the DC motor to burn out suddently. these old turntables can last for decades
theres no voltages listed on the schematic, where can i put the MM to test for power to the motor?

>>1979409
It's a convolution transform. F{g*h}=F{g}F{h} where F{...} indicates the Fourier transform and * indicates circular convolution. Using the FFT is far more efficient than calculating convolution directly.

But realistically, you aren't going to get a useful answer in the space of a 4chan post. Actually, an entire thread dedicated to it would hit the post limit before explaining half of it. If you get a decent book on signal processing theory, it's going to revolve around the Fourier transform.

>>1979418
>If you get a decent book on signal processing theory, it's going to revolve around the Fourier transform.
Cool, and recommendations?

>>1979409
> Is it a time based equation that gives outputs for a set time frame?
The FFT is a fast way to compute a DFT. A DFT of size N is literally just a NxN matrix which transforms an array of N complex values to another array of N complex values. If the original values are real, you still get N complex values but they have conjugate symmetry (y[N-n]=y[n]*).

Why is this useful? Because you can perform discrete convolution efficiently:
z[i] = sum[j=0..n-1](x[j]*y[i-j])
becomes
Z[i]=X[i]*Y[i]
where X,Y,Z are the DFTs of x,y,z respectively.

Performing direct convolution of n samples requires n^2 multiplications (every x with every y), whereas the FFT only requires O(n*log2(n)) operations and multiplication of the transforms only requires n multiplications.

>>1979406
Last I checked jokes were usually funny

>>1979427
knock knock

>>1979370
>everything is explained in high-level details and with zero applied examples
>>1979423

Never become a teacher.

>>1979413
>where can i put the MM to test for power to the motor?

across the motor windings is usually a good place.

by process of elimination, it would seem the 4 coils on the RHS of the drawing belong to the motor, which could be confirmed by seeing 6 or 8 wires on the motor itself. but the transistors driving those coils are fed by 2 mystery parts named HG, so it's impossible to say what kind of voltages or waveforms are being sent to the coils. having 4 coils implies it's a stepper motor, so a voltmeter is not enough to test it, you'd need a scope.

anyway, you have a test point, TP3, so probe that for fun.

>>1979370
Fourier converts an amplitude signal plotted against time to an amplitude signal plotted against frequency.
FFT essentially takes an oscilloscope and turns it into a spectrum analyzer. It's often useful to see the spectral content of a signal. It can give you a lot of information about a signal which may not be easy to see in the time domain. One example might be audio distortion. If you feed in a 1kHz sine wave with maybe 1% distortion that will be audible however if you look at the signal on a scope you will barely see it. It might look like a slight broadening of the peak of the sine wave but it's very hard to perceive a difference. In the frequency domain that distortion is easily visible as you also see smaller signal peaks at integer multiples of the fundamental frequency so 2, 3, 4 kHz, etc. This is information you cannot get by only looking at a time domain signal.

>>1979456
>HG
cant find it anywhere in the SM but it looks like they are the 2 sets of 4 clusters next to the motor here
>TP3, so probe that for fun
shame this service manual i have doesnt have all the pages, it doesnt say what the scope should be set at or what i should be expecting to see.

>>1979464
oppsite side shows that the HG leads are hidden under the motor plate

>>1979465

possibly HG are hall-effect sensors. some kind of feedback thingy that lets motor control its own speed.

>>1979429
frig off ricky
https://youtu.be/je-M675ZTK4

>>1979290
Nice idea, though the laser will be invisible without a dome to shine it on or some sort of fog/smoke/haze to shine through. From google and stackexchange, I got two main results, Gaia and Hipparcos.

>>1979370
digital signal processing is used all over the place, from radio demodulation to audio processing to filtering sensor data
say, if you wanted to filter out everything past 10kHz, you'd take the FFT, and set every value with a frequency above 10kHz to 0, and take the inverse FFT, and you have a filtered signal. Doing that kind of brick-wall filter with analog filters would require quite a lot of components.

>>1979409
>Is it a time based equation that gives outputs for a set time frame
Theoretically, an ideal fourier transform is over an arbitrarily large amount of time. Naturally, we can't do this IRL. The fast fourier transform takes a data set spanning N samples over T seconds, where N/T is the sample rate. The longer the sample time measured, the lower the frequencies you can detect with it. Say, if I measured for 10s with a sample rate of 100S/s, that's 1000 samples. The maximum frequency I'd be able to correctly discern would be 50Hz (as per Nyquist's sampling theorem) and the lowest would be 0.1Hz. There will also be a DC component, which isn't usually useful. The resolution would be 0.1Hz between each data point, so when looking at the data with a log-log plot like you might with a bode plot, the low frequencies will be much coarser than the high frequencies.

If you're doing a live FFT, you probably want the data to reach the other end with minimal delay, so tuning that time T is somewhat important. You also need to store every single data point of N in memory, which can be quite a task for lower end microprocessors. If I recall correctly, MP3 audio stores a bunch of small packets of FFT'd waveform (i.e. small T), each of which has to be buffered by the digital audio player for inverse FFT conversion during playback.

>>1979409
FT is basically what spectrum analyzers do.
With DSP, you can do cool stuff like pitch shifting, mixing down radio signals, and some nifty image processing stuff

>>1979399
you know damn well a capacitor charge calculator should have current as a variable and they dont. 12 found through google none have it.

the smoothig cap calculator does. why? youtube fags mention the current as a variable. whats the point? to make me use a calculator? the assumption that the average america would just break down and buy something as opposed to use a normal calculator given the equation is stupid but actively the only answer you can derive from the situation

and who cares about the economy? nobody but glowies. i dont give 2 fucks if your doing ok. as long as i am everything is fine. thats how humans are. thats why america isnt communist. so it would have to be a well constructed farce with google as the linch pin holding the web of lies together . im sure some one uploaded a capacitor charging calculator with current as a variable. its not listed through any search engine however

>>1979578
>you know damn well a capacitor charge calculator should have current as a variable and they dont
It's simple, I = C*dV/dt. All those online calculators are derived from that. The trivial case is I = constant, because that means dV/dt = constant, not really any need for a calculator unless you're stupid. When you don't have a constant-current source, but rather a current limiting resistor, you no longer have a trivial case, and current is a dependant variable. Those calculators can't ask you to input a dependant variable, because that would make it an independant variable, and you'd be back on the trivial case again. The maximum current with a current limiting resistor is V/R, and it exponentially decays with the same time constant as the voltage does.

>smoothing cap calculator
I see where you're coming from here. There's two whole pages in my "textbook" (Transistor Electronics 10th edition by Gary E.J. Bold) dedicated to this. They quickly come to the conclusion that calculating the exponential decay of a resistive load is unsolvable analytically, so a compromise has to be made. Basically, you assume that the voltage after rectification and filtration is a sawtooth wave, being Vmax at the peak and Vmax - Vripple at the trough. The period of the wave is 1/f for a half-wave rectifier, or 1/(2f) for a full-wave rectifier. The slope of the sawtooth is set to the maximum slope of the actual exponential, or what you'd get for a constant current load instead of a resistive load; I/C. The simplification makes fora good worst-case scenario and covers what you'd expect with a linear voltage regulator rather well.
From this is derived two equations:
>V_ripple ≈ V_max / (R*C*f)
>V_ripple ≈ I_dc / (C*f)
Put a 2 in the denominator for a full-wave rectifier.

I can post the textbook pages if you want.

>>1979578
>you know damn well a capacitor charge calculator should have current as a variable and they dont
they do?

$$Q = \int_0^t i(t) dt$$

Even an exceedingly thin layer of UV-curable soldermask painted on works as a wonderful etch resist. And even thick layers are solidly cured after under an hour in the sun. I'll want to make the layer thick since that results in it being easier to see (thin layers are nearly transparent, should have gotten black or green instead of red), but the paint brush doesn't put that much on.

It doesn't come off with 10% acetone though, so I need to scratch it off. Which isn't much of an issue. I'll paint all the traces and SMD pads, cure it, etch it, and scratch the mask just off the pads, to have a nice solder mask on my PCB. Should make it nice and easy to solder, especially considering my traces are as wide as my pads. Might add some solder mask after etching to the bare fibreglass too, if I feel it's necessary.

>>1979421
literally any signals and systems or control theory book will have a intro into that

>>1979774
man my dsp and 'transforms' class sucked so much I pretty much learned Fourier/Laplace by myself, and everything you tell me related to the Z transform and its applications is probably going to blow my fucking mind.

>>1979413
ok new concern, what if the power transformer died? I get direct AC power to the light NL1 but nothing from the tranformer and beyond seems to work

i tried using my MM on the secondary leads and only got 2V. but that cant be right. NOWHERE in the schem does it list then in/out voltages or amps and the internet has no info on the GA6740 tranformer so i'm essentially clueless

>>1979878
are you measuring the secondary while it is disconnected from the rest of the circuit right?

>>1979881
i was hoping i wouldnt havent to desolder the transformer from the pcb, can i just detach the two wire lead here?

>>1979883
yes

>>1979899
disconnected
only reading 1.3V AC on both legs and 1.5VAC when switch is activated. is it fucked? anyway to replace a transformer when the specs are unknown?

>>1979878
Considering it's connected to an HZ24-2 24V zener diode, it's probably about 30-34VDC = 30-34Vpeak = 21-24Vrms, depending on how and where you measure it. Since it's also driving the motor H-bridge, it may be outputting a voltage significantly higher than that, but it almost certainly won't be below 20Vrms. The small 3k3 series resistor for the zener, a zener with pass transistor no less, suggests that the voltage isn't too much higher than what the zener requires.

>>1979926
Looks broken to me. I'd see if you can measure the current through the input too, or use some other way of telling which winding has a problem. I'm guessing it's a thermal fuse embedded in the windings, but it could be a wire breakage in which case you're shit outta luck.

You're measuring the AC voltage across the transformer secondary, right? Not measuring it to a third point or measuring in DC or some shit.

>>1979928
just to be sure
>mm ground to ground
>mm pos probe to either here or here set to VAC mode

ive heard of transformers going bad on turntables before but usually there is spec so you can replace it with another one.
>>1979927
thanks that gives me ballpark of expecting around 20 min and ideally 24

>>1979930
yeah if you are measuing 1.5v then something is probably wrong, it is barely enough to rectify. Also do a sanity check on your measurements if you are not used to dealing with transformers. (Measure another transformer that you know it is working or something similar). Luckly transformers are ok to replace

>>1979933
Also measure on the output conector thingie on your pic>>1979930, maybe there could some gunk or protection layer

>>1979935
same result, 1.5vac when switched
dont really have any other transformers to check, maybe an old latop power supply?
is it safe to touch the MM to the primary side with 120v coming in?

>>1979939
Yes, so long as it's rated to that voltage and you take care not to touch the wires.

>>1979941
thanks. its 2am so im turning in but ill be back tomorrow with more questions im sure thanks for the help. would love to fix this turntable instead of getting another one for $100+

>>1979944
Make sure to NEVER use the MM in CURRENT mode when measuring mains unless you know what you are doing. Just measure VOLTAGE.
>current mode = short circuit = bang and smoke
>voltage mode = open circuit = no smoke

>>1979930
>just to be sure
>>mm ground to ground
>>mm pos probe to either here or here set to VAC mode

so, you're measuring AC volts from ground to each leg of the secondary? if so, that's not right at all. you measure ACROSS the two secondary pins.

you can only do ground-reference measurements once you're past the rectifiers, and then you're measuring DC volts, not AC. if you're getting about 35Vdc across C201, then your power supply is likely A-OK.

>>1980025
Alright i did one probe on each pin of the secondary, power on, and got 0VAC across either pin
primary pins read 115VAC so it seems like something happened inside the transformer

>>1980297
Yes. Now unplug it and measure resistance across the two mains prongs

>>1980313
interesting. measured across the mains and got OL and measured the primary pins both directions and got OL

>>1980323
Inject 12VDC into the rectifier output. If that doesn't work step it up to 24VDC.

>>1980342
now this is where im stuck. this was going to be my next quetion do i need a variable AC supply or a dc generator to diagnose this? if so any suggestions?

>>1980356
or like this? https://www.amazon.com/Power-Adjustable-Switching-Desoldering-Electrostatic/dp/B07TVHQF5V/ref=sr_1_5?dchild=1&keywords=dc+power&qid=1608313864&sr=8-5

>>1980356
The line AC voltage is stepped down by the transformer and rectified to DC. Inject DC voltage at the output side of the rectifier to verify the turntable works normally. Then buy a replacement transformer and swap it out.

>>1980362
right, so i would inject here . i still need a DC supply to inject 12v-20v here. I dont think 8AA batteries would cut it.
going to have trouble finding another transformer with the same pin locations and specs
did a search for GA6740 or TKP0206 and nothing useful comes up

>>1980323
>measured across the mains and got OL
>measured the primary pins both directions and got OL
Because they're both connected to the same place, though at least it rules out a broken trace, which can happen due to how heavy a transformer is. That means your secondary is fine but your primary is open-circuit. Which is good, because that's where to expect a thermal fuse. Unwind any tape or cloth or whatever covering the winding(s) to see if there's a thermal fuse you can replace. Also inspect the binding points where the enamelled copper wire is tied to the transformer chassis for board mounting, it's rather possible that one of the copper wires broke off.

>>1980342
>>1980366
12V isn't going to work for shit, that's a 24V zener. Inject at least 25VDC.

>>1980366
>so i would inject here
Yes

Do you have an old laptop brick? They output ~19VDC. Use an inline fuse (2A-3A?) on the output from the PSU just in case.

>>1980384
>They output ~19VDC
won't do shit, that's a 24V zener

>>1980385
Okay I see that now.

>>1980383
>thermal fuse
okay lets give it a try. i just looked over the transformer and its solid so it will probably be on the bottom

>>1980396
he leakin
he need some milk
call a amberlamps

>>1980366
>going to have trouble finding another transformer with the same pin locations and specs

if the primary is open but the secondary has continuity, the most likely cause is a blown thermal fuse. those can be either bypassed or replaced.
there's a video on youtube showing how to do that, but the guy did it mostly wrong. he disassembled the entire transformer, which is not at all needed. you just have to carefully dig through the tape where the wires come out, until you find the thermal fuse.
pajeet video here: https://www.youtube.com/watch?v=Hum756Dh6xA

as for using a 19V dc power supply, there's a very good chance it'd work, coz the diff is only 20%.

>>1980404
alright i can see the fuse ends but not sure how to get to it

>>1980408

if the fuse is between middle pins on top, measure to make sure it's open, and if so, shorting those 2 pins should bypass the fuse.

>>1980408
It should slide out somehow, though it may be glued in place.

>>1980414
it was indeed open. bridging it gave me about 170ohms.
i will try to desolder it and pull it out

>>1980423
I'd still try to replace it, running it without a thermal fuse isn't the safest idea. Though replacing it with a PTC thermistor might be a better solution.

>>1980426
> isn't the safest idea

i wouldnt worry about it. the tiny wires will act like a thermal fuse, anyway, just one with a higher temp rating. and a proper replacement would have to be installed pressing up against the coils, or it wouldnt really work. how you gonna manage that w/o disassembly?

>>1980431
Just thermally glue it to the coils already visible in >>1980408

>>1980426
>>1980431
i cant get to it anyways so i will snip the lead and solder on on the bottom
any thermal particular fuse to get for this?

>>1980436
>any thermal particular fuse to get for this?

the temp should be marked on the unit.

when soldering or desoldering the terminals be super careful coz there's a tiny fragile wire attached there as well.

>>1980440
>tiny fragile wire attached there as well.
all is good they are unharmed.
there is no information on the transformer other than the model numbers,

>>1980446

the info is not on the xformer but on the fuse. if you dont see anything, assume 90-100 deg C.

>>1980452
thanks that gives me place to start. i cant see the fuse without major desconstruction >>1980436

>>1980455
something like this then?

>>1980455
something like this then?
https://www.amazon.com/Zephyr-Micro-Thermal-Non-Insulated-Connectors/dp/B077W92JT7/ref=sr_1_3?dchild=1&keywords=thermal%2Bfuse%2B212f&qid=1608318470&s=hi&sr=1-3&th=1

>>1980465

yeah, fine. if you get one that's shaped like a box, they're easier to isolate from the metal of the xformer. and should make better contact than a tube shape.

>>1980465
>>1980472

forgot to mention, when soldering thermal fuses, you gotta make sure to keep the body of the fuse under its rated temp or else it blows. use water or metal clips to suck heat away.

>>1980563
Not him, but would a PTC thermistor work instead? No clue how to size one for a given job though.

>>1980782

not really appropriate for a power supply as it has a cold resistance which would be in series with the xformer, thus reducing primary and secondary voltages. current fuses and thermal fuses make more sense in this situation.

>>1980782

not really appropriate for a power supply as it has a cold resistance which would be in series with the xformer, thus reducing primary and secondary voltages. current fuses and thermal fuses make more sense in this situation.

PTCs generally arent used to sense temperature. instead, they got hot from current flow, and then increase their resistance to counter any excess current. limiting inrush current is their main job.

>>1980836
>it has a cold resistance which would be in series with the xformer
They're used as resettable fuses for non thermal appliccations, I assume they have a nonlinear temperature/resistance curve like a varistor's voltage/resistance curve, or at least their positive feedback causes them to act like it.

>instead, they got hot from current flow, and then increase their resistance to counter any excess current. limiting inrush current is their main job.
I thought they got hot from inrush current, increased their voltage drop because of the increased resistance, and the positive feedback loop causes them to increase resistance until they're effectively open-circuit for a few seconds or minutes. Or at the very least have at least half the total voltage drop across them.
If their resistance increased enough to lower the inrush current, but not enough to stop the majority of current, I'd have thought they'd overheat within 10 seconds.

>>1980563
thanks for the heads up, im going to hunt for some clips now so i dont blow all the fuses trying to solder it on there

>>1979045
THE END IS NIGH

>>1980970
shit, there isn't enough sunlight to cure the traces

>>1980970
Is.... is... that nail polish.

>>1981077
It's UV-curing solder mask, it makes for a good etch resist. Can't be washed off with the solvents I have on hand though, so I'll just scratch it off the pads and leave it on the traces.

>>1980970

geez, dude, you said you wanted to make this look good, but you cant even cut the board in straight lines. there's lots of options for cutting straight lines, the cheapest being a $2 plexi scratching tool and a metal ruler.