From the power supply, etc board in a monitor. The lines in one area are connected to each other. Does it serve any purpose?

(previous post) https://www.reddit.com/r/AskElectronics/s/EiXXvfd9Ul

I’d like to build an Arduino project using multiple AC dimmer modules (RobotDyn AC dimmer module HL; 24A, 600V). I figured out most of the wiring, but these modules have a thin, red wire attached to them, labelled ‘N’, and I have no clue what it’s purpose is or where I should connect them. The thickness of the wire makes me think it should be connect to the low-voltage part of the circuit, but it’s placed at the high-voltage side of the module. Thanks in advance!

I don't know if this is the right subreddit for this but I found these old vacuum tubes in a box of old electronics I have no idea what kind of tubes are they and there are no visible markings on them

Hello all,

I was checking that LED driver. I saw that square wave line at the input. What can be the purpose of this wave?

In the first image, right cables comes from 220V AC, nect to it square line. In the second image it is MB6S, it is a bridge rectifier.

Thank you all.

Assume your favorite apocalypse scenario: You have the opportunity to bring you, your family and everything yall own to a safe place to live out your peaceful lives.

However you may only bring 10 ICs, and have whatever passive components you need.

What are you bringing?

I desoldered these transformers from random broken electronics now am wondering what to do. Any suggestions would be appreciated.

Hi everyone,

I’m trying to use a 3V/24V MOSFET relay (https://www.amazon.ca/-/fr/gp/aw/d/B0DFVPWR69?psc=1&ref=ppx_pop_mob_b_asin_title) to control a high-voltage mechanical relay (Bridea HTACC-02, 24V/240V). The goal is to turn an electric baseboard heater on and off.

I tested the mechanical relay manually by connecting the 24V control wire to the ground, and it works fine.

However, I can’t figure out how to properly connect it to the MOSFET relay. As shown in the picture, the MOSFET relay has two sets of +/- terminals, but the circuit I need to switch only has two wires. The input side of the MOSFET relay is connected to a Raspberry Pi Pico and seems to be working correctly.

Any help would be appreciated!

Hello, I'm really new to soldering and electronic repair in general. Like, I just finished this project yesterday new.

I picked up a project board on Amazon, just a simple little LED kit, and I cannot for the life of me understand why it's not receiving power.

I have two primary questions:

1. I'm 20 videos and 20 forums deep without an answer: Is there any way to do a cold test on this device to see if it's the DC jack that's the issue? If so could someone help walk me through it? I've done a couple basic tests but I'm not super familiar with a multimeter, especially in the application of small electronics
2. When i plug in the DC 3.5mm power cable it gives off quite a bit of heat a few seconds after use but no luck in terms of power. Would this indicate an issue with the jack? Or is that something I would find out with the above testing?

I'm adding some poorly-shot pictures because I genuinely don't know what I'm supposed to show. I also have a schematic of how everything flows together so if I need to add that please let me know.

I've also verified that all components are snug, there are no instances of solders that are touching eachother, and at the very least I've confirmed that the LED's work (finally found out how to do that with my multimeter) but that's all so far.

https://preview.redd.it/6atk3adxft9e1.jpg?width=1152&format=pjpg&auto=webp&s=fe87ba48177f43fa7d740459401a510b02061264

https://preview.redd.it/85fm7bdxft9e1.jpg?width=1152&format=pjpg&auto=webp&s=f6a425587820731c70f951ebbae329eacc480996

I have a prototype running on a €34 waveshare esp32-S3 capacitive touchscreen module which comes with a connector for stereo speakers.

I need to connect headphones so I'm using an external DAC module connected via GPIOs. The waveshare module comes with other sensors & RTC that I don't need.

I also noticed that the DAC chip on the waveshare circuit board is the same series as the one on my external DAC, so in theory it would be possible to micro-solder a headphone jack's left, right and ground wires onto 3 pins of the waveshare DAC. (Actually left and right would go to tiny resistors after the pins).

Would it be worth my while to design my own PCB and have it assembled with the specific components that I need? (Touch screen, sd card, DAC with headphone jack)? I see that i can source touchscreens for €10, ESP32s for around €4 and DAC and SD card readers for around €2.50 each.

I don't have experience designing PCBs but i would just start from the waveshare schematics and remove the components that I don't need.

I'd need around 100 units for my final product initially.

I have a Whirlpool dishwasher board 8267371 my dishwasher is giving me trouble so I found another board on eBay and purchased. In shipping one of the capacitors broke off, so I'll be replacing it. I also noticed browning on the board and asked about it here and it was recommended I replace all the caps in that general area along with the resistor and the diode. While comparing the board I bought on eBay to the board my dishwasher is currently using I noticed a couple differences. One being that a transistor is omitted at Q7 and it doesn't look like it broke off because on the under side the solder is smooth, as if it was made this way and this Transistor was omitted along the way in I guess maybe a redesign or board revision. I also noticed a plug looking thing added to the board at P12.

The other transistors in that row are marked with MAC97A8 320 I can't seem to find one of these. However I found a MAC97A8,412. Would this work?

Would it be worth adding the missing transistor or should I just leave it omitted?

First photo is the eBay board and second photo is the board the dishwasher currently uses.

So i have a nucleo-64 board and i want to make a carrier board and i want some pin header receptacles that support insertion from both sides.

I am searching in particular for the type that lets the pin rod pass through the connector and the PCB.

i think i saw them a long time ago and i have no idea how they are called , tho i am sort of sure it is SMT mounting

maybe i am remembering wrong and there is no such type but i would be surprised if there isnt.

Why do i need them like this? Well because i may need to stack some boards along common power and i2c busses and i though it would be nice to have this as a non solder solution.

THX in advance for your help.

ps can you also share some manufacturers and part numbers i order from mouser and lcsc most often but i can potentially also use other sites

Hello everyone, I have a Mechanical Keyboard and Mistakenly I have Ripped a diode in the PCB and after doing some research I found that using a BAT45A diode can fix My keyboard again.

I'm a BCA student and don't know much about electronics and stuff, I therefore request you guys to help me how can I fix My keyboard.

https://preview.redd.it/v5jripgkts9e1.jpg?width=4096&format=pjpg&auto=webp&s=df066bee37a4733967eb89a1d5463a284593752a

I have Marked the area where the diode is missing and let me tell you all the other diodes have "A3" mark on them, does this refers to model no or there is someting I need to be aware of.

Hi all,

I am looking for some intermediate-level audio projects I can do to get more into old-school audio protocols/techniques and learn more about analog circuitry (amps, filters, harmonics, etc) as pretty much all of my experience lies in the digital realm (Firmware/Hardware engineering for 2+ years). The purpose of this project would be to understand more fundamentals in audio specifically, so I can better understand things like RF and Power Electronics. I am happy to spend money on custom hardware but any open-sourced simulators and other tools to mess around with and understand would also be great.

Either some reading material or project ideas would help out a lot .. thank you!

There was a 2200uf 40v electrolytic capacitor here, I forgot to take a picture and instead took a mental note. That nite went through the shredder of my mind and now I’m stuck. There are no markings that I can see and I’m way too much a ‘noob’ to figure out the ground plane etc. Any help would be most appreciated Thanks in advance

I can’t find anything on the markings, I see that it’s a field-effect transistor, but I can’t understand what else can be replaced with a burnt one.

Hi, I want to model mosfets as a variable resistor in diagrams, so I can use them in series etc. But normal switching with load at drain doesnt work because the circuit has to be grounded.

I could place load at source and use an op amp voltage adder to drive the circuit but someone told me they are very power hungry at high frequencies. Mosfet drivers are really expensive nearly half the price of an mcu. That leaves me with the bootstrap circuit.

I tried looking at a video but couldn't understand what was going on. I don't wanna build something I don't understand. I need help to understand it

https://preview.redd.it/4nlhdpvcjs9e1.jpg?width=1269&format=pjpg&auto=webp&s=f2f52971e9e3b3ebbd4338feebde1d4927afe5b7

Here are my thoughts of recently:

When input is 0 npn resistance is 0 and mosfet gate is grounded so closed, capacitor charges When input is 1 npn resistance is infinite and mosfet gate can be opened.

If mosfet can be opened(which I can't calculate) then capacitor will discharge through two resistors to the gate

The problems:

Discharge voltage will be lowered because it passes through two resistors, so gate < source mosfet shouldn't open Guy said capacitors voltage would increase to 24 but how?

Thank you for your time.

I am very new to electronics and i am trying to build my own pcb in kicad. I am trying to recreate this circuit for a hydrophone project. So as the title said i have no clue what the yellow colored triangles are. I am also confused about the so called Supply pins on op-amp but that is a question related to the circuit itself so i wont bother you with asking it.

https://preview.redd.it/k0cmxzniis9e1.jpg?width=1024&format=pjpg&auto=webp&s=36a7c18e5a3d533f52da59b9530c0621536b1d14

Hello, I need help identifying this component as I'm not having any luck myself. It's in a crossover for a set of speakers from the early 70s. Any information would be awesome

I'm learning about summing amplifier. On textbook it says, the input voltages must not have opposite signs. Why is that? Instead, it explains when trying to subtract, this tandem configuration must be used:

https://preview.redd.it/7ywjxocvyr9e1.png?width=2361&format=png&auto=webp&s=0fd1d6cc5a2dcd172a55b05732072a6edaa7d7b4

where output of one inverted amplifier is connected as one of the input for the next summing amplifier. but i don't understand how this is different from just connecting negative voltage source straight in, since the output from first amp is negative anyway?

i can't find further explanation on my textbook nor internet, so any help would be appreciated.

Is this footprint/pads on the PCB for a SD card? Like a SD card holder/slot thingy to be soldered on?

The PCB is a GNSS chip breakout board, and the chip doesnt really support direct writes to SD cards as far as i know... So i was suprised.

TIA electron wizards.

Hi there,

First time ever posting on any sub. I set out to find what was this thing I pulled form a bin some years ago, but to no avail... Nothing alike on the inernet nor through good'ol Chat GPT...

As of my observations :

-Does not react to temperature (electrical properties/appearance).

-Does not react to magnetic fields (same as above).

-Has (or at least for a few moments) shown an internal resistance of about 50k Ohms.

I did not try to put any form of current through it, as I'd like to avoid damaging it... Or experiencing something more violent...
Does anyone has seen such a *thing* before ? What would it be ? What's the use for it ?

If you need any extra pictures, np...
Thanks for reading !

Total lenght is about the width of a credit card, the shiny bit running through looks to be a glass tube (<1 mm diameter) with an inside coating. Each graduation (right side of the white band) is 1mm.

They're from a glorious keyboard that suffered some water damage 2 LEDs are shorted and that plug for the switch is destroyed but I got it to work, but I still want to change it.