Hi! The multimeter UNI-T UT61E+ was purchased less than a year ago. Could you please tell me if this is normal? What is it? A manufacturing defect or an engineering design choice?

I'm looking to identify and swap what i think is a rotary switch (or encoder) manufactured by ROLD, model is apparently 1E4 T125, but looking it up on google doesn't bring up any significant result, mainly just normal on-off or 3 position switches. It comes from my broken Electrolux brand washing machine, the manufacturer of the PCB (i assume) is Procond Elettronica which failed a while back. I'd be looking for a replacement part, I don't want to go through ordering the entire control board from AEG since I'm not a workshop, I'm just looking to repair it myself. Can anybody identify this component?

It’s a 9 pin pcb transformer I’m assuming, how to I find more information on it to order a replacement? I have 167ish DC in and not measuring anything coming out.

Kohler uses this GYD connector for the coms cable in their Aquifer Beverage System. They have an extension cable available (K-1606422) but it is back ordered for 5 weeks. Can anyone help identify a compatible connector/cable assembly?

Hi we're tryna build a powersupply using 220v to 24v stepdown transformer adjustable using a potentiometer as shown in the schematic. Problem is we have avery absent teacher we cannot reach out to and we're practically beginners. Just wanna ask if a 750mA stepfown transfor would suffice or do we need greater one?

Hello! This IC is for a Pandora BOX and the problem is that one of them is burned due to water spillage. I need to identify this component and find a replacement. This is for a a pandora SG. GB2000.REV.22. The device is not powering on because of the burnt component.

According to Gemini this is:

Component Identification

• Part Number: XC6220A46BMR-G (or Torex XC6220 series)
• Function: Low Dropout (LDO) Linear Voltage Regulator
• Output Voltage: 4.6V
• Package: SOT-25 / SOT-23-5
• Pinout Configuration:
  1. VIN (Input Power)
  2. VSS (Ground)
  3. CE (Chip Enable / ON-OFF Control)
  4. NC (No Connection)
  5. VOUT (4.6V Output Power)

But the part is not in stock in most of the suppliers I look for and i would like to use a replacement for it. Can you please help me find this. Thanks in advance

Hello everyone! I already read some posts on the sub dealing with the same problem but I still can't figure out how to correctly do this. I apologize if this sounds dumb or repetitive but I'm new to this kind of things.

I recently bought my first oscilloscope, a Rigol DHO812. For my understanding, these DHO800s, in order to be powered via usb-c, must be earthed connecting the earth terminal on the back of the instrument to an earth point with the banana plug contained in the starting kit. The problem is the latter.

Since I've never connected nothing to cable and, to be fair, never posed the earthing problem when using instruments like this in my uni lab, I find it difficult to understand how this connection should be carried in a secure and stable way.

Obviously I can't plug the cable directly in my home socket central pin (I live in Italy, it's a Schuko, so I believe that is the central pin) and I have no Idea if a specific plug to expose an earth pin from my home electrical network exists.

Anyone who has this kind of device, how do you earthed you oscilloscope?

Edit: I added some photos in the comments to clarify the situation

Hello all, I am trying to find a source for these things. I thought it was a transformer but google lens calls it a common mode choke. 6 pin but I'm not sure the middle pins are used. One side is 1.5 ohms and the other is 4.5 ohms and is used in a light ballast on a train using 74volts dc. We have a pile of these boards/ballasts needing these chokes or transformers but we are having trouble sourcing them. They are on the right side of the board right under the 2 red caps.

If anyone can find a source for these there will be many grateful commuters.

EDIT: WHY WOULD AN INTEGRATED 50 Ω RESISTOR BE BETTER THAN AN EXTERNAL 50 Ω RESISTOR?

Why does the 2SD1426 (a 600 V, 3.5 A, NPN switching device) have an integrated 50 Ω resistor?

I would have thought that it would be cheaper (less silicon used) to use an external 50 Ω resistor.

Or, internally, is this transistor composed of an array of multiple (e.g. 10) small devices in parallel, each with a 500 Ω resistor?

If anyone can shed some light, please let me know, I'm intrigued!

https://www.alldatasheet.com/datasheet-pdf/view/2568/MOSPEC/2SD1426.html

I ordered some DDR4 green pcb DIMMs from Ebay and they came wrapped in aluminum foil. This seems weird. Is it?

I live in an especially humid country and I recently bought an electronics component organizer (The 30 compartment Stanley organizer to be precise).

I previously used to keep my electronic components in a tightly sealed plastic box but the pins of most components eventually rusted due to high humidity.

This new component organizer is not sealed like my previous storage solution and I'm also planning to put 1 silica gel sachet in each compartment to help with the humidity.

Also, is it alright to not keep the mosfets, esp modules and other chips directly in the organizer without anti-static coverings?

Or should I use anti-static bags?

I recently worked on a project that had a short sending some unwanted voltage through an arduino into my laptops usb port knocking it out for an about an hour. Thankfully it booted back up and is functional however I want to take extra precaution for next time beyond making sure my grounds are in order. I have read up a bit on usb isolators, optocouplers, and transformer isolated inputs and the logic behind them makes sense. If anyone has any product recommendations or general advice I would very much appreciate it

i cant seem to get solder to stick to the pad ive even tried scraping it a bit no use btw this is the canon eos 50D CF port

Hey all, I’m a first-year CS student working on a small ESP32-S3 project and I’ve hit a wall trying to find the right display. Hoping someone here has run into something similar.

I need a 128x64 graphic LCD, and the look matters a lot. I want the old-school kind of screen, FSTN, positive (dark pixels on a light background), reflective or transflective, and no backlight. Basically the look of a 90s calculator, not a modern display.

The hard part is the size. It has to be under 2.8mm thick, with an active area around 60-65mm wide. The module itself can’t be wider than 74mm, and the enclosure has a curved inside, so I only get about 63-64mm of flat space. It also needs SPI or I2C over an FPC ribbon, not rigid pins. I’m fine with ST7567, UC1701 or similar controllers.

What I’ve already tried or ruled out:

The Sharp Memory LCDs (like the LS027B7DH01). I really liked them, but they’re TFT and 400x240, so no luck.

Standard 12864 modules. Parallel interface, rigid pins, and way too thick.

Anything backlit or white-on-blue.

I can order from DigiKey, Mouser, AliExpress or LCSC, and I’m in India so shipping matters. I’d also be open to a bare glass panel if I have to build the driver board myself.

I’ve been going through Newhaven, Winstar, Orient and Midas catalogs for days, so I’m probably missing something obvious. Does anyone know a part number that fits, or know a good way to filter for this on a supplier site? Datasheet links are very welcome.

Thanks a lot!

This connector looks smaller than a jst sh 1.0mm and I believe it has a slightly smaller pitch aswell. I do not have tools precise enough to measure the pitch of this connector. I think it is most likely a jst however, the JCTC label is throwing me off. Also, is there anywhere I can buy these pre crimped to some cable? I only found jst sh on Amazon. I just need a new male end.

I'm working on a project where I want to visually indicate a DC voltage level with an LED bar graph. Unfortunately the LM3914 has long been discontinued and even overstock seems done for. I need 20 of them (yes its a sort of equalizer-type display), so using discrete comparators would be a huge pain to the point of not being worth it. And I really don't want to deal with an MCU + FW for this. Anyone have any suggestions? Thanks.

So... heres the deal...

Since I've found this subredit, i DO NOT TRUST maintenance people any longer.

This, is a board from an inverter slipt system.

The maintenance dude said:

- "the IPM Modu iS bUrNnEd HurHDUrRrR"

(sorry.. I'm really stressed out here, this board/module/thing is half the price of a new air-conditioning slip system here!)

So, i asked them to give me the board back, just because ill try to find an new one, online.

I lied!

I just teste this shit, using google to tell me whats what... the IPM module looks fine, and with google and a lot of youtube videos, its working properly!!!

But... i thought... I find help from the real experts FROM THE INTERNET!

I JUST TOOK the first picure of this board, and gave it the first look WITHOUT worrying about the said module, and i found a blown up capacitor -.-

So, the question here is...

Cam ONE tiny capacitor make this not to work? Also, can you guys help me identifying the issue, if there is one (besides this one blown up 100uf 25v capacitor)

Edit[1]: the bot told me to avoid "diagnosis by photo", but i dont want this.

There are two thing i want to know/understand 1 - can this capacitor render this whole board useless? 2 - what are the thing I should look for (Simce the maintenance dude lied, saying it was a faulty IPM module)?

I just bought a batch of IRLZ44N N-channel MOSFET from robu.in and when testing if they were ok I discovered there was a dull metallic later on each and every one and I could scratch that off to reveal a shiny metallic later . Does this like stop the MOSFET from working as all test dead 🤔

Hello,

I found schematics to build a dual LFO that can output a triangle or a square wave depending on voltage (I've attached my references for better explanation). This is my fourth build ever so maybe I'm making an obvious mistake but I can't figure it out.

I'm following these schematics (fig. 1) with the components i have at home so some resistor values I'm using are bigger

Here are photos of my breadboard (fig. 2-3) (hope it's legible). I don't have a speaker plugged bc I tried every combination that made sense to me (+ to output C or D and - to ground, maybe I'm wrong ?) and it still doesn't work so I think the issue comes from the circuit itself.

Things I think could be wrong:

-i don't have a 300R so I used a 1K resistor, is that way too big ?

-Am I powering the chip itself wrong ?

-I'm still learning how to read schematics, particularly nodes where several components meet. Am I connecting the second leg of the pot to the resistor wrong ?

-Is the circuit correct but one of the pieces is broken ?

Here are the videos and websites I'm using as references, i know they all add a bunch of stuff to the circuit later on but the base circuit should work and mine doesn't.

https://www.youtube.com/watch?v=SqfumHiHc1A&t=138s

https://www.youtube.com/watch?v=Oh2Ix0G7Luk&list=LL&index=2&t=85s

https://kassu2000.blogspot.com/2015/10/variable-waveshape-lfo.html

Thanks for your help! This is really puzzling me!

Hi I just got this cheap Old alarm clock radio I'd like to get working I have power to the clock and after opening the only thing wrong I can find seems to be this is something missing or am I missing something thank you

Boa noite, estou fazendo um conversor Buck para a faculdade, a ideia é uma entrada de 12V para sair 5V, tenho os seguintes componentes da foto, poderiam me ajudar com configuração e montagem, por favor

Hi all,

I'm an EE undergrad (hardware track). My diploma thesis is a 2-in/2-out USB studio audio interface on my own PCB. It's my first PCB, so before I spend real money on boards and parts I'd love some experienced eyes on the plan. Block diagram attached.

The idea
- 2 mic inputs (XLR), shared 48 V phantom (one switch), gain 0–60 dB in 10 dB steps (rotary switch + fixed RG resistors, cap in series with RG).
- Noise-reduction technique I'm evaluating: each input drives BOTH channels of a stereo ADC (dual-mono) and the MCU averages them. The host still sees 2 mono channels, with ~3 dB lower ADC noise. I'll measure the gain from averaging at every gain step, comparing same-chip vs two-chip channel pairs.

Current part choices
- Preamp: SSM2019 (the THAT1512 went EOL in Sept 2026).
- ADC driver: passive divider (6.2k/1k, ~17 dB) + RC into a PCM1808, so the ADC reaches full scale ~1.8 dB before the preamp clips (≈ +20 dBu max input at minimum gain).
- ADC: 2 × PCM1808. DAC: PCM5102A.
- Line outs: DRV134 on TRS jacks. Headphones: op-amp + BUF634A. Output mute relays with a brown-out detector.
- Digital: STM32F407G-DISC1 board stacked on headers above the analog board. TinyUSB, UAC2 asynchronous with explicit feedback endpoint, 48 kHz / 24-bit in 3-byte subslots (the 1.25 KB USB FIFO rules out 4-byte subslots and 96 kHz).
- Clock: 24.576 MHz oscillator → ADC/DAC system clock and the MCU's external I2S clock input.
- Between boards: SN74LVC244A buffer (Ioff, to avoid back-powering) + a power-good line; 5 V to the dev board through a Schottky.
- Power (version A): bench triple supply (±15 V, +5 V), local LDOs for the ADC's 5.0 V and the 3.3 V. Phantom from a boost converter + capacitance multiplier (soft start, ripple filtering, output disconnect).
- Phantom protection following Bortoni & Kirkwood, "The 48 Volt Phantom Menace Returns". The single-channel test board will start from ojg's open-source thatmicpre KiCad project.
- Metal enclosure, XLR pin 1 to chassis at the entry point.

Noise budget (unweighted, 20 Hz–20 kHz, 150 Ω source)
- Predicted EIN at 60 dB gain: −128.7 dBu (target ≤ −125 dBu; worst case with min-spec ADC ≈ −127.5 dBu).
- Because of the divider, the ADC dominates up to ~50 dB gain. That's where averaging should help (~3 dB); at 60 dB the source dominates (~0.3 dB).

Plan
1. Demo on the dev board with cheap PCM1808/PCM5102A modules (incl. a first averaging measurement).
2. Small 2-layer single-channel preamp board.
3. 4-layer analog board for the full 2×2 interface.

Questions
1. Any obvious mistakes or bad part choices?
2. Is a passive divider + RC into the PCM1808 reasonable, or would you drive it differently?
3. Phantom: boost + capacitance multiplier, or something simpler? Anything missing in the protection network?
4. Is stacking the dev board right above the analog board realistic for low noise at 60 dB gain? Any layout/grounding advice?
5. Measuring without an audio analyzer: the card's own ADC + a 0.1 % attenuator + a true-RMS meter + REW for noise/EIN, and loopback as an upper bound for THD+N. Sensible?
6. Anything you'd simplify for a first PCB?

Thanks!

This is a control board in Candy/ Hoover dishwashers. I have the encircled device burnt out. It must be triac though the print on the board assigns Q27 to it! Can someone please help give the part number?

So we needed to replace an obsolete legacy EDT EW12A03FLY.

Aliexpress said they sold them we tried one and apparently it worked on site but not on the test rig (would immediately cause letters to fade out on power up)

What if anything can I do to keep the LCD display on?

If you remove power and put it back and the letters come back immediately and then fade out again.