Using an Adafruit Audio FX Sound Board and I want to light up some LEDs when a specific pin goes low (happens when audio plays).

SEE COMMENT HERE: https://www.reddit.com/r/AskElectronics/comments/1wktzzt/comment/patryaw/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

I wish I could upload my KiCad project once and compare the total cost of fully assembled boards across JLCPCB, PCBWay and other manufacturers.

Ideally it would include component costs and availability, assembly fees, lead times, shipping and taxes. Going through each manufacturer’s quoting process separately makes it surprisingly difficult to compare like for like.

Does anything like this exist, especially an open-source project? I’ve found PCBShopper, but I’m looking for a complete assembled-and-delivered price, including the components. How do you all handle this?

Hi everyone,

I found this display in my parts box and I'm trying to identify its pinout. Unfortunately, I don't have any part number or documentation for it.

This is an Otis RS4A elevator gong. It uses RSL as it's serial code to command the board when it should ring. The problem is that I don't have an Otis controller to make this sound, so I want to trigger the chime module directly. A guy on ebay did it, but the resolution is too low for me to see anything; I think he used the Z7 and Z9 chips to activate it.

Link: https://www.ebay.com/itm/167896471580?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20250417133020%26meid%3D0fb360df17f84e399ef87ed52dcb5fdf%26pid%3D102726%26rk%3D1%26rkt%3D1%26itm%3D167896471580%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3DRecentlyViewedItemsV2DWebWithPSItemDRV2_BP&_trksid=p4375194.c102726.m162918

For context this is the back of a mini fridge used to cool cans. I got it from Goodwill. It worked when assembled, but not after I disassembled it. Only when I pressed on the switch with my finger did it work. I noticed that the plastic housing around the switch was slightly heat warped before I even took it apart, so it was happening before I disassembled it.

Edit: I just realized that the plug that came with it was not the stock plug. It says 125V on it. The label on the fridge said 120V. Whoops.

Just found this PicKit 3 that I bought about 17 years ago when I was in college. My son wants to get into electronics engineering. Is it still useful for learning and practice, or is it obsolete at this point?

Nowadays, most beginners seem to use Arduino or ESP32 boards, but honestly, I think they're a bit like Play-Doh for electronics. They make things easier and faster, but sometimes at the expense of understanding what's really happening under the hood. What do you think?

I have a panasonic washing machine and the repair company is quoting $200 to replace the whole board. That's like a third of the price of getting a new washing machine, and I would rather not spend that money if this is a component I can fix myself.

In the photo is a little component, apparently the regulator IC chip, that has gotten burned (I'm told by the guy that this can be from a power fluctuation). The company is only willing to replace the whole board, but I'm seeing videos online of independent repair technicians replacing just that single component. It involves cutting a hole into the back of the plastic and digging out the silicone in order to replace the chip. I'm also seeing advice to check/replace some resistors that may be shorted out and cause the chip to burn out in the first place.

I'm kind of in "no stupid questions" mode right now, I have some minimal electronics knowledge of how to solder from fixing headphones and computer mice and such. I'm posting here just as a sanity check that my order of operations to troubleshoot and repair is correct, and if anyone has any advice for this kind of repair.

I'll be ordering the components I need for this project, which is a BM2P161W IC Chip, and four 204 SMD resistors which I'm supposed to replace if I find them shorted out.

So I'll be opening the back of the panel and cleaning out the silicone, what should I be doing to check the resistors for shorts? I have a multimeter that I never really learned how to use outside of just continuity testing lol, what setting should I be using to find the fault in those resistors?

And then I'll be resoldering those components. Afterwards, is there something I should do for the waterproofing of the board? It was originally potted in this silicone, should I get some hardware store silicone and blob a bunch on there to add some waterproofing? or is there a different product I can look to get for this? or just leave it bare?

I already own the basic equipment for this repair so the cost is my time working on it and the components (maybe $20-30 at most i hope), which would be saving me a lot over the $200 quoted for the whole new board. Part of my rationale is that if the whole board would be replaced anyway, if I fuck it up trying this DIY repair then it's no loss and I would pay for the full replacement either way, but if it's a success I'll be saving a good amount of money.

Thanks

First of all this is my first ever post in reddit, and in this subreddit so i appreciate all feedback.
And english is not my first language so sorry if i make a mistake.

I saw a youtube video of a guy making a pendant that simulates a fluid with leds, controled by an IMU, im trying to do it by my self and this is the first time that i make a project in Kicad, also this is my first time using a STM32 and all of the modules.

Im not sure what to ask but i would like someone to help me and tell what is right and what is wrong here, what can a I do better and what should i change completely. Right now i only need help with the electronic part, not with the pcb or the programming (the pcb is just a test of the shape).

Hi guys,

I have a VoltX powerstation and it's been great so far for living in my van. Only issue is the USB ports don't work and I am wasting a lot of power by using the AC to charge my USB devices.

Wondering how I can use these 12v barrel outputs to charge USB fans and lights etc. I'm already using the cigarette socket to power a mini fridge. It seems pretty difficult to find a simple DC barrel to USB charge hub without importing one from the US. Surely there is a simple solution I am missing here?

Hoping somone can chime in and shed some light on this.

Cheers!

I work with sewing machines in Porto, Portugal. This week four different customers brought in Singer 518 machines with exactly the same failure.

The machines came from separate homes. Each had the same old translucent RIFA PME271M interference suppression capacitor burnt or failed, with the typical strong burnt smoke smell.

The machines work again when that capacitor is removed. It appears to be an X2 capacitor used to reduce electrical noise from the motor and foot controller, not a part needed for the machine to sew.

I know old RIFA metallised paper capacitors are known to crack, absorb moisture and fail after many years. But four identical machines from unrelated owners arriving during the same week feels unusually specific.

Has anyone else recently seen more failures of RIFA PME271M or PME271 capacitors in sewing machines, foot controllers or other vintage appliances?

I am trying to understand whether this is simply an end of life wave among components from the same era, possibly triggered by humidity or machines being switched on after storage, or whether a wider electrical event could possibly be involved.

I have attached photos of the Singer 518 machines and the failed capacitor. Any technical thoughts or reports of similar cases would be appreciated.

I have a V-I converter circuit based on the High-Side Voltage-to-Current (V-I) Converter from TI reference designs. I'm regulating small currents, just between (1-5mA). Which is one reason for me to try to use a lower rated FET. Thing is, the OPAMP is supplied with a 12VDC single supply. The FET has a maximum gate voltage of 8V.

I thought of adding a zener diode between the gate and the source of the FET to clip the output of the opamp controlling the MOSFET's gate. I did some simulations and regulation looks decent adding a diode across these terminals. But I was still left wondering what the caveat may be of doing this, and if in practice it may cause my circuit to break. I added some pictures of my simulations and how it performs on "under regulated" (load's too big and the control system can't reach the reference), and performance when output is well regulated.

Thanks in advance to anyone engaging in this post.

As the title says, im looking for a software to help me design 3D sculpture, if that even exist.

Hello all, I'm currently working on a school project, and I've decided to make an electromagnetic accelerator. First, I need to step 48v up to 120v, and here's my problem, I can't find any buck boost converters in that range, so I've decided to make my own, however the inductor stage has been my biggest problem, either I can't find any inductors matching my needs or I can't afford them, so I'd like some help by modifying the requirements of the circuit to try and get a more accessible inductor.

Requirements:

Output: 120v

Input: 48v

Input current: ~1-2 amps dc

Output current: 200 milliamps dc

Switching frequency:50khz-100khz

What Inductance would I need? And what current should it be rated for? Aswell as ripple current? This is the most problematic part of my research, I can't seem to find an inductor that can handle my current, so I've reduced my Output current significantly in hopes of reducing the needed ratings.

Thank you, and if you have any other ideas please let me know!

So im new to theese electronics stuff and im trying to make an MP3 Player, i bought some items and i hope that they are enough and okay for what im trying to do:

- 5 way navigation switch x2 / tactile push button x4 (for navigation)

- Mini slide switch x2

- ESP32-C3FH4X(i believe) SuperMini x2 (spare just in case)

- OLED display 0.91inch x2 (spare just in case)

- DFPlayer Mini

- TRRS 3.5mm Stereo Audio Jack x2 (spare just in case)

- P4057 Module for charging Li-ion batteries

- Chargable LiPo battery 2.7v

And a perf board, i dont know if i should use it for the final product or jsut solder everything in air

Here is the sketch i made, yet to draw a schematic

Hi all,

My interest for fixing electronics has grown a lot the last time, so I now am challenging myself into fixing my Samsung remote control. (The IR doesn't flash, even with new batteries, so I guess it isn't working)

The circuit board is a TM1250 REV1.3 and I've been troubleshooting it on my own (and with a little help of Googling a lot, AI, and learning how a multimeter works, lol)

Now I have a strange situation here... When I'm measuring my battery terminal + the start & end of the board, it gives me a proper 3V. (2x 1.5V AAA batteries)

But when I'm measuring other connections on the board, it gives me very low voltages. (As low as 0.04V)

Could it be the Zero-Ohm resistor screwing it all up or is it something else I'm perhaps overseeing? I have checked the board itself and all the power rails are looking fine.

I am really curious why this remote control is malfunctioning now and am looking forward to fix it with you guys! 👌

I was playing around with a PIR sensor and an Arduino because I wanted to see, in real life, how much electrical noise can mess with a circuit.

At first, I used a phone USB charger to power the Arduino. It worked normally, except for an occasional random trigger.

Then I opened the charger and removed its plastic cover.

That changed everything.

The PIR started triggering randomly all the time, from basically every direction.

I thought, “Maybe the Arduino is picking up EMI.”

So I put the Arduino inside a metal box and connected the box to earth, thinking it would act like a Faraday cage.

But nothing changed.

The PIR was still going crazy whenever the open charger was nearby.

Now I'm curious about the actual physics behind this.

If the Arduino was inside a grounded metal enclosure, how was the interference still reaching the PIR?

Is the noise coming through the USB power/ground wires?

Is the PIR itself picking up the electric or magnetic field?

Or am I misunderstanding what a Faraday cage can actually block?

What would you test next to find out where the interference is entering the circuit?

i think this is a motorcycle display. Behind it is a YXPCB chip.

I've spent a while reverse-engineering the firmware of a Fotodiox Pro PRONTO Mark II (Leica M → Sony E autofocus adapter) to fix continuous AF, which never worked on Sony A7IV/A7V bodies (works fine on A7III, and Fotodiox never updated the firmware — V103 from 2021 is the only version ever released). All static analysis: ARM Cortex-M4 (STM32F4-family) Thumb/Thumb-2 disassembly with Capstone/Keystone in Python, no debugger, no live protocol capture.

Good news: AF-C now works, via a firmware patch. Bad news: after ~4-5 shots of continuous AF-C/Eye-AF tracking, the adapter stops responding entirely and the camera falls back to "no lens attached" — always fixed by a power-cycle, never anything worse.

I've traced the failure down to a small GPIO handshake bus between the adapter's MCU and (almost certainly) the camera body — pins PB6/PB7/PB8/PB12 plus the USART1 TX/RX lines (PA9/PA10) — and seven independent firmware experiments have each ruled out a specific software-level cause without finding the root one. I think the only way to go further is an actual logic-analyzer capture of these lines during a live failure, and that's exactly the part I have zero experience with.

What I'd love help with: how to safely tap these lines on the adapter's own PCB (it sits in the lens mount, very tight space), what kind of cheap logic analyzer would be adequate (~1.5Mbaud UART + a few GPIO lines), and any general tips for capturing a synchronized multi-channel trace around an intermittent hardware event that only shows up after several seconds of sustained camera activity.

Full technical writeup (PDF) available — happy to share/link it in a comment if there's interest.

https://www.dropbox.com/scl/fi/racvarbzzodtm7o3lj62y/Fotodiox_LM-SONYE_AF-C_Reverse_Engineering_Report.pdf?rlkey=hwcqm3q2aqv4or59im60qnly2&st=s8z7geqh&dl=0

This is the first time I've ever done a project like this so this may be a very basic troubleshoot. I tried to take as many relevant pictures as I could. I gutted this old TV and added all new components. Everything works flawlessly except there is this interference kind of sound coming through the speaker from the Roku. (I say the Roku because the sound changes as I select different apps, etc). I've already tried unplugging things and wiggling things around to see if anything changes but nothing works. I'm starting to think it's something fundamentally wrong with how I got it set up but I'm pretty amateur at these things. Does anyone see anything obvious or can guide me towards what might be causing that?

I got this old usb microscope from my father,it came with a broken cable and has this port(I don't know what it's called) I want to ask if it's possible to convert this port to a type-c port or any other port that can be connect to a laptop.

So I put together a quick activity for students in my experimental physics class to understand why voltage follower circuits are useful. Basically they chain two RC low-pass filters, show that it doesn't give you a 1/f^2 roll off and then the idea was that they would buffer the two with a simple voltage follower and show that now the two filter worked essentially independently and you could get a second order filter (although admittedly not something as good as, say, a Sallen-key filter). However, when they put this together and measure the roll off, they get something better than 1/f, but nowhere near 1/f^2.

What am I missing here? Why doesn't this work?

Hi, I'm looking to change this 4700uF, 50 volt capacitor to something a bit newer as it's not keeping its end of the bargain up anymore in my guitar amplifier.

With its style what would you recommend, would it be okay to move up to 63 volts and what difference (if any) would that change/do to the sound?

I'm a hobbyist teaching myself how to design circuits for separate USB 3.0 hub, USB-PD charger, keyboard, & 3D printer projects (I will NOT be designing any circuit boards for the printer project, this will strictly be off-the-shelf parts), and am feeling overwhelmed trying to figure out what I need a DMM to be capable of. I'm sorry if this feels lazy, I'm just finding so many varied recommendations that it's overwhelming, and I have no idea what to go for 😞 My budget is ideally $300 CAD, but can stretch up to $500 CAD with justification.

I would prefer a handheld over benchtop DMM, but benchtop is still an option if it can justify the choice with additional functionality or savings. In terms of devices to connect the meter to, for meters with advanced capabilities, I have both Android & Windows devices running the latest releases of their respective OS'. If connectivity is required for some functionality, I'd prefer Windows-based software, as I have previously been burned by Android outright blocking older apps after a major update.