Reddit:Electronics

This is probably pretty common since there are 8 (EIGHT!!!) of these inside a cheap Samsung monitor, still, found it really impressive that this is (1) possible & (2) economically viable.

hi hi again :3

Can't believe it took so long to get them, but I had to fix a few things here and there. Then I made an order during Chinese holidays, and customs, as always, requested a description for my PCBs but didn’t contact me, so I had no idea I had to do anything until the store called me and told me I’d better call DHL right now (please add me to the whitelist <3)

Description of the setup. For frequency testing, I was using a signal generator and scope together. Scope input signal point is the electrode test point, and output is the Vout test point. This way, whatever happens with the signal between the signal generator and the electrode itself does not matter. For the heartbeat signals, I had both passive and active electrodes connected in pairs (positive and negative): Bias was on my left leg (just one, passive as before, you do not need any active electrodes there), the first contact point is around the collarbone, the second contact point under my heart on the last rib. Passive electrodes are connected using sticky gel pads, active electrodes only dry contact with and without conductive rubber (1 mm thick, bought it on Adafruit store, if I measure resistance from top to bottom it gives me around 300 Ohm). To connect electrodes, I’ve soldered wire for the ground and 5 V output of my Meower board (link is right at the end). I thought I would add noise to the power rail and it would be bad — no, it’s fine :3

So, electrodes do work:

• Frequency response almost perfectly matches calculations (you can see it on the schematic pic)
• It looks like we can go rail to rail; it cuts the signal at 0 and keeps it alive until you hit above 5 V.
• I haven’t seen any problems with noise or clicks or any other types of noise I could spot in the time domain
• Dry contact use case with just direct contact gives not amazing but really good results — rattle noise, movements, network noise (50/60 and 100/120 Hz noise) almost nonexistent. The difference is huge. I didn’t even get what was going on at the beginning, thought something was wrong
• Dry contact with conductive rubber in between gives almost the same results as just direct contact, but I feel like it picks up a bit more electrode movement itself. Maybe I had to use adhesive between metal and rubber itself, but if it sits on your skin and the rubber has good contact with you and the electrode - almost no difference.
• There is a pic with heartbeat seignals. Green line is active electrodes and orange is passive. you can see there not only 50 and 100 Hz network noise, but also spikes - i was tapping on all cable at ones and the only one which pick up rattling were passive electrodes. So, rattle goes away, network noise goes down by alot even without filtering - looks really good.

So - now I can say - if you found this post, electrodes are tested and they do work. Schematic is correct (unless proven otherwise, if so let me know please :3). Conductive rubber works just fine, and I feel like just for normal use for BCI it’s the best way, so there are no contacts with any metal and it’s a bit softer and more comfortable. Thank you so much to everyone who told me I’m stupid and found problems here and there. I can’t believe I made 10 mistakes in 10 components, but I did :3. Though I’ve learned a lot. Anyway, thanks again.

You can find active electrodes files here
https://github.com/nikki-uwu/Meower/tree/master/hardware

- This chip incorporated 2 chips in one package. The CPU die and the L2 cache die.

- The chip also had a superscalar design and a RISC-based processor.

- The gold finishes are for bond reliability and corrosion-resistance. Plus, they look cool

Hello r/electronics!

I've made a WLED compatible controller for a friend of mine, and I wanted to give something back to the awesome electronics community!

My controller supports:

• 4 high-current open-drain PWM outputs for analog 0-24V LED strips.
• 4 high-speed differential transmitters for driving 12V addressable LED strips using lengthy wires - the corresponding receivers (which can be soldered in-line with most LED strips) are also linked in the GitHub repo.
• 4x isolated optocoupler inputs (0-50V) for light switches, pushbuttons, and interfacing with other systems.
• An onboard USB programmer for easy programming.

If you want to make your own, all of the necessary files for production (gerbers, BOM, PnP files) are available in the repository, together with the schematics and a bit more information. Please do read the "Limitations" section before ordering your own copy; if you have any uncertainties, don't hesitate to reach out to me!

https://github.com/KuglicsL/LED_control

Hello everyone! Thank you for the incredible support on my first post. For my next project, I built a heart-shaped circuit with 15 LEDs on a zero PCB, designed to have a beautiful fading glow powered by a capacitor bank. I started by simulating everything in Tinkercad to get my component list, which proved to be a lifesaver. The build had its challenges, from getting the heart shape symmetrical to using mismatched capacitors to create the power bank. However, the biggest villain of this project was my 25W soldering iron—it just wasn't hot enough, making soldering a complete disaster. After a desperate Amazon order, a new 60W iron saved the day and made finishing the project a buttery-smooth experience! I'm incredibly proud of what I created. For a future version, I'm thinking of adding a USB-C port for power and finding a way to make the LED glow last much longer. Let me know what you think!

Hello, a little update from my recent post. I tweaked few things and organized a bit better. I also added the remote control. If you could please check and review the boards, it would help me a lot.

Thank you in advance

Project Description – 24V DC Motor Drive System with BLE Remote Control 1. Overview

The project consists of a complete 24 V DC motor control system that integrates:

• A main control board based on the ESP32-WROOM-32E microcontroller,
• A high-power Pololu G2 motor driver (21 A version),
• A BLE remote control module based on the Raytac MDBT42V (nRF52832),
• And CAN bus communication for external system integration.

The system allows:

• Local control via onboard buttons and sensors,
• Remote control via Bluetooth Low Energy (BLE),
• CAN communication for multi-device coordination in industrial or vehicular applications.

2. Main Control Board 2.1 Power Supply Chain

• Input voltage: +24 V DC from a battery or industrial supply.
• Protection elements:
  • 5KP30A TVS diode for surge suppression.
  • Fuses (1 A for logic circuit, 15 A for motor branch).
• Voltage conversion:
  • Buck converter (XL4015) steps down 24 V → 5 V.
  • LDO regulator (AMS1117-3.3) converts 5 V → 3.3 V for ESP32 and CAN transceiver.
• Filtering: Electrolytic and ceramic capacitors reduce noise and stabilize voltage.

2.2 Motor Control Section

• Motor driver: Pololu G2 High Power Motor Driver (21 A).
• Control signals from ESP32:
  • PWM (GPIO27): Controls motor speed.
  • DIR (GPIO23): Controls rotation direction.
  • SLP (GPIO21): Enables/disables the driver.
  • FLT (GPIO22): Fault feedback from driver.
• The motor driver is powered directly from the 24 V line, while the logic operates at 3.3 V.

2.3 Local User Interface

• Buttons (GPIO25, GPIO26):
  • Forward / Reverse control for manual operation.
• Sensors (GPIO34–GPIO39):
  • Four digital inputs for limit switches.
• Buzzer (GPIO16 + n-MOSFET driver):
  • Audible feedback for warnings, alerts, or connection status.

2.4 Communication and Expansion

• CAN bus transceiver: SN65HVD230.
  • Connected to ESP32’s internal TWAI controller (GPIO32 TX, GPIO33 RX).
  • Differential signals on CANH/CANL for robust industrial communication.
  • Optional 120 Ω termination resistor.
• External connectors:
  • 12-pin screw terminal for sensor and Pololu connections.
  • 4-pin power connector (24 V IN, buzzer, GND).

2.5 Programming and Debugging

• Programming header connected to TXD0/RXD0 (CP2102 bridge).
• EN and BOOT pins are pulled up with 10 kΩ resistors but no onboard buttons are mounted — programming is done externally.

3. BLE Remote Control Board 3.1 Overview

The remote control unit uses the Raytac MDBT42V (nRF52832) module to wirelessly transmit control commands (button presses) to the ESP32 receiver using Bluetooth Low Energy (BLE).

3.2 Hardware Design

• Power supply: 3 V coin-cell battery (CR2032 or similar).
• Optional LDO: only used if other peripherals require regulated voltage.
• Crystal: 32 MHz main crystal + 12–15 pF load capacitors, depending on PCB trace length.
• Buttons: Two input buttons connected to GPIO6 and GPIO8.
• Programming interface: SWD (SWDIO, SWCLK, GND, VCC).
• Grounding: Central ground pad under the module connected to main GND plane.

3.3 BLE Functionality

• Configured as a BLE Peripheral that advertises only to the ESP32 receiver (not visible to smartphones).
• Sends short control packets on button press events.
• Uses low-power advertising mode to preserve battery life.
• ESP32 acts as the BLE Central, scanning for and decoding packets from the remote.

3 inch to 8 inch. Fab has been around since the 60s. Currently the 8 inch is our production size but the 6 inch is still used in the company and they float around as engineering wafers.

My simple lab in my dungeon. Recently picked up the Kepco Programmable Power Supply and Agilent 54622D oscilloscope from work. We’re moving buildings and they’re tossing a lot of stuff. I’m running an Intel NUC with Win11, HP Slice with Fedora, RPi 4b (in the 3D printed green and black Fractal case) with RPi OS, and a Dogbone running Debian. It’s a very simple setup compared to a lot of yours but I love it. A nice place to escape.

Fantastic!!! STM32-based project with an LCD display and a PIR + temp module.
Simple, cheap, and surprisingly effective — perfect for those hot nights when you’re too lazy to turn the knob manually 😎

im k

I just parts-salvaged a Metz camera flash with a burnt-out charging transformer, and found this vintage beauty on the inside.

Tell me what you think!

This bloody LM2576-33 (new) gave out 10V instead of 3,3V. Killed two STM32 before I figured out WTH was going on.

I am, of course, going to widlarize it, as it it written in the ancient scrolls.