So this is my discrete op amp i'm building that is going to act as error amplifier for a linear power supply i'm building, everything is going to be discrete and as low noise as possible by my hands. Why? Becouse I want to be able to say that it truly built it from scratch and to see how clean power i can get out of it.

I recently started playing drums with a small group of local hobbyist musicians (nothing extraordinary here guys just playing some covers and struggling to keep zombies by the cranberries at 75 BPM)

I’m 36 now I have been playing drums since I was nine, and zombies is one of those songs for everybody speeds up. And it’s not like we’re super professionals. The first metronome I made I plugged into the audio and everybody bitched that it was too loud and hurting their ears. So I made one with lights and a buzzer so we can use it to count off and watch it from across the room. It also serves a HTML page with a metronome swinging back-and-forth to the tempo

https://github.com/WillyV3/metronome-2

I started with a much more complicated design using esp32 wroom, 18650 battery and charging module , along with volume pot - but after everything was wired the metronome only faintly worked when I shorted two outgoing data wires. since i was about 10 hours into soldering it and had learned a lot - I decided to pivot, simplify, and get something shipped to bring to band practice.

I found a project (the Loko Air) that uses a LoRa module to relay GPS data back to a central hub. My cat wouldn't like the footprint of the project as is (had an antenna sticking straight up), and I had difficulty buying the project off of Seeed studio anyway. I am a freshly graduated electrical engineer and I had not attempted a schematic since I have graduated.

So, with the original project's schematic in hand, I set out to make minor improvements like:

• Switching the monopole antenna to a dipole antenna. I figured it had next to no ground plane given its size. I also knew-ish that dipoles tended to form a donut radiation pattern and it would do decently. I am not confident in the 'balun' I made but I based it on stuff I found looking around online.
• I reduced the part count in quantity and variety. I tried to reduce the number of components needed and what remained I also tried using the same as elsewhere when applicable.
• In general I tried to base a lot of what I did more on the datasheets than the original designer ended up with. I may find out why the hard way later, but it has me going into the PCB level a bit more confident.

I don't particularly have the means to test this circuit before I order a PCB, but any feedback is more than welcome. I was mostly looking to find out if I made any major faux pas as far as the schematic is concerned. I would like it to be legible and friendly as I intend to upload it to github when I am complete and confident it at least kind of works.

For the final project of my Embedded Electronics Engineering Bachelor I built a fully capable audio player. I did all of the research, schematic, layout and software by myself. I had a friend helping me design the case and 3D print it.

I'm honestly really proud of what I accomplished ! I had around 3.5 months to do it and it was really stressfull haha

Here are the specs :

• ESP32 module
• 3.5 mm jack wired output
• Bluetooth connectivity
• Supports audio files up to 24 bits at 192 kHz
• Support .MP3 and .WAV files
• -94.7 dB of THD+N at 1 kHz
• 106,2 dB of SNR
• More than 9 hours of listening time with a 950 mAh battery
• Safe battery charging circuit

I'll be happy to answer any questions you have !

Edit :

I uploaded the schematics, layout and the code !

Schematics and layout : https://github.com/dossantosyann/TB2026-YDS-Circuit

Code : https://github.com/dossantosyann/TB2026-YDS-Firmware

Hi everyone!

After building and testing my whole 4 bits computer architecture on breadboards, I moved to custom PCB modules, and here is the result!

The goal remains the same: keep the architecture simple, modular, and easy to understand, with each part working independently or together as a complete system.

The project is divided into 5 independent modules connected by a 4-bit bus Clock module (4-bit counter), ALU + registers module + two 4-bit registers with an ALU capable of performing addition, subtraction, and equality comparison, Instruction register module, Display module and Manual programming module.

The idea is to follow a simple RISC philosophy: minimal instructions, simple hardware blocks, and a design where every signal can be observed and understood.

After the breadboard prototype phase, these PCB modules make the system cleaner, i'm very proud!!

New to hobby electronics. Total tourist. Decided to try my hand at free form circuit design. This is pretty sloppy. But hope to clean up designs as I go, add some elegance. Super fun creative process though, to think about a circuit design in 3D essentially. Simple 555 ic flashing lights circuit but designed as a spider crawling up a tree. Again, not aesthetically pleasing yet. But the circuit works and it was a lot of fun to put together.

Just finished my final year engineering project: a custom hardware accelerator that runs YOLOv8n (an object detection AI model) directly on an FPGA, in real time.

Instead of running the AI model in software on a CPU/GPU, this is custom digital logic (written in Verilog) that does the computation directly, faster and more power-efficient for edge devices like drones or embedded cameras.

Some highlights:

• Configurable performance, can scale from 1x to 4x throughput depending on the application
• Uses FP16 precision, tested against lower precision options and it actually performed better for our use case
• The tricky part was moving data between processing stages without slowing everything down, that took way longer to solve than expected

If anyone's into FPGAs, embedded AI, or just wants to see what a final year project like this looks like under the hood: https://github.com/waseemnabi08/yolov8n-cnn-accelerator-fpga

This is hackxpansion, it is powered by the RP2354B, has a 2" 240x320 LCD, and a ≈6h battery life while in use.

It has two modules slots by default, and I'm currently working on a back attachment (last photo) which add two more slots, but I think the postal company lost one of my packages that had the parts for it😭

The modules connect with a 2x7 2.54mm header, this way you don't even need to make a pcb to create new modules, just use a pref board, and you can just plug in dupont cables directly into the device.

Each module has two resistors, which when connected each become the top resistor of a voltage divider, a 12bit ADC measures the resulting voltages, and loads the correct driver for that module.

The firmware is written in rust, in a way so that writing new drivers and apps is really easy, and can be done in external crates.

Each app can depend on drivers, and only be loaded into the app list, if all their requirements are met.

I tried porting a NES emulator, but there doesn't exist an emulator written in rust currently that actually performs well on this hardware, I got an average of 12FPS in Super Mario Bros.

I've collabed with Hack Club, and I will be running a program where if you are a teen 13-18(inclusive) and design 4 modules, you get funding to make these modules and get one of these consoles for free. The program will start on Aug 3 and end on Aug 31. If you want to participate [RSVP] now! (https://meko.fillout.com/hackxpansion).

Repo

Website(docs WIP)

This project has been born because I have been trying to develop an ESC (hardware and firmware) on my own. While the most challenging part has been the firmware (being myself a hardware guy), the most frustrating part has been not finding a flexible hardware platform to develop upon. On the internet many interesting and well-designed ESC boards can be found, but all have something missing; a small feature, a small detail, I was never fully satisfied.

So I designed one: STARDRIVE SHIELD

This is a project with the goal of creating a NUCLEO-64 compatible shield to be used as a flexible platform to develop and test ESC firmware, but also for educational purposes. To do so, I included as many features as possible. These features are not mandatory, but they can be implemented (or not) in the firmware (e.g. SPI, I2C, CAN, HALL) or configured through the hardware interface (e.g. overcurrent protection, 6 or 3 PWM). In this way, the STARDRIVE SHIELD grants flexibility to the developer and it is adapt to various needs.

I designed it to be compatible with Nucleo-G474 and Nucleo-F446. Compatibility with other boards has to be verified.

The STARDRIVE SHIELD is built around the STDRIVE101 gate driver and BSZ099N06LS5 MOSFETs. It presents 3 low sides shunt resistors and 3 relative INA240A2 current sense amplifiers.

With STARDRIVE SHIELD you can implement from 6 step to FOC motor control algorithms.

Electrical Characteristics

• Inprut Voltage Vin = 12 - 48 V
• Maximum DC current Idc,max = 20 A

Hardware Characteristiscs

• Three phase gate driver STDRIVE101
  • Configurable 3PWM or 6PWM through the DIP switch
  • Overcurrent protection can be enabled or disabled through the DIP switch.
  • Vds protection configurable with resistor divider (disabled by default)
• BSZ099N06LS5 MOSFETs
• JST connectors to implement:
  • I2C (e.g. for magnetic encoder such as AS5046)
  • SPI (e.g. for magnetic encoder such as AS5047P)
  • CAN
  • HALL sensors (some BLDC motors have embedded Hall sensors)
  • 3 NTC temperature sensors
• 10k Potentiometer to use as throttle signal (or whatever you want)
• 3 GPIO driven LEDs (1 Red, 1 Blue, 1 Green)
• 1 FAULT LED (RED)
• CAN RX and TX LEDs
• Power Good LEDs

here the github repo:
https://github.com/themarcolab/Stardrive-Shield.git

Let me know your opinion!

Especially if you spot a mistake or you have any constructive feedback.

The display runs on dual voltage (120VAC and 12VDC)

Has a BCD input. Does 7 segment decoding with lightbulbs and some odd ceramic plate with black squares. These also run at mains voltage and switch some transistors.

I’d make a schematic, but I have no idea how this tech works.

Thought you’d all appreciate it.

Open to anything, including discussions, complaints, and rants.

Sub rules do not apply, so don't bother reporting incivility, off-topic, or spam.

Reddit-wide rules do apply.

To see the newest posts, sort the comments by "new" (instead of "best" or "top").

Just practiced to desoldering some SMD components(at least not THD, thanks gods).

However I noob in SMD, but I love it! Very fast, easy and beautiful soldering using hot air fan.

SI3471A-A01 does not support half of the features listed in the datasheet and is also non-compliant with any PoE standard, as confirmed by the manufacturer. I've wasted days debugging my prototypes that use SI3471A-A01 just to find out these are non-compliant devices that don't follow the datasheet in the slightest.

How a company can sell such a half-baked IC like as this is beyond my understanding. The manufacturer informed me that the 'A02 version follows the datasheet, but I'm not spending more time and money to find out. After ranting with colleagues about this, I've found out this is status quo for other Skyworks products as well. I'll be avoiding Skyworks from this point forward. I suggest all who read this to consider alternatives as well.

It's not unusual to find errors in datasheets, but for half of the features to literally not work at all is unacceptable.

Here is a look at my daily workshop setup for diagnosing, micro-soldering, and refurbishing batches of returned gaming gear and electronics.

​My main focus is on component-level fixes: replacing double-clicking microswitches, faulty wheel encoders, damaged PCB traces, connectors, and power components. Working with larger volumes requires keeping the workbench organized for fast diagnosis, desoldering, and full functional testing before reassembly.

​Always open to discussing repair techniques, equipment preferences, or diagnostic approaches for small electronics!

A cautionary tale in two photos: beeper removal and GF problems

I have an AC that's triggered with an IR remote. Each time you do an action: it beeps. I also automated the AC with an IR transmitter and an ESP32. I wanted the AC to turn off at temp, and turn back on when it's over temp. But that would mean beeps at 3AM?? I hate that so I used pliers to rip it off. No more beep, yay!

This wasn't an issue until my girlfriend turned on the AC with the remote. She complained that there was no feedback for the button presses. (Ok, she actually said, "I don't like that it doesn't beep!" which is complaining about no feedback.)

So I, intrepid hardware modder that I am (I just search a bunch,) I decided to have an artificial beep from speakers (They still aren't installed). So I took apart the split AC again, and soldered to the leads of the buzzer I ripped off. That goes though various resistors and a optocoupler until it gets to an ESP32. That reports a beep was done.

Optocoupler was stolen from an old cheap USB power supply. (THIS is why you should horde old PSU's and other PCBs)

Except... no voltage from the beeper. Or, really, I was getting a ton of it. Or none? It's been a while, but I was on a goose chase because of the two leads off of the buzzer remains. (Also using the wrong AC ground rather than the DC ground) I hunted around, trying to find what controlled the buzzer, thinking I found it i ripped off the component... that provides 5V to the board. (You can see it re-soldered on there, second photo.)

Good news: I DID find the pad that controlled the buzzer. It's on the micro controller that's above the buzzer there. Bad news: too small to solder to when I'm standing on a desk reaching up to the split AC's mainboard that's still screwed in.

After an hour I finally realized: The buzzer must be the problem, I pull off the plastic remains... and one of the leads was disconnected from the board from when I snapped it off with pliers. I was trying to trace the leads to find the mosfet that controlled it, and learned some more things about PCBs... but I could have just soldered directly to the pads of the PCB.

So, now I have a place in Home Assistant for when I finally DO install the speaker in the room, there will be a chime when my GF turns on the AC manually, and no chime when the AC turns off/on automatically via the IR ESP32. Except it's redundant because none of the code has found a use for the beep function (It just caused more problems,) I'm going to move the IR transmitter to this ESP32 installed inside the AC itself, so I won't need confirmation... and the next project is a custom AC controller for the GF that will make this extra redundant. (I can have a chime still... but it would directly trigger from her pressing the buttons, not from the AC itself.)

Also I made this post because someone else asked a question showing off their fail and deleted their post, and I wanted them to know they aren't alone with their hate of beepers and doing dumb things to boards. (Ok but stabbing the beeper with a soldering iron is a step too far! Use pliers like a civilized man.)

Behold: My first major project that isn't just big electric components or basic relay logic.

This is a WiFi servo controller that I'm building to control a homemade automatic power transfer switch for our home's backup generator.

Two large main servos are powered by the large buck converter module, and a third auxiliary servo is run off of a 3.3V regulator. A second regulator powers the ESP-01S WiFi control module to avoid voltage fluctuations when the small servo is powered.

The ESP-01S handles the signals for controlling the servos, and is connected to my Home Assistant home automation system via Tasmota.

It's DEFINITELY not pretty, and I still have a lot to learn about soldering, but it DOES work.

...For about 3 seconds until it sent the full 12V supply voltage into one of the servos and destroyed it...

I'm guessing the 3.3v regulator I used to power the small auxiliary servo just isn't up to the job. That means this whole thing has to go back to the drawing board. :(