Reddit:Electronics

i think it is so funny how digikey packages their stuff. i ordered a pnp npn transistor pair and one came in the standard antistatic pin cushion the other came in a make shift package id describe as a chunk of plastic cut with four very intentionally placed rubber stoppers. they are trolls and my favorite company

I built a scientific calculator from scratch: custom PCB, custom FPGA firmware, and a CPU I designed myself in Verilog.

The physical build: a custom main board and keypad PCBs designed in EasyEDA and manufactured by JLCPCB, an Altera Cyclone II FPGA as the brain, an LCD display, battery with charging circuit, and two ROM-flashing connectors on the sides to update the firmware.

Under the hood it runs a nibble-oriented CPU I designed specifically for BCD arithmetic: the way decimal calculators should work internally. I then wrote ~4K of machine code implementing the full set of scientific functions: trig, logarithms, complex numbers, statistics, all verified to 14 significant digits against a dedicated test suite.

The full stack:

• Custom CPU in Verilog: Harvard architecture, 12-bit ISA, 8 registers, hardware fault detection
• Hand-written microcode assembler in Python
• Verilator + Qt simulation framework for development and debugging
• Custom PCB (EasyEDA / JLCPCB), battery, charging circuit, 3D printed case

The finished device is sitting on my desk.

Live WebAssembly demo (runs the actual Verilog + microcode in your browser): https://baltazarstudios.com/files/calculator-d/Calculator.html

Write-up: https://baltazarstudios.com

Source: https://github.com/gdevic/FPGA-Calculator

Hackaday: https://hackaday.com/2026/05/13/build-the-cpu-then-build-the-calculator/

Happy to answer questions about the PCB design, the FPGA setup, or anything else.

Una vez que lo pegues, ya tienes todo listo. ¡Dale al botón de Post (Publicar) y habrás terminado el proceso! 🚀⚡

Food Ninja turned reflow oven! My first board in 15 years went great other than my bad designs! Attempt at building a 6 channel sonar, dint go so great..... worked in air but not in water.

For years, devices like the RbPi have been described as “credit-card sized”.

And of course the message is rather the footprint, but at some point I became obsessed with taking that idea one step further:

What would it take to build something that is literally sized like a credit card?

I've got a slight feeling that you really don't seem to like questions here, but I hope this rhetorical one is okay :P

That question slowly escalated into months of experiments to find solutions for things where default methods won't work. I can't use large, rigid components, connectors, and find a way to make my own custom flexPCB.

And after months of tinkering, I made the first prototype. Fragile, but it works within the goal of not exceeding 1 millimeter. Somehow, news pages have picked this up and described it as "revolutionary" which is a bit far fetched, but I feel flattered 🤭

To be fair, 'computer' might be a little overstatement, but it's technically perfectly within the definition of one. If you should have suitable words for it that sounds cool, feel free to suggest ^^

The prototype includes:

• ESP32-C3FH4 w/ WiFi & BLE
• NFC read/write
• 1.54" 200*200 E-Paper display
• ultra-thin LiPo battery including charging circuit and power path management
• accelerometer

Finding small/thin enough components wasn't really the main challenge, mechanical stability was. Solder and general material fatigue, pressure distribution (particularly focused pressure) and other strain related issues were the real problem.

This doesn't even include battery protection and some other things to solve.

At this scale, the project turned into a weird mix of electrical, mechanical and chemical engineering.

A few things that became clear over time:

• preventing strain is much easier than surviving strain
• tiny real-world tolerances start dominating the entire design near the physical limit
• many “thin enough” components stop being thin enough once assembly is considered
• FPC connectors are basically obsolete, forcing me to get creative and solder each single wire for each 0.5mm pitch pad one by one.

The prototype is fully self-powered and running from its internal battery.

I documented a large part of the engineering process, including the process of etching my own flexPCB, on my GitHub repo.

And yes, it's not like this thickness is a necessity, going just 0.5mm thicker would probably have saved me months of engineering. This entire project was probably motivated way too much by the 'disbelief' factor 😄

I am curious on your thoughts on this! :)

Finally got a working prototype for my cars instrument panel project. Just running a test script for now to make sure everything works at the same time.

We've got the gauges, warning lights, and LCDs to display the milage.

More updates will come as hardware is added and the actual code is written. GitHub link for anyone interested

Started designing a few joystick cap styles for KY-023/Arduino joystick modules and thought they turned out pretty nice.
Made a classic version, textured grip version, tall, wide, and short variants.

if you wan the model:
https://makerworld.com/en/models/2792322-arduino-joystick-cap-pack-5-variants#profileId-3105095

This is a HUD75 LED panel that is being driven by an ESP32-S3! I am using this library as a driver and this library for the animation.

I have a custom animation that I loaded up and I plan to make more animations from here and turn it into a pet game!

I'm looking for cute names though!

After some hardware fixes as usual, some glorious resoldering and a few lines of 1's and 0's later...I have data! With my DAC working, both receive antennas are working and able to read the I/Q outputs!

Very pleased and now to turn this into something more understandable!

I'm slightly lazy; if I need to do repeated work I'd rather spend my time on building something that will do that job for me. (It's not always never faster but certainly more fun).

In the last few months I went completely overboard and built something that connects to, well, pretty much everything in my workshop that communicates. I can now control my power supply, read data from a power meter, read temperatures etc, all in a single tool. It can even control my 6-axis robot arm and watch and analyse my security camera's.

Using javascript, I can now run automated tests or whatever.

And of course, since it is 2026, I added AI which is pretty awesome. Combined with voice recognition and text-to-speech, I can now say " Set the power supply to 15V, 100 mA, turn the output on" while holding two probes. And it actually works. (Though first attempt it mishard it as 100 mA as 100 million 💀 So I built in a confirmation step). But AI can also write scripts for you and help to write the drivers to your equipment.

The camera and AI can also be used inside a script; imagine you have an old analog voltmeter and want to use the value to do something in your script: just point the camera at it and do something like

So I hope there are more fools like me who would love to play with something like this; if you want to give it a try, it's free! Though very much in Beta so I'm sure you'll find stuff I need to fix. Or stuff I need to explain better...

It should be able to connect to any scpi device over serial/usb or tcp/ip.
muxit.io has all the information and docs.muxit.io has even more.

You'll need to run your own local llm (like ollama or lm studio) to get the AI to work for now. I used lm studio with Qwen3.5 9b, which worked perfectly for recognizing images.
There will be versions in the future that have more advanced, integrated AI like claude and chatgpt but since that will cost me money I need to figure out how to get that implemented. The free version should be able to do all the cool stuff.

Let me know if you have any questions!

I thought this recent project of mine could inspire people on how to reuse the spindle motor on obsolete or crashed hard drives.

After all, it's a shame how these state-of-the-art motors often end up in the bin despite being in full working condition.

I built a so-called "ringing table" for microscopy by creating a drop-in replacement for the original disk controller on a twenty year old WD drive.

My board has a PIC processor, a three-phase spindle motor driver and a simple button-and-led user interface right where the SATA and Power connectors used to be.

It actually worked pretty well. There must be other things one can build from this basic concept! More technical details about the project are laid out on my personal blog.

https://espenandersen.no/ringing-table-from-a-dead-hard-drive/

I built a GPS and temperature data logger equipped with an alarm buzzer and an EEPROM for offline data backup and ESP32S3. I made a mistake with one net name but I was able to solve it.

Pd: How is the market in EE ? Is any opportunity for the new one?

Man the difference between linear and logarithmic pots and faders for volume is pretty interesting.

This is my third TX-6 style mixer that I had time to finally finish. The first used linear faders and pots, and the second had faders that were too high value resistance so it was more on the quiet side.

maybe it's time to start using PCBs

For more detail: https://blog.mehmetasaf.me/how-to-build-a-uart-to-half-duplex-converter-for-your-servo-projects/

Tomorrow, I will build this schematic on a breadboard. I might add some pictures later. Thanks for reading.