Reddit:Electronics

I've been building an open-source embedded systems simulator called Velxio.

It supports:

• Arduino, ESP32, Raspberry Pi Pico and Raspberry Pi emulation
• Multi-board systems communicating over UART, I2C and SPI
• SPICE-based analog circuit simulation with ngspice
• Retro CPUs including Z80, Intel 8080, 4004 and 8086
• MicroSD and ePaper emulation
• An AI agent that can generate circuits and firmware from natural language

Everything runs directly in the browser. No installation, no account required.

You can try it at http://velxio.dev

A regular poster here exhorted us to reduce tantalum usage, especially now that X5U ceramic capacitors are so good.

Here's link showing how some of that tantalum is mined, and the associated landslides:

https://www.bellingcat.com/news/africa/2026/05/12/congos-coltan-belt-verifying-deadly-landslides-at-mines-under-m23-control/

I have some nimo tubes, so i'm just showcasing them here.

About a month ago I posted my credit-card sized computer project here and was honestly overwhelmed by the response - and thanks for all the encouraging feedback, that really helped a lot!

One thing that came up repeatedly was people asking how it was actually built, so here I have some more details on the actual process. It's actually a bit of a hassle to take photos while working with dangerous chemicals, but it was worth it for sure!

Honestly, my first thought after seeng this first picture was like "dang, this is nowhere as clean as I thought..." to the naked eye, everything looks precise and flawless, until you take photos with macro lens mounted on a mirrorless camera. But honestly, this kind of is satisfying too: Not only you can see all the impurities, but also every single overflow of solder paste, which doesn't even look like paste anymore as you can see the microscopic solder balls swimming in flux.

Some areas needed some manual rework with additional solder paste, and the bridge over there was a result of my single layer limitation for now. And yes, I see it's almost shorting with another net but it luckily turned out fine.

And regarding the actual etching process, that was described in my GitHub repo, but it was basically the normal method of etching PCBs with the difference of using copper foil with kapton tape as substrate. Curing the photoresist layer, developing it with a 5% sodium carbonate solution, etching it with ferric chloride, and lastly stripping the remaining photoresist with a 2% sodium hydroxide solution. Optionally solder mask if needed, but I skipped that step with this one.

It's somewhat workable to get fast iterations but has the drawbacks of being extremely fragile. On some photos you can see how uneven the PCB is even though I taped it stretched onto a flat, rigid surface.

Note that the pictures of each step is made on different runs, so you might spot some differences as result of trying different techniques. I already ordered a proper PCB from a fab, once that arrives, the Muxcard will be actually durable enough to be used as a daily driver.

And for those who asked: Yes, I do plan to launch this soon. And if you're interested, you can find more details on the GitHub page :)

But this post is more about these cool pictures I wanted to share here first, I'll add them into the repo as well as reddit doesn't seem to support including pictures in the text body.

If there's anything you're curious about, feel free to ask - I'll try my best to answer every comment! :)

Sound meter with tower light and projector message device for classroom a teacher is buying

I am really autistic about the precision of temperature in my projects, and I found a cheap toaster oven for 14$ the perfect size for my work space, decided to replace the bimetallic thermostat with custom electronics and control circuitry, it was an amazingly fun project!

hope you all enjoy this dumb project! and remember, if you mess with 120V BE CAREFUL!

programming listed on github,
video of process posted to youtube

https://github.com/EleriLove/pwm-pid-control-of-relay-

https://youtu.be/Qr83flDN-Bk

I have a long standing fascination with nixie tubes and wanted to build something for a while.

I got this board of aliexpress with only basic clock and i simply could not waste it to leave at that so I have reverse engineered connections and disabled on board chip.

I have replaced boring stm chip with esp32 and now have a cool looking clock with functions like:

Timer, stopwatch, reminders, alarms, navidrom music player, adjustable RGB, wifi ntp sync etc.

All controlled via backed web-ui

I’ve been working on a custom Arduino wireless remote using an NRF24L01 module and a rotary encoder.

The photos show how the project evolved from a breadboard prototype to a fully soldered perfboard version.

The next step is adding an I2C LCD and refining the software.

I’d love to hear any suggestions or ideas before I move on to the next revision. What would you add or change?

I made up a schematic of the division unit for my recent calculator project, with some adjustments. I switched out a few chips with ones from the same family, but I tried to keep it as close to the original as I could. The original also only took 7 bits for the divisor as it only took up to 99 as an input due to the interface of the calculator. Definitely could be optimized.

This is my first time translating a circuit of this size to a schematic, so it might be... messy. Hopefully I didn't miss anything; I checked it over a few times. A few adjustments might be required.

"Start" must remain low until dividend and divisor are inputted. This signal must remain high until the XOR signal, from carryout and OR, is high, which then tells the circuit that the result is negative and to stop subtracting the divisor.

I have a video of the division unit from when i was still testing it as well. I plan and am working on creating a whole schematic of my calculator without any changes, but do beware that my demonstration of the unit isn't 1:1 as it's from early on in testing, same with the second photo. https://youtu.be/GKElo5Bfb7c

First time trying something like this!

I'm a high school student who has an interest in point clouds and spatial data, so I made my own LiDAR scanner! This was my first time making a PCB, and the scanner runs on an esp32 & TMC2209 stepper drivers. You can see my Github with the KiCAD project files here.

As one of like 3 people who absolutely loves cat whiskers when I stumbled upon a paper from the 1920s known as “the Crystodyne principle” I got real excited, then I realized I don’t own zincite and ya I know the paper itself says you can use galena and fools gold but I’ve over used fools gold and if I’m gonna buy galena why not spend that money on zincite, but then I had a genius idea “what if I made the crystal!” So then I got to work (spent like 5minutes finding out how zincite forms) and discovered it’s just the mineral equivalent to zinc oxide so I heat treated some zinc WITH A MASK NO ONE WANTS ZINC PLATED LUNGS, and to my surprise it worked 2nd try. The hardest part had to be actually making the circuit because “the Crystodyne principle” doesn’t tell you how to make an amplifier only that you can so like any responsible science fella I just started shoving crap together based on half complete knowledge till it worked and then when I got it to work I needed to figure out how to A. Remove unnecessary components B. Increase volume C. Decrease static. And this is the circuit I came up with. To test it I put the earpiece in my ear under a pair of headphones and tapped the mic against an auto transformer. I also managed to use it to amplify an electric kazoo.

Je travail sur un projet d'arrosage de plante autonome souhaite moi bonne chance 😂😉

All thanks to one single person who believed in me & pushed me to do it!

Yesterday I started up an old Soviet gas discharge rectifier ВГ-176.

Fixed a couple of old broken carriage clock recently with some STM32s, e-displays & some bling.

Setup:
* Microcontroller - NUCLEO_L432KC
* Display - Waveshare 2.9" & 3.7" E-Paper Displays
* Sensor - DHT Temperature & Humidity Sensor with 100k pull-up resistor between the 3.3V rail and the DATA/OUT line.
* Power - Voltage Regulator HT7333 and Micro USB 18650 Lithium Battery Charger Module
* Bling - Some pencil art with gold surround, gold run on transfers & corner protector gold filigree