Reddit:Electronics

I’ll open with the project’s biggest criticism from everyone around me: yes this thing does require working SIM, which means money, which means the project has a recurring cost component.

It was built at the launch of Pacific Bell Mobile Services (PBMS) later Pacific Bell Wireless (PBW), Cingular and AT&T – the first GSM network on the west. As soon as I got the phone, texting immediately caught my eye. The project receives SMS commands and flips GPIOs to control a 24v Patlte tower via Opto22 – like those you see on a factory floor machines. Simple commands are texted to the phone number of the SIM inside the Wavecom module: yellow on/off, red on/off… and it replies with “done”. Now the Arduino context: the board is an early Futurelec ET-JRAVR with AT90S2313, firmware upload with PonyProg. Code you ask: Notepad and GNU GCC – hassle galore, however imagine the Star Wars-like magic of texting on your Nokia 3310; hitting send and in few seconds the tower lights up! Forget the dot-com crash; and S&P carnage. Just look at that cute little 1.9GHz GSM antenna (the only GSM band at the time), got it at Weird Stuff Warehouse.

And yes, I was a big fan (still am) of Opto22; I have boxes with hundreds of modules; love them yellow, white, black and red!

3D printing is such a fascinating field of technology, so a couple months ago, I decided to take a deep dive and learn how they actually work!

This took me to one of my very first PCB projects, a small, cheap, 3D printer motherboard. While it's not the most cutting edge board, I learned a lot and I fully documented my process designing it (https://github.com/KaiPereira/Cheetah-MX4-Mini/blob/master/J...), so other people can learn from my mistakes!

It runs off of an STM32H743 MCU, has 4 TMC stepsticks with UART/SPI configurations, sensorless/endstop homing, thermistor and fan ports, parallel, serial and TFT display connectors, bed and heater outputs and USB-C/SD Card printing, all in a small 80x90mm form factor with support for Marlin and Klipper!

Because it's smaller and cheaper than a typical motherboard, you can use it for smaller/more affordable printers, and other people can also reference the journal if they're making their own board!

If I were to make a V2, I would probably clean up the traces/layout of the PCB, pay more attention to trace size, stitching and fills, BOM optimize even further, and add another motor driver or two to the board. I also should've payed a bit more attention to how much current I would be drawing, and also the voltage ratings, because some of the parts are under-rated for the power.

I just got it running after a bit of bodging and I plan on using it to create a foldup printer I can bring to hackathons across the world!

The project is fully open source, and journaled, so if you'd like to check it out it's on GitHub (https://github.com/KaiPereira/Cheetah-MX4-Mini)!

I absolutely loved making this project and I'd love to hear what you guys would want to see in a V2!

This is a project that's been in the works for a while, I had been trying to find more compact and portable compute options for various projects and eventually settled on making my own carrier PCB for the CM5 which fullfills my needs. It's fully opensource so please do check it out!

https://github.com/azlan-works/Argo

https://oshwlab.com/azlan777/argo

When I tested this board I thought that I had designed it wrong, so I cut 19 traces (in the upper left corner) and rerouted them with patch wires. But it turned out that it was right from the beginning so I had to re-solder the newly added wires to restore the original configuration. A lot of soldering just to uglify the board...

Carpenters have this rule "Measure twice, cut once.", maybe electronics engineers should have something similar like "Test twice, don't patch" ;-)

WARNING! High voltage AC and DC on hot side of this circuit. Do NOT attempt to build any SMPS if you are a beginner. You need at least simple LCR meter and high-voltage oscilloscope probe for tuning. Caution is advised!

One of two higher power supplies that I need for my projects, this one is largest made by me. Transformer is a custom made also at home. Circuit and transformer design schematics in gallery.

Introducing Open-Schematics: largest public hardware schematic dataset, paired with images.

WIP screenshots for some RP2040 based cyberpunk sunglasses I've been working on this year.

Hopefully someone will one day create a kicad or easyeda extension that allows me to route at 30° / 60° angles, so I can make hexagonal traces

Third image is the first version. First and second images are improved based on feedback from my dad that has a lot more experience with electronics than me XD

This was possibly the most fun school project I have worked on, even if it was slightly more programming than wiring it all up

One of 4 Automated PCBA test fixtures I have just completed, entire design is from scratch and pretty much everything you see is 3D printed or Laser Cut!

I have 2x PCBAs inside, lots of wires and an additional switching PSU with Dummy load to simulate a battery for the UUT!

Hello, this is a radiophone project I'm working on while in my second year of ECE.

I came up with this new design this time on 4 layers as impedances are really smaller.

First part of the circuit (bottom left) is an LC that will tune close to 1Mhz using an old-school variable capacitor. On next the signal gets demodulated, amplified, given power and outputted (bottom middle) and the rest is a simple power rectifier, with an IC for a cool volume bar using LEDs

Pics are in order of layers, I used GND/SIGNAL - GND - POWER / SIGNAL - GND, and keepout zone below the transformer in order to remove capacitive noise.

Schematics

Layer 1 gnd/signal

Layer 2 GND

Layer 3 power/signal

Layer 4 gnd

This is a small laser module built utilizing a laser diode recovered from a DVD burner. The power supply is based on a ST Microelectronics LM317T adjustable voltage regulator set up in a constant current configuration.

Picture 3 is the output next to a ~5mw laser pointer output. don't think my phone camera liked taking this picture.

Schematic included.

Why the F did they decide to. No, no lissen, we need 36 different pinouts on the same ic with no id code on it either making it impossible to know wich "style" ic you got. Now that's what we need. Looking for help to identify GDS on the nmos somehow cuircit or instrument no problem.

I recently assembled a rosco_m68k tht kit version. Took around 4 hours, tried to keep everything as clean and careful as possible.

Ironically, I’m also working on my own soldering-related project called SolderDemon, so this failure was a good reminder that even clean work can hide stupid problems.

After powering it on, the board wouldn’t boot. Only the START and RESET LEDs were on. Measuring the CPU RESET pin showed ~2V, which made no sense.

First suspect was the RESET button, I desoldered it completely. No change.

While reflashing the PLD, I finally noticed the real issue: one of the IC sockets had a bad pin. The chip looked seated properly, but that pin wasn’t making contact at all.

I fixed the contact temporarily just to test it and the system booted immediately.

Lesson learned: don’t just inspect solder joints. Check IC socket pins too.
Even when the board looks clean, a single bad contact can make a system look completely dead.