One of the more niche electronics scenes I love to follow is
#Badgelife. It’s a dedicated group of people who create electronics badges (usually palm-sized) that can be anywhere from passive decorative art to full-on video game emulator systems waiting to be hacked. Most of these end up being in the infosec community for whatever reason - likely due to the size of the scene? Regardless, I’ve been doing my best to contribute, but mostly from an outreach/advocacy point of view. I’ve had lots of fun opportunities to do this in college, but none since then really.
Luckily, I invented one. I got permission to whip up a batch as a work holiday gift, and man was it awesome! It took about 15-20 hours of total work from idea to getting them into everyone’s hand, so totally worth it. I wanted to stretch my artistic side a little bit, so I got to have some fun on the silkscreen side. There’s no real theme, or rather, there’s two utterly disjointed themes - Christmas and Astranis. I very briefly thought about making it Alaska related somehow, but eh, too much coherent though for an impulse project. The design files are after the pictures.
I learned some interesting things making this:
- My coworkers are not too good at soldering =)
- This “basic” 555 LED Fading circuit has some neat subtleties. When I first got it back, it would just stay on the entire time and I had no idea why! Ended up being a rather neat bug: If R1 (RC timer resistor) is too large, the voltage drop across it is quite meaningful. This current drop is primarily due to the input base current of the BJT, which in our case was ~100 uA. This meant we never hit the high side of hysteresis point, and the circuit just stays in an on-state. This occurred because I thought using massive electrolytics was silly, let’s just use a larger resistor. Well, I only have myself to blame =)
- Backlighting LEDs is a really beautiful effect. I deliberately chose diffused LEDs to not blind people. Then I saw some examples online where shine the LED through the FR4/fiberglass to get an even nicer effect - genius! Loved how it came out here, and I’m going to use it more often in the future.
We ended up having a mini “make-your-own” workshop and it went great! Here’s one of the finished ones:
If you want to copy it, go for it! If the Altium files are a problem, happy to output in some other format if it’s not too much work - feel free to email me. Please note that there’s two (rather large) bugs in the current design.
- Pins 1, 8 on the 555 timer are backwards. These are
GND. Oh well, midnight PCBing is dangerous. Jumper wire solves it alL!
- The drilled out vias for the battery leads are far too small. We made it work with poor soldering technique and super glue, but I just recommend making them bigger.