For valentines day I stayed up late the night before and made a small and very simple LED heart chip. It’s composed of 14 LED’s arranged in a heart shape attached to an old wall wart. I ran into three strange hiccups that turned this 30 minute project into a 3 hour one.
1. Cutting perf-board without a Dremel (couldn’t find the adapter for mine) is like trying to cut through half a ream of paper with baby scissors.
2. That old wall wart I used as a power supply was unregulated and wavered unevenly by almost 2v (this turned out to be a plus eventually).
3. Work out the voltages and connections before you twist 40v worth of LED’s together, nothing produces exactly 40v.
The perf-board problem was resolved by just using the soldering iron to widen and weaken a row of holes, followed by cutting through it with normal scissors, then sanding it off afterwards. The LED voltage problem I solved by dividing the LED’s into two halves, left and right. Unfortunately when testing the right half I accidentally fed it 36v instead of 24v and blew out the entire half (had to tell my girlfriend that only half the heart lit up because it symbolized us sharing a heart). The most interesting thing about this entire project was that I picked out an unreliable PSU and ended up with a source that wavered by 2v at about 80BPM, coincidentally this is an average resting human heart rate. When I wired it all up the left half would beat like a heart, speeding up when you first plugged it in, then leveling out, then slowing when you unplugged it before finally flatlining when the capacitors run out of charge. All in all, well-spent time for a great Valentines day gift.