There’s a freeform circuit contest going on at Hackaday right now. I’m not eligible to enter, but I can still have fun on my own. I haven’t had any experience creating freeform circuit sculptures and now is as good as time as any to play around for a bit.
Where should I start? The sensible thing is to start simple with a few large through-hole light-emitting diodes (LEDs), but I didn’t do that. I decided to start higher up on the difficulty scale because of a few other events. The first is that I learned to salvage surface mount devices (SMD) from circuit boards with a cheap hot air gun originally designed for paint stripping. I had pulled a few SMD LEDs from a retired landline telephone and they were sitting in a jar.
The second is the arrival of a fine soldering iron tip. I had ordered it in anticipation for trying to repair a damaged ESP32 module. I thought I should practice using these new tips on something expendable before tackling an actual project, and a freeform exercise with salvaged SMD LED seems like a great opportunity to do so.
As a beginner at free form soldering, and a beginner at SMD soldering, the results were predictably terrible. I will win no prizes for fine workmanship here! But everyone has to start somewhere, and there will be many opportunities for practice in the future.
It’s just a simple circuit with seven LEDs in parallel, on the lead of their shared current-limiting resistor. Not visible here is another aspect of learning to work with surface mount components: they are really, really small. I had actually salvaged nine LEDs. Two of the nine LEDs have flown off somewhere in my workshop and didn’t make it to the final product.
For comparison, here is the “I ❤ SMD” soldering kit that was my gentle introduction to surface mount soldering. The LED in that soldering kit were significantly larger and easier to manipulate than those I salvaged from an obsolete landline telephone.
Moral of the story: for future projects practicing SMD assembly, be sure to have spare components on hand to replace those that fly off into space.