Freeform Fun with Salvaged SMD LEDs

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.

7 survivors light

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.

9 salvaged LEDs

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.

SMD intro size comparison

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.

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