Soldering workshop: USB blinkenlights

project: , published: by Maarten Tromp.

With the experience gained from the last soldering workshop, I decided to do it all again once more.

At work we have a different workshop every month. Some workshops are work related, most are not. Soldering hasn't been covered by another workshop before and several colleagues liked the idea. Most of them had never soldered before and were willing to give it a try. A few already knew how to solder and that is exactly why they would like to join as well.

So I prepared for another soldering workshop. This time I designed a PCB to make building easier. No more figuring out the schematics or pining over perfboard layout. Along with the PCB I made an instruction sheet: Start with the smaller parts, work your way up to the bigger parts. An electrolytic capacitor is cylindrical, has both legs on one side and mind the polarity, etc.

The subject I choose is a classic: the astable multivibrator. No integrated circuits in this design, just two transistors and a bunch of passives. The unit has a USB connector for power and this nicely contrasts the old school circuit. Last, but not least, the unit has two clear red leds. They would blink alternatingly at about 1Hz. Where would we be without blinkenlights?

I managed to keep the costs lower than for the previous workshop. It worked out for under 5 Euro per kit. The boards were etched and cut by en electrical engineering student, offering a PCB etching service on his website. Parts came from my personal collection, so probably mostly from Ebay.

Even now, 3 years later, some colleagues still have the thing on their desk. Since then a couple new colleagues joined us, so maybe, one day, I might do a follow-up.