New Project: Switch-Programmable Blinker

Partially assembled programmable blinker (top)

Partially assembled programmable blinker (bottom)

Earlier I made a waterfall LED circuit from a DIY kit, which used a counter and transistors to sequentially light up arrays of LEDs. I had an idea to take the same basic design, and add in switches, so one could program which LED array gets switched on in each step of the counter, just by adjusting the switches. In this design, there are three arrays of LEDs of different color, and an 8 step counter, so one could have some fun making the colors blink to a quarter-time rhythm. Probably that idea is nothing SpaceX will want to buy out, but I thought it would be fun for my next DIY PCB design project.

I'm using a lot more SMT components this time to save board space. That includes SOT23 transistors and diodes, and 1206 resistors. In retrospect, I'm wishing that I had went with SMT LEDs also, as that would have made the trace layout easier.

I have to admit that hand-soldering SOT23 components is not easy - the biggest challenge is getting the first leg done without messing up the positioning of the component. It is also difficult to make the solder joints look good, although I think it would turn out better if I had some of the ultra fine 0.4mm solder, rather than the 0.6mm solder I am currently using.

I understand that using the solder paste method is supposed to be easier, but I'm still hesistant to go that route. My understanding is that the paste is rather expensive and doesn't last a long time. But maybe I'll give that a try sometime in 2022, God willing.