Looking for a fun and easy way to add a bit more interaction to your LED-laden projects? Why not turn them into proximity sensing LEDs? Our hacker, [Will], is just getting into designing his own PCBs.

Back in the late 1960's, I experimented with DTL. That's not a misprint. DTL stands for diode-transistor logic and it was popular in “930-series” logic devices. I used wire-wrap or point-to-point ...