I repair hearing aids now, but used to repair computer graphic systems for Lundy Electronics & Systems, before that it was automobile radio repair (too old for that now.) When I went to electronic school there were no PCs, we had to trace signals through logic boards, TTL and magnetic bead memory. Think UNIVAC but I've picked up a few tricks with PCs. I enjoy art, think LEDs are cool. On hearing aids, I stay away from Behind the Ear models BTEs, they are too tightly packed, have one of a kind parts except for microphones and some receivers, lots of corrosion in them too. I stay away from flex circuits mostly too, hard to fix, easy to destroy. Try not to drink much coffee if you need to solder in a rice sized microphone! I like the fact that with a small hearing aid, the trouble is right there in your hand, you don't have to look far for it.