Homemade watchwinder. 2011-09-17

My father owns an old automatic watch from the 1960's that he often uses. If the watch is not used for more than one day it stops and needs to be set again. I built this watchwinder for him so the watch always runs as it should.

It's based on a PIC12f675 and a simple H-bridge made by old BD139/140 transistors to reverse motor polarity. The PIC is probably overkill for this project but they are so cheap and easy to use.

The box is built of plywood which has been coloured brown and then clear coated for the "right" finish. For test purpose i use my cheap Casio G shock watch.

Electric motor controller. 2011

The assigment was to build a motor driver that shifted the rotation in specific sequence. It was specified for 12V and 2A. The small motor in the picture was only for testing and not the actual motor used later in the prototype.

"Silent" audio amplifier. 2011

Many years ago I built an 2,1 amplifier that I still use sometimes. It was rated 2x15Wrms and 100Wrms for subwoofer. I use this amp in my gym. 

Last time i started it the subwoofer was silent. The amp is NOT service friendly and my schematics were really bad and missing a lot. It was hard to follow the signalpath due to bad documentation. Finally I revealed that a OP-circuit which was part of the subwoofer filter was dead. Changing this fixed the issue.