Here follows a simple count down timer useful for the production of pcbs using photoresist and UV lamps. We have used a pic 16F887 Microchip microcontroller; there are no particular reasons, we have simply used the picmicros available at the moment.
Here follows the schematic (hex and sch downloadable, as usual, in the repository).
The countdown timer (1-9999 secs) is set by 4 buttons: reset, up, down, start. Naturally a relays is activate/disactivate during the counting.
For More Details : Count down timer, using a pic 16F887, for UV lamps