Timer for PCB exposure box with ATtiny2313
When doing more than one thing at the same time it is very easy to lose track of time. Exposing PCBs to UV light is delicate work and overexposing will result in, well, you know what.
Exposing is usually done with UV fluo-tubes but compact fluorescent lamps are also safe way to go and result in excellent PCB quality. Housing for the exposure system shouldn't be a problem because those old broken PC scanners come very cheap. The only thing missing here is the timer to turn off those lamps after pre-set (experimentally determined) time, but this also is not a problem any more because this solution with ATtiny2313 is excellent!
[ Source: Darkroom timer for PCB exposure ]
[ Source: Kizo ]