I make this timer several years ago, when I move in to where I write this.

The bathroom has not window, but a small ventilator with long pipe, and the ventilator share the power line with the light. 

So, when I need to vent the moisture, I had to turn the light on for hours and wasted lots of power. I don't think that's good to our earth. 

To keep safe, I use no-touch photo sensor to control the timer. and a optional fan is add, to accelerate the drying.


The circuit schema timer.sch can open by ExpressSCH program


When light on the Vent. on too, but fan off, so you won't feel uncomfortable when naked :)

When light off, the fan on for 1 minute, when both vent. and fan off.

When light on, you can control the timer by waving over the photo sensor to break the light, the LED will on to indicate the timer setting, as 30 - 60 - 120 - 180 minutes and repeated

After setting the timer, when light off, 3 seconds late,  the fan on too, and the clock ticking, the LED flashing, when timeout all off

When the clock ticking, and the light on, the fan stop, and the timer pause, until light off.

Any photo transistor will done, my came from a dead "mouse", a rolling encoder have 4 photo sensor.

Mount the timer at somewhere dark but direct  illuminated when light on, direct the photo sensor to the light. of course, keep away from water.     

This firmware is for 60 Hz AC power line. IF for 50 Hz, change "Hz EQU D'60'" to "Hz EQU D'50'" in the ASM file, and do assembly again to get a 50Hz .HEX file. 

PIC16f84A.ASM                                  PIC16F84A.HEX



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