I have a requirement for an unusual electrical gadget that is IF it exists. What I need is a timed switch that I could use to turn on and off the power supply to another electrical devise at regular increments. I would like to be able to set it to have the power come on for one minute every 5,10 or 15 minutes. I have seen the switches for leaving your house lights on when you are out of town, but it cannot open and close as frequently as I need. Anyone know of such a device that would fit the billing? The application is photographically related to the darkroom.

Thanks in advance!