I would like to build a dispenser to give my dog a treat automatically when she drops a toy in a box. I have a treat dispenser that moves easily and can be attached to a pulley. I don't have the electronic know-how to make the rest. I am thinking a motion sensor light or driveway warning unit that sends a signal when a beam is broken could be used, but don't know how to connect it to a small motor that will only run for a couple of seconds and then stop. Any thoughts on how to do this and where I might get the equipment?