time switch 
noun
A switch automatically activated at a preset time.The photoperiod was controlled by a manually operated black-out facility in the poly-tunnel, and by automatic time switches in the cabinets....
- As well as targeting known criminals in the area, police are providing discounted safety locks, personal attack alarms, time switches and low-energy bulbs.
- The Pakistani government said during the raid in which the six were caught, authorities found 330 pounds of high explosives, detonators, transmitters, time switches, arms and ammunition.