Setter's device, one casting spell on our readers?

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ A time switch can accurately control the photoperiod. ▪ A time switch disconnects the heating coil after it has had time to warm the lock. ▪ A time switch is useful, but not essential. ▪ If an automatic time switch is available, ...

Wikipedia Word definitions in Wikipedia
A time switch (also called a timer switch , or simply timer ) is a timer that operates an electric switch controlled by the timing mechanism . The switch may be connected to a electric circuit operating from mains power , including via a relay or contactor ...