Examples of "time on" switches are oven and microwave oven timers, heater timers, clothes dryers and hot tub pump switches. The user turns a knob or presses buttons to adjust the desired time, presses "on," and the device works normally until the timer times out and turns off the device. The user can walk away with the assurance that the device will shut off. A variation on this is a motion-sensor security light, which senses an intruder and turns on an outside light until the timer times out again. A "time off" timer, also called a delay timer, waits until the preset time when it then turns something on.
Multifunction On Timer
This common timer switch is used for clothes washers and dishwashers to actuate and time a number of functions including filling and draining water, agitator wash time, spin cycles and even the automatic addition of bleach or softener.
Repeat Cycle Timer
A repeat cycle timer will turn a device or light on and off for preset adjustable intervals until it is commanded to stop the cycles. Examples are vacation light timers, air purifiers, pool filter controls and intermittent windshield wiper controls.
Percentage timers are used mostly in industry. An example would be to cycle a heating element on and off as a percentage of total time. So total time would be set for one-minute total time intervals. Then a setting of 40 percent for on time would mean that for each minute, the percentage timer switch would turn on a pump for 40 percent of 60 seconds, or 24 seconds. Then the pump would turn off for 60 minus 24 seconds, or 36 seconds. The next minute would begin and the pump would again come on for 24 seconds and then shut off for 36 seconds.
Favorite Timer Switch
Alarm clocks and clock radios are types of timer switches synchronized with real time. A very useful variation on the sound alarm is an electrical outlet on the back of some clock radios. Instead of sounding an alarm, a coffee maker can be plugged in to start brewing morning coffee on time to wake the soundest sleeper with the fresh aroma.