12V Relay with Timer Switch

Written by: admin@makezilla

In this Instructable, we'll be learning how to use a timer switch and a 12V relay to control the extension of an Actuator. You'll be able to set the timer with up to 17 time schedules, and have the actuator extend and retract when the time is right.

No coding is required, all control comes from the timer. Any 12V power supply can be used, as long as it can deliver the current that the actuator requires (5A minimum suggested).

For this project, you will need:

- 1 x 12v Relay

- 1 x Digital Timer

- 1 x 12V battery

Step 1: Wiring the Relay

Wiring the relay creates a half bridge. When 12V is applied to Pin 8, the relay will activate. Wiring the relay as shown will cause the voltage across Pins 5 and 6 to change from -12V to +12V. The default position of the relay is when the relay is deactivated, the active position is when Pin 8 has 12V on it. The actuator can be wired in 2 ways. One way, the default position is extended, and the timer controls retraction. The other way, the default position is retracted, and the timer controls extension. For this example we're using retracted as default and extended when the relay activates. To change the actuators position when the relay is deactivated, switch the wires on Pins 5 and 6.

Wire the relay as follows:

- Connect Pin 1 to Pin 4

- Connect Pin 4 to +12V

- Connect Pin 2 to Pin 3

- Connect Pin 3 to Pin 7

- Connect Pin 7 to GND

- Connect the two wires of the actuator to Pins 5 and 6, so when the relay is deactivated, the actuator is retracted. If the relay extends, just flip the connections on 5 and 6.

See the wiring diagram for details.