Connecting a Relay to the RPC Motion Sensor
To use our motion sensor to control motors, pumps or solenoids you need an additional "slave relay".
The more robust contact of this relay, which must be supplied from a separate suitably protected heavier circuit (see diagram), will then operate the larger load.
Never connect heavy loads to the sensor directly.
Because the slave relay coil is what is called an "inductive" device, a catch diode should be wired in parallel across the relay coil; and it must connect a certain way, or the fuse will blow first time you put it in.
Before you start, ensure that the battery voltage matches the sensor's and the relay's voltage. We sell both 12 volt and 24 volt motion sensors.
- Connect (any) one of the sensor's red cables to the battery positive. Protect this connection with a 10 Amp fuse. Remove fuse for now. (Here's a nice weatherproof fuse holder, if you don't have one yet.)
- Connect one blue cable to the (now fused) red supply cable using a link (short bit of wire) that bridges the two screw terminals (inside the sensor).
- Connect the other blue cable to one of the relay switching coil terminals.
- Connect the other relay switching coil terminal to the battery negative.
- Connect the catch diode across the relay coil.
- Connect the battery negative to the sensor's other red cable.
- Place fuse back in holder. Now you should hear a click in the relay when motion is detected.
- Connect your load to the relay switch and battery (with appropriate fuse) as shown in diagram.