This is a RC switch that is activated by a RC signal.  A RC receiver ouputs a 1.5ms pulse every 20ms for center stick, about 2ms pulse for a full forward stick posigin every 20ms and about 1ms pulse ever 20ms for a full reverse stick position.  A preprogrammed microcontroller is used to read these pulses and drive the relay.  When the stick is in center the relays will be off, when the stick is about 1/3 up one relay will pull in resulting in the load going one direction, then the stick is about 1/3 down both relays will pull in resulting in the load going the other direction.  To change the direction you can reverse the leads of the load on the board or reverse the transmitter.

This board is set up to drive a load forward and reverse.  Close the the single pole relay and the load goes one way, close both relays and the load reverse, the load is off when not relays are pulled in.   It also include travel limit switch inputs to stop the motor/load when the limit is reached.  There are two limits, one for each direction.   If you don't want to use the limits, just jumper them.   The circuit also has inductive load transient suppression which occurs when driving such things as coils on relays. 

The board has a status LED which will light when the relays are pulled in.  It also has a yellow LED for the status of the signal.  A solid yellow means the board is receiving a good signal in center stick (1.5ms pulse ever 20ms).   If the yellow light is off, the stick is not centered, if the light if blinking rapidly, there is no RC signal detected.   The board relays are rated at 8A@120VAC.    A 5V power source is required to drive the relays.  You can use the power from the receiver for this.  Another input voltage is required to drive the motor/load.

If you want screw terminals as pictured, you must select that addition below, else you can solder your wires right into the holes on the PCB.  ou can also opt for a RC male plug to plug this board directly into your RC receiver

These kits come unassembled, but you can opt for assembly if you wish.  All the components are on the top side, and the boards are spaced out to make assembly as easy as possible.  Click on the images to view the board in detail.

For assembly and operation instructions follow this link.(~1.5MB)