Connect the Power Synchro Relay to the power cord of the projector and the RF-IR converter to the screen to create a synchronized control system. The Power Synchro Relay is designed for projectors that do not have trigger outputs. It detects the power current of the projector and transmits a wireless signal to the receiver. When the projector is turned on, the projection screen will automatically lower. When the projector is turned off, the projection screen will automatically retract.