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.