Wireless Projector Remote

A few years ago, we installed a projector in the church sanctuary. It is mounted to the front of an exposed truss, and the laptop that controls the video display is in the back of the sanctuary. The problem is that to turn the projector on or off, someone always needed to go to the front of the sanctuary and point the remote at the projector, which is not ideal.

This is my attempt at solving that problem. The idea is that instead of using an infrared signal from the back of the sanctuary, we'd have a key fob RF transmitter that would send a signal to a receiver. The battery-powered receiver would be placed somewhere at the front, pointed at the projector, and would translate the RF signal to the IR on/off remote commands that the projector understands.

Design features:

• 315 MHz on/off-keyed signal
• Low-power receiver powered by 2 AAA batteries (should last several months on one charge)
• Key fob transmitter powered by a CR2032 cell
• Separate on and off commands, keyed to two buttons on the transmitter

Project status

The RF transmitter and receiver circuits work to the point where I can get good carrier wave detection at about 30 feet.

The receiver, however, consumes way too much battery power, because the inductor I used for the boost regulator doesn't have a high enough saturation current. The bill of materials (below) reflects this change in the receiver component L2. I have not resized the land pattern on the board yet - it's still sized for an 0805 component.

The project has since been abandoned, because we now have a new projector with a remote powerful enough to bounce off of the front wall.