This is a demo of adding some extra circuitry and functionality to an existing product in relatively clean way, in this case an old Macintosh Classic. I added the ability to turn the screen off and on with a keyfob RF remote. One looking at the finished product cannot tell that it was previously opened and hacked.
For this test, I used a keyfob remote and RF receiver from Adafruit, and a relay module from SainSmart. When the receiver gets the keypress command from the remote it toggles the voltage at a pin which in turn toggles the state of the relay. The relay shorts the wiper pin of the pot to the lower potential pin of the pot. This particular pot for the brightness adjustment has about 600V across it’s terminals, unlike the vertical adjustment pot for example which has 7V across it’s terminals. When the relay shorts these connections, it has a similar effect to the pot being manually turned all the way to that extreme, in this case turning the brightness all the way down and effectively turning the screen off. With this setup the keyfob remote can turn the screen on and off wirelessly.