[Ivan’s] friend built a proximity sensor to switch his LED bench lighting off each time he walked away. The idea is pretty neat, so [Ivan] chose to execute it for mains devices by making this proximity switched outlet box.

A Sharp GP2D12 infrared distance sensor is the essential to the system. It has an emitter and receiver that combine to give distance feedback base on how much of the light is reflected back to the detector. This is presented as a voltage curve which is monitored by an ATtiny85 (running the Arduino bootloader). It is small enough to fit inside the outlet box along with a tiny transformer and linear regulator to power to logic circuitry. The mains are switched with a relay using an NPN transistor to safeguard the chip’s I/O pins.

Check out the video after the break to see this in action. It ought to be a snap to add a count-down timer that gives you a bit much more freedom to relocation around the workshop. with that in place this is a fantastic alternative to some other auto-shutoff techniques for your bench outlets.