The Project:

This project has the aim to make a faster and safer way to turn off your lights in places like the kitchen and the bathroom, etc.. where you have wet hands and you want to turn ON and OFF the light switch.

This approach is also more hygenical because you don't actually touch the switch, thanks to the ultrasonic sensor.

The project can be extended also with a generical switch, because the circuit expose two pins, +12v and GND where you can attach your device. In the github repository you can find also the 3D printed case.

Description:

Sensor Light powered by a ultrasound module (HC-SR04) built on a chip. (SMD version). When the proximity sensor sees an obsacle (for example your hand) the relays are toggled (ON-OFF) / (OFF-OF) and the 12v powers the pins. The button triggers an interrupt (ATMega328P comes with D2 and D3 digital pin that can be used as interrupts, in this project only the D3 is used) that cycles 3 states:Relay 1 ON Relay 2 OFF

Relay 1 ON Relay 2 ON

Relay 1 OFF Relay 2 OFF

The project idea is to put two led strips in the pair of pins near the supply that can help you illuminate the kitchen/bathroom/other rooms. Leds can be replaced with all type of stuff you want but it hasn't to drain much current (Max around 0.1 amp), you have only to solder your device in place. Now are only supported devices without data pins, so you have to use only the VCC and GND.

Examples:

Some pictures of the Board inside the 3D printed case

And a short video that shows the behavior of the board