This is a very simple touch sensor switch that is build with the 555 timer IC. You just need to touch the metal plate and the relay gets energised and is kept in this state for about 100 seconds, then ...

This article explains an upgraded smart solid-state AC switch system that uses microwave Doppler radar instead of traditional PIR sensors.

Capacitive touch sensors are entirely in the domain of DIY, requiring little more than a carefully-chosen conductive surface and a microcontroller. This led [John Phillips] to ask why not embed such ...