This circuit is based on a passive infrared PIR sensor, which automatically switches on a device when someone comes close to it. For the full list of timer-based projects check out timer projects. Here, we take a look at some timer circuits based on the IC. Be it a simple timer project involving a single 8-bit micro-controller and some peripherals or a complex one involving system on chips SoCstimer working is involved. The timer IC is an integral part of electronics projects. It can be used to provide time delays, as oscillators and as flip-flop elements. The standard timer IC is used in a variety of timer, pulse generation and oscillator applications.