This project is available at: Sound Operated Timer. A single side PCB layout for the sound operated timer and its component layout is also provided. It can also be used as a sound sensitive burglar alarm. Time delay can be set from a few seconds to 30 minutes. This sound operated timer is based on LM324 quad-operational amplifier and NE555 timer. This 555 timer circuit is available at: Motion Detector using NE555 Timer. Applications of this circuit include security systems, corridor lights and bathroom lights among others. It can also turn on lights when someone approaches the area where it is installed. It can be used for detection of theft or an unauthorized person entering a restricted area or building. 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 555 timer projects. Here, we take a look at some 555 timer circuits based on the IC. Be it a simple 555 timer project involving a single 8-bit micro-controller and some peripherals or a complex one involving system on chips (SoCs), 555 timer working is involved. The 555 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 555 timer IC is used in a variety of timer, pulse generation and oscillator applications.