Alarm Circuits

This Smoke Alarm Circuit is like house that has got a big nose. This circuit smells smoke in air and if smoke come it make loud alarm sound. Alarm can be buzzer, blinking light or it can be other alarm to start also. Smoke detector can work in different way one can use small light […]

This Simple Shadow Detector Security Circuit is like one guard with very sharp eyes. It uses one light sensor like photodiode to look shadow in one place. If something stop the light and make shadow then the circuit think someone is there and start an alarm. Alarm can be loud sound, blinking light or something […]

Ultrasonic Security Alarm Circuit work like invisible wall for ones home. It uses very high sound wave like tiny squeaky noise which human ear can not hear it uses this to find the movement. Think like circuit sends sound wave then it waits to hear echo come back. If someone walk in the way and […]

This Infrared Alarm Barrier Circuit show how to use light which we cannot see to make tripwire alarm. It work like beam of light for small fences. When someone walk in front of light and break it, loud alarm make big noise to warn and scare person. It is fun project to do but real […]