Alarm Circuits

This Simple Light Activated Alarm Circuit is like very sharp nightlight. It have small part called LDR which work like a tiny eye. When light goes away fast like someone is moving near circuit it make sound or light happen to warn us. It also uses other parts like transistors, resistors, capacitors to make it […]

Simple Freezer Alarm with Buzzer Circuit is like small guard for our ice food. It uses one sensor, thermistor to check cold level. If freezer become warm too much then buzzer makes loud sound to tell us something is not right. Like food is going to melt. With this indication we can do something fast […]

Simple High Temperature Alarm Circuit using IC 555 uses one special chip called IC 555 which works like a temperature guard. It keep checking temperature always. If its too much hot it make alarm sound like buzzer and tell us something is getting too hot. So we can know early and fix before big problem […]

This easy and Simple Entrance Alarm Circuit is made to protect door or way where people enter. It makes loud sound when someone walk through invisible IR light. It works good at day and night by not giving much wrong alarm. The circuit is simple and good for hobby people during nighttime. Circuit Working: Parts […]

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 […]