Security and Alarm

In this post I have explained 3 simple yet accurate infrared intruder alarm circuits using an infrared transmitter and an infrared receiver module. The transmitter and the receiver photo diodes used in the two modules are aligned in line at a distance of around 2 meters within the restricted area. When a burglar tries to […]

In this post I have explained how to use IC 555 to create 7 interesting siren and alarm sound effect generator circuits. The versatile astable multivbrator configuration of IC 555 allows us to implement it for making various types of sirens and alarm circuits. This becomes possible because an astable is basically a waveform generator, […]

This easy yet useful security alarm circuit is designed to get triggered in response to even a brief movement of the unit, causing a loud alarm sound to set off. The circuit could be attached or installed on any desired gadget or asset which needs to be protected from theft. As soon as the gadget […]

A laser microphone is a security monitoring gadget in which a laser beam is used for detecting audio vibrations across faraway targets, which are normally walls or glass of homes or offices. These devices could be applied for eavesdropping with virtually no chance of getting identified or cover getting blown. Laser eavesdropping gadgets, it is […]

The touch alarm circuit senses the mains hum signal from an intruder’s body and raises the alarm sound. This happens whenever an intruder touches a potential element set as the sensor, such as the door knob, or any object that needs to be protected. If the circuit is linked with the door knob, the circuit […]

The simple ultrasonic fire alarm circuit I have explained below detects a fire hazard situation by picking up the variations in the surrounding air waves, or the air turbulence. The high sensitivity of the circuit ensures that even the slightest of air turbulence created by a temperature difference or fire is quickly detected and an […]