Security and Alarm

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 […]

In this article I have explained a few simple loop based security alarm circuits, categorized under closed loop, parallel loop, and series/parallel loop. All these designs could be customized and used for a variety of security alarm applications. Overview In a loop alarm circuit, more than one sensor is used, each one wired with a […]

The PIR burglar alarm explained here will detect a human intruder within the stipulated range and sound an alarm. Thus, the system could be effectively use for detecting trespassing, theft, intrusion, burglars, or any form of unlawful entry inside a restricted area or zone. Basic Principle The operating principle of the proposed burglar alarm circuit […]

This touch operated electronic door lock can be used for locking any entrance through a touch keypad. The lock’s touch feature is foolproof and impossible to crack since the touch function is required to be on 3 programmed pads together or simultaneously, otherwise the lock doesn’t respond. It is a lot convenient to open a […]

Gadgets and devices that are specially designed to repel or deter a potential male offensive can be used by a girl to protect herself from a crime situation, and therefore can be very handy. In this post I have explained a few of these devices which could be either purchased or even developed at home. […]