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 […]
Security and Alarm
Ultrasonic Fire Alarm Circuit using Air Turbulence Detection
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 […]
Loop-Alarm Circuits – Closed-Loop, Parallel-Loop, Series/Parallel-Loop
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 […]
PIR Burglar Alarm Circuit
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 […]
Touch Operated Code Lock Switch 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 to Protect Women from Assaults and Harassment
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. […]