In this post I have explained the working of 3 interesting and useful temperature alarm circuits through detailed circuit diagrams. A temperature alarm circuit is basically a device which is designed to detect a temperature threshold and sound an alarm as soon the temperature exceeds over, or drops below the desired temperature detection threshold. 1) […]
Alarm
Door Security Alarm Circuit for Alerting if Door was Opened
The door security alarm circuit discussed in this article alerts the user whenever the door fitted with the circuit is opened or closed or even moved from its original locked position. Using a Reed Relay and Magnet for the Triggering The idea utilizes the very basic reed relay and magnet concept across the door and […]
Touch Alarm Circuit
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 […]
Simple Anti-Theft Alarm Circuit to Protect Valuable Items
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 […]
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 […]