Category Archives: Alarm

This is the collection of alarm schematic diagrams at circuitdiagram.net. The alarm provides a warning tone when an event takes place, for example: thefts, fires, and other events that are not normal. Alarms have the capability of causing a fight-or-flight response in humans; a person under this mindset will panic and either flee the perceived danger or attempt to eliminate it, often ignoring rational thought in either case. A person in such a state can be characterised as “alarmed”.



Shutter Guard

This is the shutter guard circuit which has sensitive vibration sensor, piezo-sensor. This circuit is specifically designed for outlets to defend towards theft. It can recognize any mechanical or acoustic vibration in its area when somebody attempts to break the shutter and instantly turn on a lamp and sound an alert alarm. A 15-minute time… Read More »

Cheap Motorcycle Alarm

This is simple to build and cheap motorcycle alarm circuit which could be fitted in motorcycles to take care of them from getting stolen. The tiny circuit may be hidden anyplace, without having any difficult wiring. Practically, it fits all motorcycles as long as they’ve a electric battery. It is not going to drain out… Read More »

Heat Detector + Siren

This is the diagram of heat detector circuit which already integrated with siren circuit in the output. This circuit applies a complementary pair comprising NPN metallic transistor T1 (BC109) and PNP germanium transistor T2 (AC188) to detect heat (because of outbreak of fire, for example) in the area and activate a siren/alarm. The collector of… Read More »

Pyroelectric Fire Alarm System

This is definitely an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo component to recognize the fire. The lead zirconate titanate crystals within the piezo component have the property to deform and produce an electrical potential when heated, thus converting the piezo component into a heat sensor. The circuit mentioned… Read More »





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