Alarm Circuits and Projects
Alarm circuits can be very simple or very complex, but most of them are made up of at least 3 parts:
- The sensor stage: These components can be of various types and are responsible for detecting the problem.
The problems can be detecting an intruder, smoke, high or low temperatures, inadequate levels of liquids, absence or presence of an object, etc.
- The trigger circuit: This part of the alarm is responsible for receiving the signal sent by the sensor, amplifying it to activate an output component such as a relay that in turn activates…
- An audio output device such as a siren, buzzer, bell, etc. or a visual output such as turning on lights, etc. It could also be an output that combines the two options.
- A fourth part, essential in an alarm system, is a Power source that in all cases must be accompanied by a backup rechargeable battery.
Some simple alarm circuits of various types are shown on this page.
Power failure alarm using transformer and relay
This power failure alarm circuit is very simple and is very useful when used with electric ovens, a refrigeration systems or to prevent a thief from cutting off the electrical power because it immediately warns of the problem. It also serves you when the fuses have blown.