Category Archives: Alarm

This is the collection of alarm schematic diagrams at 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”.

12 Stage Water Level Indicator

The is a simple and versatile 12 stage water level indicator circuit which will show you the current water level in the tank. This circuit can be used for general purposes. This circuit generates an alarm when the water level is below the lowest level of L1 and also when the water just touching the… Read More »

Light Alarm with Timer 555

Here is the simple and low cost light alarm circuit built using timer IC 555 as the sound generator and a LDR to sense the environment light. This alarm is activated when the light beam on the LDR photocell is interrupted (You can use the light of a flashlight bulb which will make you a… Read More »

Car Audio System Anti Theft Security

This is the circuit diagram of car audio system anti theft security which can be effectively used to protect and secure your expensive car audio system from stealing. This simple circuit designed based on popular CMOS NAND chip CD4093,. When the circuit is switched on via switch S1, the indicator LED1 will glow and the… Read More »

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