Posted by Circuits Arena on Tuesday, 20 February 2018
How to Make Burglar Alarm Circuit by using timer IC 555 is the artlcle explaining Burglar Alarm Circuit The circuit shown here is used as a burglary alarm. LDR is kept in such a place that when the thief enters our ho...
Burglar Alarm Circuit
The
circuit shown here is used as a burglary alarm.
LDR is kept in such a place that when the thief enters our house, a shadow falls on the
LDR. A small beam of light is also needed to deliver an uninterrupted signal to the LDR. To obtain the best light source, we can use a laser diode that works for a few kilometers. For home use, the infrared
LEDs will be good and it will be difficult for thieves to work with the same efficiency at night.
This circuit uses a popular timer IC, which is 555.
IC 555 is connected as a comparator to the positive supply connected to terminal 6, the output is high to 1, on the other hand, trigger terminal 2 is less than 1/3 of the supply voltage. The output goes to 0, if it is more than 1/3. A small change in the voltage of pin 2 is sufficient to change the output state of pin 3 from 1 to 0 and from 0 to 1.
The output has only two high and low states and cannot remain in an intermediate state. It is the power of the 9V battery for mobile use. The circuit is economical in energy consumption. Pins 4, 6 and 8 are connected to the positive supply and pin 1 is connected to ground.
Burglar Alarm Circuit Diagram
Components Required
LED = Light Emitting Diode
LDR = Light Dependent Resistance
IC = Integrated Circuit
Components:-
1) 9V battery with snap
2)LDR
3)Variable resistance 100K ohms
4)Resistance 470 ohms
5)LED
6)IC 555
7)Switch
