Friday, 15 January 2016

House Safety Alarm

Now you can catch the burglar:-
We can use single NAND gate to make burglar alarm. This can be done by using NAND gate (combination of NOT and AND gate ),an LDR (light depending resistor), a push button Switch S and an alarm on picture attached.
Cinnect LDR between NAND gate input B and rhe positive terminal of the battery.
The LDR will cause a High level input '1' at B when in light because of its Low resistance. The LDR will cause a low level input '0' at B when light is interrupted and cause high resistance in LDR .
A low level signal is also caused at A when burglar steps on switch S.
si this burglar alarm sound when either burglar interrupts light falling on LDR or steps on switch  S.

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