Monday, December 23, 2013
THIEF ALARM
BURGLAR ALARM
To detect the present robber we have used LDR and a source of light.
LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has a resistance of about 1 megaohms when in total darkness,but a resistance of only about 2-5 k ohms when brightly illuminated. It responds to a large part of the light spectrum.
LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has a resistance of about 1 megaohms when in total darkness,but a resistance of only about 2-5 k ohms when brightly illuminated. It responds to a large part of the light spectrum.
The source of light and LDR is so adjusted with a reflector that light will directly fall on the LDR but when robber enters inside then it will block the beam of light and LDR will be under darkness.
1)9V battery with snap
2) LDR
3) Variable resistance 100K ohms
4) Resistance 470 ohms
5) LED
6) IC 555
7) Switch
2) LDR
3) Variable resistance 100K ohms
4) Resistance 470 ohms
5) LED
6) IC 555
7) Switch
8) BUZZER
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