Home Security Systems

This circuit so called housing security and safety systems. where when key from this circuit applies LDR, principal from LDR was if there are light entering LDR hence its the low resistance,sehingga current would will pass, but otherwise there are light hence its the height resistance would, so that current will be overcome to IC1, and will be strengthened again by Q1 which then can turn on buzzer.

Parts:
R1 10K 1/4W Resistor
R2 LDR / photo resistor (any type)
R3,R4 100K 1/4W Resistors
C1 10nF 63V Polyester Capacitor
C2 100µF 25V Electrolytic Capacitor
D1,D2 1N4148 75V 150mA Diodes
IC1 4060 14 stage ripple counter and oscillator IC
Q1 BC337 45V 800mA NPN Transistor
BZ1 Piezo sounder (incorporating 3KHz oscillator)
SW1 Miniature SPST slide Switch
B1 3V Battery (2 AA 1.5V Cells in series)