Monday, February 13, 2012

Refrigerator Alarm schematic

Refrigerator Alarm circuit, so that we know whether the fridge is closed or not. Refrigerator sometimes likes to play or open the lid by the children, and this resulted in a refrigerator at room temperature decreases and will increase the electrical load, so that the electricity to be extravagant. Therefore it is necessary alarm circuit.

Alarm circuit schematic drawings Refrigerator

Circuit placement and How it Works: This circuit is stored into a small box, placed in the fridge near the lamp (if any) or the opening. With the door closed in the refrigerator in the dark, the photo resistor R2 presents a high resistance (> 200K) thus clamping IC1 by holding pin 12 high. When a beam of light came when opening, or a refrigerator light bulbs, photo resistor lowers resistance (<2K), pin 12 so low, IC1 starts counting after a predetermined delay (20 seconds) piezo sounder beeps sound for 20 seconds. then stopped during the same time interval and the cycle repeats until the fridge door closed. D2 is connected to pin 6 of IC1 allows the piezo sounder beeps sound 3 times per second.

List of Components:

R1 10K 1/4W Resistor
R2 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)

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