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A refrigerator door alarm circuit diagram

2016-02-18 15:32  
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This article is an introduction to the door alarm circuit diagram . Do you have any idea on the circuit and opinions, welcome to contact us. At the same time also hope that this article is helpful to you. This circuit, enclosed in a small box, in the fridge near the lamp (if any) or open. In the interior of the closed the fridge is in the darkness, the photo resistance R2 with high resistance (> 200 k) and clamping IC1 portable pin 12 is high. When a beam of light to enter from the open, or the fridge lamp lights, this photo resistance to reduce the resistance (< 2 k), pin 12 is low, IC1 began to count, after a preset delay (20 seconds in this case) piezoelectric ring beeps, lasts 20 seconds and stop to the same period of time and the cycle is repeated until the door closed. D2 connecting pin 6 IC1 make piezo sounder beep three times per second. In this circuit, connected to pin 2 D1 IC1 delay time in half. Delay time can be various changes of C1 and/or R3 value. Any photo resistor type should work well. 



Fridge alarm circuit diagram

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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