Fridge Door Alarm Circuit

A fridge door alarm circuit using 555 timers senses the status of a fridge door being open OR close. It beeps if the fridge door is left open for too long or hasn’t been closed properly, in order to stop food from spoiling. There are lots of other implied uses to this circuit as well. A refrigerator or freezer door that is left open or ajar may cause the food contents to spoil. So today in this tutorial, I am going to show how to make a simple fridge door alarm circuit using 555 timer IC

PCBWay 5$ Prototype

Hardware Required

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• 555 Timer IC
• LDR 5mm
• LED 5mm
• Buzzer Small
• Diode 1n4007
• Electrolytic Capacitor47uf
• Ceramic Capacitor 0.1uf
• Resistors 10KὨ – 1; 470KὨ -2; 100KὨ -1; 100Ὠ19
• Breadboard
• Connecting Wires –

Step 2: Solder Base of Both IC’s 555 Timer

Step 3: Place IC in Base

Step 4: Solder All Resistors

Step 5: Solder Capacitors (Ceramic & Electrolytic)

Step 6: Solder Diode & LED

Step 7: Solder LDR & Buzzer

Step 8: Finally Solder Power Connector

Step 9: Let’s Power Up the Circuit

Step 10: Circuit Diagram