This project has been triggered by the challenges being experienced by fridge operators, where sometimes they might think that they have closed the fridge door only to realize when it is too late that they left the door open.

The Simple Alarm for Fridge door is a printed circuit board project which is built on the idea of informing the user of the fridge on the status of the door that is if the door of the fridge is closed or open. The system has an inbuild beeping alarm made from a buzzer which beeps anytime the fridge door is left for a long time without being closed. It finds use in areas of temperature-controlled freezers, refrigeration, and soft drink coolers.


KiCAD Software


1.       555 timers; IC type (2)
2.       5 mm LED,
13.       5mm LDR 5 mm;
14.       1N4007 Diode;
15.       Buzzer(small);
16.       0.1 uF Ceramic Capacitor;
17.       47uF Electrolytic Capacitor;
18.       Breadboard;
19.       Connecting Wire(Enough) 10.   Resistors; 10K; 1 470K;2100K;1100n;1

How schematic Works:

The operation depends on the communication between the two NE555 timers, which do so simultaneously. We shall have U1 doing the evaluation then correspond with the LDR input then U2         will utilize the signals it receives from U1 to control the Buzzer based on the fridge door position.