It beeps if the fridge door is left open for too long or hasn’t closed properly, to stop food from spoiling. There are lots of other uses as well. A refrigerator or freezer door that is left open or ...
The circuit will provide a beeping sound to alarm the household that the refrigerator door has been opened for more than 20 seconds. 4060 – a 14-bit ripple counter with internal oscillator that has ...