Probably since the time schools came into existence school bells were used in the system, an indispensable piece of equipment for every school.
They are basically a mechanical device that is able to produce a loud and sharp sound under the influence of an external applied force. Specifically, old fashioned school bells had the form of a large gong (circular brass disc). A wooden mallet (hammer) was used to hit or bang the gong, and produced a sharp ear piercing sound, audible from quite a far distance.
The function of a school bell has fundamentally remained the same since the beginning – to divide the class periods into equal parts and indicate their start and finish with a distinctive sound.
This type of bell has slowly been replaced by more efficient electric bells and they are in use even today in most schools for the same purpose.
But one particular drawback of school bells is that these need to be operated manually and thus someone always needs to remain alert and activate the device on time.
The job can be strenuous physically as well as mentally, and still, strangely, you will find many schools are not equipped with an automatic device that can do the job all by itself.
The present article deals with a simple electronic school bell timer designed for the specific purpose of ringing the bell on time. When built it is able to switch ON and OFF an electric bell automatically, at regular time intervals, depending on its settings.
Before we learn the construction details, let’s first make sure we know how an electric bell operates to make a school bell sound.