School Bell Design

The design of a school bell is based on a daily electronic plug-in timer, a 30 second adjustable delay timer (set at 10 second delay) and an alarm bell operating at 230Vac.

The daily electronic plug-in timer is programmed to activate according to the following schedule:

7.00am ON      7.01am OFF    Breakfast

8.00am ON      8.01am OFF    Class Begins

11.00am ON     11.01am OFF  Class Release

12.00noon ON  12.01pm OFF  Lunch

2.00pm ON      2.01pm OFF    Class Begins

4.00pm ON      4.01pm OFF    Class Ends

6.00pm ON      6.01pm OFF    Dinner

7.00pm ON      7.01pm OFF    Night Class Begins

Everytime when the electronic plug-in timer activates, the 30 second timer will sound the alarm for 10 seconds and then it turns off. Hence the school bell will ring at the pre-programmed time daily.

The wiring diagram of the 30 second timer is shown below:

Finally, the school bell was installed at PKH Training Centre, Aoral powered by 300W solar with inverter.