Automatic School Bell Circuit PCB

Posted on Feb 7, 2014

Consider that a school has a total of eight periods with a lunch break after the fourth period. Each period is 45 minutes long, while the duration of the lunch break is 30 minutes. The bell will be ringed to start the class, end of each period, extension at lunch break etc. To ring the bell to start first period, the peon needs to momentarily pres

Automatic School Bell Circuit PCB
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s switch S1. The 555 timer IC is configured as an astable multivibrator whose clock output pulses are fed to the CD 4017 IC. IC2 increases the time periods of IC1 (4. 5 and 3 minutes) by ten times to provide a clock pulse to IC3 every 45 minutes or after 30 minutes, respectively. When the class periods are going on, the outputs of IC3 switch on transistors T1 and T2 via diodes D4 through D12.

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