Door bell circuit using NE555


Posted on Feb 6, 2014

The main part of this doorbell circuit are two NE555 timer ICs. When some one presses switch S1 momentarily, the loud speaker sounds a bell tone as long as the time period of the monostable multivibrator built around IC1. When the switch S1 pressed, IC1 is triggered at its pin 2 and output pin 3 goes high for a time period previously set by the val


Door bell circuit using NE555
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ues of POT R4 and POT R5. When the output ofIC1 goes high it resets IC2 and it starts to oscillate to make a bell sound through the speaker. The IC2 is configured as an astable multivibrator whose oscillation frequency can be varied with the help of POT R5. By adjusting the values of R4 & R5, modifications on the tone are possible. If you are not familiar with the basics of 555 timer IC, and its applications, you can buy books that will help you get a better understanding from our online store. Totally 3 books have been reviewd in detail along with their authors. You can get their reviews and buy them here:- 3 Great Books to Learn 555 Timer Circuits and Projects




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