Door Bell Circuit

In this tutorial, we are going to design a Simple Doorbell circuit using a 555 Timer IC. It is a very common and useful device. Almost everyone uses it. The main feature of this doorbell circuit is that we can control its time duration. So it keeps on ringing as the switch or button is pressed.

The 555 Timer IC controls the oscillation frequency of the doorbell sound. Every doorbell produces different types of sound depending n their functionality.

Hardware Components

The necessary hardware items required for Doorbell Circuit:

Sl. Component Quantity 

1. Breadboard.              1

2. 9v Battery.                  1

3. Connecting Wires.   1

4. 555 Timer IC.             2

5. Variable Resistor  (10k ohm)×1

6. Resistors (1k,10k,100k ohm)  1,2,1

7. Capacitor (1000uF,1uF)           1,1

8. Buzze .                          1

9. Push Button.              1

Working Explanation

The Doorbell circuit consists of two 555 Timer ICs. One IC controls the ring duration and the other IC controls the oscillation frequency of the sound produced by the bell. The first-timer IC operates in monostable mode. And the second timer IC operates in as table mode. In this way, the first-timer IC modulates the frequency of the second timer IC. In order to control the ring duration, an output of the first-timer IC is connected to the reset pin of the second timer IC. This means that as long as the output of first-timer IC is high the second IC oscillates. There is a difference between the as table mode and the monostable mode. An as table mode is free running and it does not require any external triggering. This has no stable state. Whereas monostable requires triggering for high and low.

Application

• This circuit has many applications in houses, restaurants for serving, in hospitals and several other places.

Doorbell Circuit Diagram