8 simple electronic doorbell circuit by 555 timer IC

schematic diagram of electronic doorbell circuit

Simple electronic doorbell circuit (monostable 555  timer IC)

This project  is  a simple electronic doorbell circuit powered by a battery source ranging from 6 volts to 12 volts. This doorbell circuit is powered by a 555 timer IC operated in monostable mode. The use of the timer IC is to set the time delay for the doorbell to ring. The 100K resistor and 33uF capacitor sets the time delay about 3.6 seconds of continuous ringing. Increasing the value of resistor and capacitor increases the time delay about the product of resistor-capacitor combination times 1.1 (1.1RC).
The switch S1 is a push button that will activate the electronic doorbell. The 10K resistor across the S1 and supply voltage provides protection of false triggering of 555 timer.
The buzzer to be used must be self oscillated type or having a built in oscillator for this doorbell circuit to function well.
For  persons with some problem in hearing, you can modify the door bell circuit by replacing the buzzer to LED and 150 ohm resistor (see diagram below), or you can put this LED and resistor in parallel to buzzer for better functionality
The LED is preferably blinker type, but an ordinary one is just okay.

schematic diagram of simple electronic doorbell circuit for deaf

Simple electronic doorbell circuit (astable 555  timer IC)

Another version of simple electronic doorbell is shown bellow. This type of electronic doorbell uses the same 555 timer IC but it is operated in astable operation a generating an audible sound of 2880 Hz. Another difference of this doorbell circuit is the buzzer is replaced by a speaker. The sound frequency is set by the resistors 1K, and 2K, and 100nF capacitor. Increasing their value lowers the pitch of the doorbell sound.

The same with the electronic doorbell above, you can replace the speaker with an LED as an indicator. Advantage of this type of electronic doorbell is you can use a buzzer or speaker while the version above can’t. Disadvantage of this version is it requires more parts and you are going to push the button (S1) all the time for the doorbell to sound.

another version of doorbell