Simple Electronic Door Buzzer

Here is electronic project of Simple Electronic Door Buzzer has a very simple function and is very easy to build.  This door buzzer circuit use a LF351 operational amplifier and other few common electronic components.  When the S1 push-button is depressed an initial positive voltage is placed on the C2 and the non-inverting terminal of the LF351 operational amplifier and the circuit will oscillate at a low frequency.

Simple Electronic Door Buzzer Circuit Diagram:

The used speaker for this project must have a impedance between 40 -80 ohms.  The door buzzer electronic circuit needs to be powered using a 9 volts DC power supply.