ELECTRONIC DOOR BELL ECE Paper Presentation And PPT

At the heart of this doorbell circuit are two NE555 ICs(IC1 and IC2).When any body presses switch S1 momentarily,the loudspeaker sounds a belltone as longas the time period of the monostable multivibrator built around IC1. The circuit is powered by a 9v battery.when switch S1 is pressed,IC1 is triggered at its pin 2 and output pin 3 goes high for a time period set using preset vr1 and CAPACITOR c1.The high output of IC1 resets IC2 and it starts oscillating to produce a belltone through the loudspeaker.IC2 is wide as an Astable Multivibrator whose Oscillation frequency can be varied with the help of preset VR2,so various tones can be heard through loudspeaker LS1. The circuit can be housed inside a plastic box and mounted on the rear side of the door.If the door is wooden,solder or wire to switch point of the circuitand mount an aluminium plate in front of the door.