13-06-2012, 01:19 PM
PROJECT ON EARTHQUAKE ALARM
EARTHQUAKE ALARM.doc (Size: 118 KB / Downloads: 98)
INTRODUCTION
Earthquake, vibrations produced in the Earth’s crust when rocks in which elastic strain has been building up suddenly rupture, and then rebound. The vibrations can range from barely noticeable to catastrophically destructive. Earthquakes can release energy thousands of times greater than the world’s first atomic bomb.
CIRCUIT DESCRIPTION
The circuit comprises a 555 IC which is used as multivibrator and an audio oscillator where transistor oscillate due to (+)ve feedback through C-3. When the earthquake sensor activates, it trigger pin-2 of IC through negative potential and its output become positive and the connected oscillator gives alarm indication. For that moment a negative pulse is applied to the trigger pin and IC performs for 10 seconds (monostable operation). As the output of IC gets applied to the audio oscillator you will hear alarm for this period. The time of oscillator may increase by increasing the value of C-1.