Smoke Detector

1

Smoke Detector
∗ Sardar

Nimisha Sankhe∗ , Nisarg Vinod† and Ekta Vira Patel Institute of Technology, Mumbai-400058, India, [e-mail] † Sardar Patel Institute of Technology, Mumbai-400058, India, [e-mail] ‡ Sardar Patel Institute of Technology, Mumbai-400058, India, ekta [e-mail]

Abstract Most of the smoke alarms available in the market use one or another kind of smoke sensor which increases the cost and also require complicated interfacing circuitry around it. But this smoke alarm circuit uses readily available photon-coupled interrupter module as smoke detector. The functioning of this smoke alarm is to continuously detect smoke and automatically activate the alarm in case of dense smoke. Loud sound is heard continuously indicating the presence of smoke till smoke clears. After this, the circuit is automatically reset for further detection of smoke provided it is kept in power ON condition.

I. I NTRODUCTION A smoke detector is a device that contains a physical mechanism or electronic sensor that quantifies smoke that can be integrated with or connected to other devices that detect the presence of smoke within an enclosed space. 1) Theory : Smoke detection technology was developed from a very primitive times by use of chemicals but the electronic way of its implementation had a profound effect on efficiency in detecting smoke. The basic idea is to detect the change in air density due to smoke and give out an alarm. The first home smoke detectors were invented by Duane D. Pearsall in 1967. 2) Methods of Implementation : a) Chemical Detectors : Most of the times, smoke is caused by fire or ignition. Hence by detecting gases in particular environment we can predict about presence of smoke. These detectors use Carbon Monoxide (CO) or Carbon Dioxide (CO2 ) sensors which sense level of these gases in atmosphere and activate alarm accordingly. But these detectors are not accurate enough to be implemented. b) Ionisation