Smoking Warning Indicator (1)

Published:2011/5/19 2:50:00 Author:Sue | Keyword: Smoking, Warning, Indicator | From:SeekIC

When gas sensor detects no smoke, the resistance value between A and B will be very large, and B's voltage will be low. Then V1 is disconnected, so the loudspeaker doesn't work. When gas sensor detects smoke, the resistance value between A and B will become small, making B's voltage higher, so V1 is connected. Its emitter will output high level, making IC2 begin to work, so loudspeaker BL will make a warning sound of No Smoking! When there is no smoke, the resistance value between A and B becomes large again,so V1 will stop working because of the low voltage of 1.4V.Then the warning sound stops.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Audio_Circuit/Smoking_Warning_Indicator_1.html

Print this Page | Comments | Reading(3)