SMOKE
DETEKTOR CIRCUIT USING LDR
This
is a simple Smoke Detector circuit based on a LDR and lamp pair for sensing the
fire. It uses a very simple approach to detecting smoke in the air. The alarm
works by sensing the smoke produced during fire. The circuit produces an
audible alarm when the fire breaks out with smoke.
Smoke
Detector circuit using LDR
When
there is no smoke the light from the bulb will be directly falling on the
LDR.The LDR resistance will be low and so the voltage across it (below .6V).The
transistor will be OFF and nothing happens. When there is sufficient smoke to
mask the light from falling on LDR, the LDR resistance increases and so do the
voltage across it.Now the transistor will switch to ON.This gives power to the
IC1 and it outputs 5V.This powers the tone generator IC2 to play a music.This
music will be amplified by IC3 to drive the speaker.
The diode D1 and D2 in combination drops 1.4 V to give the rated voltage (3.5V ) to UM66 .UM 66 cannot withstand more than 4V.
Tidak ada komentar:
Posting Komentar