Smoke detectors are generally used
in advanced alarm systems. Most of this professional devices use gas-detectors,
ionization rooms or radioactive elements as sensors. In this LDR & LED Smoke Detector circuits we are not
using any of this complicated components. Instead of LDR & LED Smoke Detector, we are using two
LDRs and one LED. LM1801 special-purpose IC ,which is designed especially for
smoke detectors, provides us building this circuit by using the minimum number
of components. LDR & LED Smoke Detector includes one internal zener supply, two reference voltage
outputs, one voltage comperator, fixing diodes and one 500mA output transistor.
LDR & LED Smoke Detector schematics here:
LDR & LED Smoke Detector schematic figure