sensor for Firefighting robot
I need to use sensor which can detect candle's light in average lighted room (it's not allowed to use micro-controllers)
Not possible or trivial if average light includes tungsten lamps.
One would need an Infrared scanner with a roatating mirror using a linear array og high gain narrow angle detectors or a camera CCD array. Dyalight blocking filters are essential.
In any case some vision system is needed,
I would have though that a flickering flame would produce an LF audio component on the output of a photodiode.
Frank
Yes Frank, perhaps after 80dB notch filters at 120,60 Hz or 100,50Hz from fluorescent, and tungsten light and very high gain, while motionless.
LDR will also be a good choice and can be used with opamp for light sensitivity.
Flame detectors utilize UV sensors which are independent on ambient light. Some scanner will be needed for your application
Instead of using notch filters to get rid of 50 HZ pick up, why not use a 50 HZ synchronous detector. The 50 HZ would be a steady DC component, while the flickering would not be.
Frank