SMOKE DETECTOR Russian patent published in 1999 - IPC

FIELD: electronic engineering. SUBSTANCE: smoke detector has generator 1 connected to radiation source 2 designed for optical coupling with photodetector 4 through radiation dissipated across smoke particles; photodetector 4 output is connected in series with input of shaping amplifier 7 through photocurrent amplifier 5 and high-frequency filter 8; generator output is connected to input of shaper 3 and to R input of flip-flop 10 whose S input is connected to output of shaping amplifier 7 and output, to first input of AND gate 12 output of the latter is connected to R input of counter 8 whose output is connected to input of alarm 9 while C input and second input of AND gate are connected to first output of shaper; second output of the latter is connected to control input of shaping amplifier. Radiation source may be made in the form of group of light-emitting diodes. EFFECT: improved noise immunity in case of occurrence of pulse noise and improved sensitivity to black smoke. 2 cl, 3 dwg