SMOKE-SENSITIVE ALARM Russian patent published in 2007 - IPC G08B17/10 

FIELD: fire-fighting, particularly fire alarms used to determine air absorbance increase from infrared light dissipation intensity.

SUBSTANCE: smoke-sensitive alarm comprises processing and control unit, smoke detecting signal conditioner, optical indicator, unidirectional conduction member, two input clamps to connect the alarm to signaling means loop, current switch, current and voltage limiting element, two condensers, radiator, photodetector, optical chamber with light-absorbing walls and voltage divider, which shares voltage between processing and control unit output and current switch input. Current switch includes bipolar transistors connected in accordance with Darlington's scheme. Output voltage divider ratio is set to provide module of ratio between summary thermal instability of base-emitter voltage of current switch transistors and voltage drop of emitter resistance of current switch equal to temperature coefficient of radiator power at thermostable pulse amplitude at processing and control unit output.

EFFECT: possibility to compensate radiator power reduction.

1 dwg