Log photometer circuit

Published:2011/4/13 20:53:00 Author:Nicole | Keyword: log photometer | From:SeekIC

This circuit can be used to test light intensity of air conditioning equipments. The light intensity is changed into voltage(the maximum voltage is 400mV when it is 100000). Photosensor adopts silion photodiode BPX91. This diode is in no load operation, and it will produce output voltage, the voltage has a logarithm relation with light intensity. Transistor BCY58/X amplifys photo-sensitive current, collector-emitter diode can compensate the temperature factor of photodiode. TAA761 and Potentiometer Rp2 makes the light intensity have a function relation with output voltage. The main technical parameters: working voltage: ±15V; consumption current: about 15mA; output voltage(E=100000lx): 0~600mV; the minumim light intensity withtout filter(adopts incandescent lamp): ≈1.5lx; the minumim light intensity with filter: ≈15lx.



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