differential amplifier with light intensity change measurement circuit

Published:2011/5/23 22:46:00 Author:John | Keyword: light intensity change measurement | From:SeekIC

Figure (a) is a sensitive optical differential amplifier circuit. It has two identical photosensitive transistors (such as BPY62), being respectively connected to the op-amp 709 through its symmetry emitter follower BC107. Resistors R1 and R2 are determined according to the ambient brightness. Potentiometer RP2 can be used to adjust symmetry of two-input divider and operational amplifier. Potentiometer RP1 is used to adjust the amplification factor. The phototransistor base in this circuit opens. Figure (b) circuit has a good advantage of adapting to ambient light conditions.



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