Bridge luminometer circuit

Published:2011/5/13 2:29:00 Author:Nicole | Keyword: luminometer | From:SeekIC

The electric bridge is composed of phototube PC1, R1, R2, R3, differential input terminal of operational amplifier 741 is connected to the middle point of electric bridge both arms. When PC1 has no light, the electric bridge is balance, 741 output is 0, after it has light, the electric bridge loss balance, 741 output terminal level is directly proportional to the brightness, the meter indicates the brightness value. The balance adjustment steps of electric bridge: you can shading the phototube at first, adjusting R5 to the maximum value, then adjusting R3 to make the meter indicates 0. To reduce R5, making the meter hand stray away from 0, then adjusting R3 to make the meter indicates 0. To repeat this process, it can obtain the maximum sensitivity. The broken line shows 0.1μF decoupling capacitance.



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