The application circuit of the photocoupler

Published:2011/5/21 4:30:00 Author:Borg | Keyword: application circuit, photocoupler | From:SeekIC

1.combination switch circuitIn the circuit of figure 1, when the input signal(ui) is a low LEV and the diode(V1) is stopped, the current of the LED in photocoupler BI is close to 0, the resistance between output terminals Q11 and Q12 is very high, which is equal to off ; the ui is a high LEV, vi is passable, the LED in BI is glowing, the resistance between Q11 and Q12 turns down, which is equal to on . As when ui is always a low LEV, the switch is off, so that it's often in high LEV state.



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