I am updating some controls on an older machine and have found that they are using Sharp PC829 photocouplers for stepper card control.
I noticed that they are using both 5VDC and 24VDC to "actuate" the photocoupler. The data sheet for the photocoupler shows a maximum input voltage of 3V.
I see that the collector/emitter can handle up to 35V, but how are they getting away with the higher voltage on the input side? I see no resistors in the drawings.
I confess my experience with photocouplers is minimal, and any insight would be welcome.
I noticed that they are using both 5VDC and 24VDC to "actuate" the photocoupler. The data sheet for the photocoupler shows a maximum input voltage of 3V.
I see that the collector/emitter can handle up to 35V, but how are they getting away with the higher voltage on the input side? I see no resistors in the drawings.
I confess my experience with photocouplers is minimal, and any insight would be welcome.