Does anyone know what the minimum current that the PR33-20 opto-isolator’s require in order to register a high?
For context, here is my application (feedback welcome).
I have a 24VDC sensor that toggles an output on and off connected to a float switch. The other side of the float switch is a solenoid valve that requires 29ma to open. I would like to use the PR33-20 to monitor the state of the output and the state of the float switch.
The challenge is to be able to determine the state of the float switch while the output is off. My plan is to use 1 input of the PR33-20 to monitor the output directly. Then feed the 24VDC output through a diode, and have a pull up to 24VDC. Another input on the PR33-20 past the float switch would be used to monitor the state of the float switch. The challenge is to make sure the pull up is sized to provide enough current to trigger a high on the PR33-20 past the float switch, but not enough to risk activating the solenoid.
I tried to figure out what opto-isolators the board uses from the pictures online, but it is a bit hard to tell for sure.
Dennis