I have a raspberry pi trying to drive an intercom system.
The intercom has a 12V output which when connected to ground opens the door.
What I want to do is have the raspberry pi 3V GPIO switch drive the optocoupler and this will ground the intercom opening the door, like below.
The issue I have is not enough current is passing through the transistor side of the optocoupler to the emitter, with R1 being 150ohm, only 15mA passes through.
The optocoupler I'm using is: http://www.cel.com/pdf/datasheets/ps2501.pdf
I'm assuming I'm using the wrong optocoupler or its something to do with the CTR, but I'm at a loss as to interpret what the issue is.