i have a 0.7V source that is coming out of another circuit (car controller) that needs to be sinked. If wire is simply connected to ground the doors will lock. If the wire is connected to a 470 Ohm resistor the doors will unlock.
I have tried an optocoupler but it appears that even under saturation conditions the doors will only UNLOCK.
Well the other end is coming from the car controller. Maybe I didn't express my problem well enough but your solution seems to always leave the cable to ground with the 470ohm resistor in between which is not what I want. Lets try again. I have a wire in my hand coming from that car controller at 0.7V to ground. When u ground that wire doors open. When I put a 470ohm r in inline then ground the doors lock. When I have the wire in my hand nothing happens (duh)
Having that connected all the time would send constant signal to the cars computer to lock the doors.... Which it will gladly repeat over and over again.. The cable needs to be not connected to anything for no action.... There are three discrete states here. Not two
There are three discrete states here. Not two