Hello KlausST,
The sensor has protection built-in, the sensor communicates with the car ECU.
I just want to come in parallel with a measuring equipment.
The sensor`s output is dependent on the pull-up in the ECU that is connected to the battery. So when the battery voltage changes, the signal changes itself.
I would like my equipment not to interfere with the current communication, just to monitor it, that is why I want only to protect the side on my micro-controller`s input.
I do not care to protect the sensor in my case, that is protected by the manufacturer.
My idea was to use the optocoupler to be somehow independent on the voltage changes (11V-16V) because my 3V micro-controller has a regulated voltage.
Is this OK just using the BJT ? Then i will do it like that.