Thank you for your fast reply.
DVDdoug:
Please show us a schematic. I' not going to try and draw one or visualize the circuit from your description.
I drew a Schematic, hopfully it gets more clear with that.
DVDdoug:
I'd be surprised if that thing can power a fan. I looked at the SparkFun website and I didn't see a current spec and I didn't see what transistors they are using.
If I read the Datasheet corretly (I'm not so sure :/) it can handle a voltage up to 70V (the Collector emitter breakdown voltage, or for what voltage would I need to look?)
I'll try the tip with the led, but that will take a while cause I will need to solder a little bit.
Edit: Regarding my guess: I meant, if I switch the ground (with a physical switch, the optoisolator not in my circuit) they still run
Edit2: I found out something rather interesting while testing out with the LED, if I disconnect my fan I get the correct 12V.
The LED lights correspondingly also correct.
What could be the reason that as soon as I connect my fan to the circuit (12V) it doesnt output the correct Voltage? Could it maybe be related with the common ground? If so how can I connect them in another manner?
