Hrm, reading this page says: Transistor Circuits
The collector-emitter resistance RCE is controlled by the base current IB:
Which makes sense I guess.
I have a 1k resister between the parallel SIG pin and the BASE pin of the transistor. Perhaps this needs to be reduced to make this work on a low voltage parallel port? I only have 330 ohm resistors at my disposal... will this burn anything out if I was to use it again with the arduino later?