Does any one know the amperage of a parallel port on an average PC? I am trying to figure out the resistance required to make it equal 0V. so i can avoid constantly triggering my Transistor. Any Help is appretiated. Thanx.
Not sure that I really understand your request, but the PC reference manual indicates that a parallel port pin should be capable of sourcing 2.6mA and sinking 24mA. Perhaps if you include a simple drawing we can be of more assistance.
The current your parallel port will sink or source will eb dependent on the amount of load you have. I=V/R not V=I/R. Current is a FUNCTION of voltage. If the parallel port is trigerring your transistors even it is in its low state, probably you're transistor is not biased properly and check if your PC and circuit has the reference point or ground level.