[pminmo]

Originally Posted by AlainB Hi, Thanks! My question was only about the benefit of the 74HC14N. To be more specific, what does it do, i mean when used for instance in a (unipolar) stepper motor driver. I can imagine that one usage of this chip it is to "condition" the output of the parallel port but what is wrong with the output of a parallel port? Wy does it need to be conditionned. Sorry! The computer power supply I was talking about is an external power, not the computer's power supply. Many thanks!! Alain

The problem isn't specifically with the parallel port, but the cabling from a parallel port to something. Using a 74HC14 helps clean up the signal transitions that can be influenced by the cable.