Stepper motors
        <snip>
> Test out each individual part separately without the micro.... i.e. use
> twisted wires and your relays/transistors to drive the motor by hand then
> hook to your micro.  Make sure you start the pulse counting slow, because
> if you go too fast you will saturate the relays as they have a max switch
> rate.
>
> -Erik Reikes
>
        Relays ???,  Common 0 volts ???
        Get with the modern approach - opto isolation between 2 *COMPLETELY*
separate circuits.

        Many advantages are gained, not least freedom from inductive
interference and ground loops, and you can physically separate the circuits
by at least 5m of ribbon cable. If you build the opto couplers by hand, ie.
use discrete LEDs and photodiodes, you can separate them by 20m of cheap
optical fibre (clear, thick fishing line).

        Hint - if you fit a reverse biased diode across the opto coupler LED
and a large value (1M) pull down onto the base of the phototransistor in the
opto coupler you will be able to achieve *CLEAN* switching up to the maximum
rate the stepper motor can handle.

        Bye.