Re: Stepper controllers

Thanks very much Paul, this is helpful. I did try using opto isolators
on one of my early experimental circuits but they just seemed to gum
things up, however, I think now that the problem might have been a
current limitation on the parallel port - I hadn't thought of that. I
have been surprised that I can't drive the steppers reliably with the
486 computer and that stepster and MaxNC both seem to need a pentium as
I too can remember 8080s doing the job admirably in industrial
environments. In fac, only last year I was playing with a giant Asquith
miller (12ft x 8ft bed!) at a military aircraft factory which still uses
an early computer fed by 8" floppy disks.

Ian

paul@... wrote:

>

> In the home shop environment, this is not quite so critical, but to be
> safe, I'd use them. Motherboards are pretty cheap these days, but it's
> still a headache to swap them out.
>
> For a TTL output, or anything capable of sinking the optoisolator drive
> current, you can use something like this for a signal line:
>
> +----\ |
> Sig in | )----|<------\/\/\/\-- +
> +----/ |
> \_
>
> ------
> / \
> \/ \-------+--\/\/\-- +
> | |
> Gnd +--- Sig out
>
> 300 - 500 ohm resistors would work for a 5V supply. You can use a non
> inverting gate as a driver or just use the signal line if there's
> nothing else attached (and it can sink 10 ma). Or you can use an
> inverting gate (7404) and put one on each side to buffer the isolator
> and increase fanout.
>

Best wishes

Ian

--

Ian W. Wright LBHI
Sheffield Branch Chairman of the British Horological Institute.
Bandmaster and Euphonium player of the Hathersage Brass Band. UK.
See our homepage at:- http://www.iw63.freeserve.co.uk or
http://www.iw63.demon.co.uk/ or
http://www.GeoCities.com/Hollywood/6067/index.html

'Music is the filling of regular time intervals with harmonious
oscillations.'