Stepper motor 101 was Re: Lini-stepper

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Steve Stallings"
<stevesng@...> wrote:

>
> Well not exactly a no brainer.... the LiniStepper
> is called a "linear" driver because its output
> stages operate in the linear region NOT as switches.
> Changing to MOSFETs without redesigning for use
> as chopping switches will not change the power
> dissipation in the output stage.
>
> Regards,
> Steve Stallings
> www.PMDX.com
>

Correct. Driving the circuit in the linear range is where the heat
comes in.

IIRC from my reading and re-reading the notes on the unit, Roman said
it was for a project, he made the circuit, moved on and left the stuff
in the public domain.

Again, from memory, he said that the circuit was not fully fleshed out
and that although it worked for his needs, there was some room for
improvement.

Just adding a comparitor between the base/gate and the signal, and
some support parts, one could change the unit into a PWM circuit and
get away from driving the transistors in the linear range.

But, maybe that would be a SatuStepper or PWMStepper ? running the
chips saturated would drive the effective resistance way down as well
as the heat.

But, it should be mentioned that solving the heat problem does not
solve any control issues. mid-band resonance or any such other problems.


Dave