Stepper motor 101 was Re: Lini-stepper

I'm assuming the output transistors operate as current sinks. This
means they are operating in the linear region (simultaneous voltage
across and current thru the transistor).

For linear operation it makes no difference if bipolar NPN or n-
channel MOSFET transistors are used. The power dissipation in the
device will be exactly the same. 1A of current with 30V across the
device is 30 Watts either way.

Mariss



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@...> wrote:

>
>
> > And the PIC makes an interesting and flexible way to drive it.
> >
> > But OK, not linear, but an approximation of a sine wave, similar

to

> micro
> > stepping.
> >
> > Alan KM6VV
> >
>
> > > IME Linisteppers work fine in their "designed-for"

applications...

> > > IMO they're great for learning about--and messing with--
> > > PIC "stepper" code, and while the heatsink and power supply
> > > requirements are bigger than for chopper drives; they are still
> > > inexpensive and user repair-able.
> > >
> > > ALSO, the Lini- is NOT linear stepping; but linear

amperage/winding

> >
>
> This is where the polishing of the program and circuit needs to be
> done.
>
> Switch to FET's to lower heat. a no brainer.
>
> Linear amperage does not equal linear steps, but then there has

always

> been the discussion of exactly where the step/armature is on a
> microstep. is it exactly at 1/7th of a full step, or is the power
> ramping between steps smoother that offers better power delivery ?
> and it is 'somewhere' between 1/2 steps, but not exactly linear ?
>
> Also, there is that how close is good enough bit. does a screw

with

> 26,000 steps per inch suffer if the step if off by 1/10th of a

step ?

>
> Dave
>