At 14:07 06/04/08, you wrote:
>A general stepper question - Should steppers be driven with a short
>pulse then allowed to free-wheel.
A stepper motor has positive indexing, it doesn't 'free-wheel'
in normal use. That's why it's called a stepper motor. ;-)
It has a higher holding torque whilst energized: if you
need high holding torque then power it continuously.
If you don't need much holding torque, it's up to you how
long the drive pulse is, as long as it contains enough
energy to step the motor and it doesn't exceed the
voltage/current/power ratings of the windings.
Note that the windings are highly inductive so a high
voltage is necessary for high stepping rates but static
high voltage drive will lead to large ohmic losses.
So consider what happens if there is a software error ;-)
> It seems that this might make the
>motor turn more smoothly.
Not even wrong, as Don Lancaster might say.
When you pulse it, the motor will step: that's
what it is designed to do. If one step is too
coarse for you, learn about micro-stepping.
>How would I work out how long the pulse
>should be?
Options:
(a) calculate from the parameters of your motor
(b) reverse-engineer your LJ-5L (or measure a working one)
(c) suck-it-and-see (probably easiest in the circumstances).
Basically, with insufficient drive the motor won't step
reliably, especially under load, but too much won't make
much difference until you hit the max ratings. So find out
what works and add a safety margin.
There's _lots_ of stepping motor info on the Web - go Google.
Regards, LenW
--
Quote little, say much - as a general guide,
your reply should be bigger than your quote
(and following it, of course,)