Hi All,  Bob Essex is correct, you can increase the power supply
voltage of a stepping motor to get more speed.  Let's say you are using
five-volt one-ampere per phase motors.  Increasing the supply voltage
to ten volts will double the speed.  In practice I use a twelve volt
power supply on my five-volt stepping motors.

Here is the secret!  Besides increasing the step rate in the software,
you need to add resistors in series with the phases of the motor.  A
six-wire motor only needs two resistors, while a five-wire motor needs
four.  By increasing the supply voltage while keeping the motor current
the same, a stepping motor will spin faster.  I use eight-ohm
twenty-watt resistors.  It seems magnetic fields like voltage, not
current!

An old computer supply works great!  These power supplies will deliver
five volts at twenty amps and twelve volts at six amps.  Software for
most steppers also allows you to adjust the acceleration rate to
prevent missed steps.  The MIDster has the ability to re-synchronize
itself if the motor loses a step or two.

Bob Essex also mentions using toothed belts (gearbelts).  In CNC and
robotics we use gearbelts to save on cost.  If you use a gearbelt to
drive the MIDster, I suggest you put a motor on each pulley, if your
motors are small.  Wire the motors up color to color.  The gearbelt
forces them to turn together.

CNC machines get speed and accuracy buy using a ball-screw type of
leadscrew.  With only ten turns per inch these leadscrews make the
carriage fly!  They can cost anywhere from twenty dollars surplus to one
hounded and twenty dollars new.  With a two-hundred-step motor and a
ten-turn leadscrew, each step would move the punch .0005 inch.  With
this type of leadscrew you get both speed and accuracy.  I use threaded
screw rod, 1/4-inch 20 tpi, in my CNC machines because it is cheap and
easy to find.  I don't know if the MIDster will work as is with this
type of leadscrew.

John Conrad Kleinbauer

 [ That's a useful circuit you describe, John.  The old-timers called
 [ it a "long-tail" power source, and it enables the current in the
 [ motor windings to build up faster.  The series resistor also
 [ helps to limit the steady-state current to a safe value, to prevent
 [ overheating.   -- Robbie