-----Original Message starts -----
Michael Shiloh wrote ** edited **
 I could be wrong, but didn't the original poster say he his motor had 5 leads?
This would suggest an internal star connection, with
1 common lead and 4 leads for the other ends of each coil. If I understand this
correctly, this would make it impossible to use in a
bipolar mode.
-----Original Message ends -----

Hi
  Actually It works just fine. The 5 wire motor is a modified 6 wire motor. When
 driving the 6 wire motor in the bipolar mode the
center taps are left unconnected and float at 1/2 of the applied voltage. It doe
sn't matter which way current is flowing in the
coil, the voltage is always the same for both coils. In addition the inductance
and capacitance associated with each coil is the
same so the relationship holds for complex ac waveforms as well.

 The 6 wire motor.
      coil#1A       coil#1B
      =====================
(gnd)---\/\/\/\---.---/\/\/\/----(+6v)
                  |
                  +--------------(+3v) <---.
                                           |**
                  +--------------(+3v) <---'
                  |
(+6v)---/\/\/\/---'---\/\/\/\----(gnd)
      =====================
      coil#2A       coil#2B

** this connection made to turn 6 wire motor into a 5 wire motor

  The 5 wire motor has the Center taps tied together, but connecting two equal p
otentials together has no effect on current flow. I
have done this many times and it has always worked. I suppose there are minor di
fferences in the coils and they do reduce efficiency
somewhat, but compared with the increase of torque they are not noticeable.

  I have not tried this with a chopper driver yet, but I think it may not work.
The small differences in coil impedance might cause
one coil to charge faster and turn off before the other does. In that event the
voltages would not be equal and strange things could
happen.

  The big problem is the 5 wire motor can not be connected correctly with only t
he information from an ohm-meter check because the
resistance from wire 1 to wire 2, 3, or 4, is the same. In fact the only wire yo
u can identify correctly is wire 5. the rest must be
found from the spec sheet or from trial and error.

 A previous post, I forget by whom, to this list suggested using a speaker to fi
nd the correct wires.
  connect + 1.5 volts and one speaker lead to the center lead
  choose a wire at random and connect the other speaker lead
  momentarily connect the remaining leads to ground one at a time
  the lead with the loudest click matches the lead the speaker is connected to.
  the remaining two wires are the other coil

- This sounded like a good idea to me but I haven't tried it yet.
. . Brian

  Do not take the motor apart to trace the wires. The rotor of a stepper motor h
as many poles that must align exactly ( like within
a few 1000ths of an inch ) to the --gear-- teeth of the stators. To achieve this
 accuracy the rotor is magnetized after the motor is
assembled. Taking it apart and putting it back together again usually destroys t
he alignment and the motor never works again. It may
turn but it will not produce the torque it was designed to.
--------------------------------------------
Brian Whittaker SVSKITS.COM
Voice: 510-582-6602 FAX: 510-291-2218
SVS_KITS@MSN.COM URL: http://www.svskits.com