Jon Petty wrote:
> I just started to get my circuit ready for my first stepper motor project. It
> is a small 6 wire stepper. I have two styles of steppers the colors are
> (blue,brn,red,wt,brn,orange) and the other (yellow,brn,blk,red,brn,orange). I
> bought them surplus from All Electronics.
>
> How do I determine which wires are common power and which wires go to coil
> 1,2,3,4 respectively?

Jon, six wires means the two coils are apart, 3 wires per coil.

If you have an Ohmmeter, just measure the resistance between any 2
wires, when you find an open circuit, it means both wires are not from
the same coil, then isolate one.  When you isolate the single coil 3
wires, you will have 3 measurements between them, the highest resistance
means the not used wire is the center tap, and goes to +Power or Ground
(according to your unipolar drivers), while the other two wires goes to
the drivers. The same for the other coil.

If you don't have an Ohmmeter, connect a small lamp (Christmas tree lamp
is ok) to any two wires of the stepper and rotate the motor shaft by
hand vigorously, the two wires that makes the lamp lit brightness are
the extremes of the coil, while the low brightness identify the center
tap.  The same experience is just shorting circuit any two wires
together, heavy load when rotating the motor shaft identifies the
extremes of the any coil, while light load means the center tap
connected to any extreme. This effect is because the stepper acts as an
generator when its shaft is externally rotated.

If you are planning to use bipolar connection, just forget the center
wire and use only the two that shows the highest resistance, connecting
them to the bridge.

Wagner.