Sixpence: You will know what wires are center taps with a ohmmeter. The coils 'end to end' will have double resistance that the coils 'end to center tap', and not same coil ends will show infinite resistance. Just make a table with the colors in each axis on your workbook and try all the combinations. The table itself will be very explanatory when finised.

Ynneb ed alters: Just remember that if you use a unipolar wired as bipolar you need to feed the coils with half the current of the faceplate. It is not obvious but true, and will help a lot in order to make a cheaper driver circuit.

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