I am working on a robot when I have a little spare time (who isn't ;-D)  My
first attempt involved using motors from old 5.25" floppy drives.  They are
cheap and easy to work with, but have virtually no power.  They are 4-phase
motors, making it easy to drive them.  I now need more power, and I found
some cheap(US$7.00) surplus Vexta NMEA-17 2-phase motors.  These motors are
rated at 6V .8A.

My old driver board uses TIP-120's driven thru a buffer IC with extra bypass
diodes added.  These had no trouble with the floppy motors even without heat
sinks.

Now for the questions:

1  Since these are 2-phase, do I absolutely have to flip polarity's on the
winding coils to get the motors to run?  These motors have 6 wires, so it
seems that they are center tapped.  Maybe I can just tie the center taps
together, and drive the motors the way I did the 4-phase motors????

2  Am I going to have to build a new driver board to accommodate the 2-phase
motors.  If so, should I just find some type of stepper control IC?

3  Do you all think that TIP-120's are stout enough to drive these motors?
5 watts doesn't seem like too much of a load on a tip-120, is that correct?
I guess I would need to add some heat sinks, though.

Michael Brown
Instant Net Solutions
www.KillerPCs.net

"In the land of the blind, he who has one eye is king"

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