Help Choosing B.O.B. and Drivers

[Jesse B]

I've decided to go with the DIY route for my Breakout Board and Drivers. I've narrowed it down to 2 drivers which I can't seem to choose between, and a bunch of Breakout Boards which I really don't know the difference. So a little help would be appreciated

Driver #1: THS Engineering A3977 Stepper Motor Driver
http://www.thsengineering.com/projec...3977proto.html

Driver #2: Linistepper V.2
http://www.piclist.com/tecHREF/io/st...step/index.htm


Both of these drivers do micro-stepping, and both put out enough voltage/amperage to drive the motors I'm looking at (which are 6-wire). The only real difference is the A3977 board drives Bipolar, and the Linistepper drives Unipolar Motors. I guess it comes down to the question, will 6-wire unipolar motors make any more/less power wired bipolar over unipolar, or will the torque stay the same?


As for the Breakout Boards, there's just a bunch listed off www.PMinMO.com

http://pminmo.com/PMinMOwiki/index.p...4axisinterface
http://pminmo.com/mhelsinterface/mhelsinterface.htm
http://timeguy.com/cradek/cnc/stepper-drivers
http://pminmo.com/db25/basicBOB.htm

I guess I'm just wondering which of those is the "best"?


Thanks,


- Jesse

[probinson]

Hi Jesse,

I don't have time to review the various links but, as nobody else has answered you, I'll touch on the torque issue.

The unipolar stepper is basically a bipolar stepper with a center tap on each of the windings. This makes the drive circuitry simpler because instead of a full bridge for each coil, power is applied to the center taps and the driver chooses polarity by connecting the appropriate end of the coil to ground. Only being able to use half of the windings at any given time is the price you pay for this drive simplicity. Less efficent use of the winding space gives a unipolar stepper motor less torque than the same motor would have in a bipolar configuration.

Pete

[Jesse B]

Originally Posted by probinson Hi Jesse, I don't have time to review the various links but, as nobody else has answered you, I'll touch on the torque issue. The unipolar stepper is basically a bipolar stepper with a center tap on each of the windings. This makes the drive circuitry simpler because instead of a full bridge for each coil, power is applied to the center taps and the driver chooses polarity by connecting the appropriate end of the coil to ground. Only being able to use half of the windings at any given time is the price you pay for this drive simplicity. Less efficent use of the winding space gives a unipolar stepper motor less torque than the same motor would have in a bipolar configuration. Pete

Okay, thank you very much. I've narrowed down all those options to a couple things, and this helps