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Sanghera
03-28-2004, 05:02 PM
Hi,
I was wondering which one is better, a unipolar or bipolar motor. I know there are probably a lot of variables like if you want more torque and whatnot, but lets hear about them.
Thank you for your time. :)

Sanghera
03-28-2004, 05:05 PM
Also, What does a tranlator and MOSFET do? I know these are probably very newbie questionsm but any info help.
Thanks.

Urgundiz
03-28-2004, 06:30 PM
Bipolar are normally more powerful for the same volts and the same amperes, due the current flows throug double length of wire, so creates double stronger magnetic field (explained the easy way). Unipolars are less powerful but easier to drive because the current only flows in one sense, so the electronics to drive it is less complicated. Thats are the main differences.

The translator 'translates' :rolleyes: signals from direction (left/rigth) and step (clock) to phase signal. phase signal is the rigth current impulses in the right order at the rigth wire of the stepper for making it to move.

Power to the windings are normally driven via transistors or mosfets. The mosfet is a semiconductor with specific technology capable of driving high amperes and high voltages, normally much more than power transistors. Other difference is that the transistors are current driven and the mosfets are voltage driven. other difference is that the voltage drop between mosfet terminals is much less (in general) than the drop at transistors, so they waste less power itself than similar rated transistors.


hope it helps
/U

Sanghera
03-28-2004, 06:42 PM
So, I have heard of people changing a unipolar driver to a bipolar or something or other. Does this have the exact same effect as having a bipolar setup? Do you still get the advantages? If so, I think that I might just get a unipolar setup and convert it to bipolar.
Thank you for the reply.
I really appreciate it.

Urgundiz
03-28-2004, 07:10 PM
You always can wire unipolar steppers as bipolars, just ignoring the unipolar common central wires, and the behaviour is almost equal to bipolar. Vice versa is not possible.

Unipolar drivers only drive unipolar (only one sense for the current), bipolar drivers only drive bipolar (two senses for the current). Yes, you can attach a unipolar stepper to a bipolar driver, but you must wire the unipolar stepper as bipolar stepper. You cannot wire a bipolar stepper to a unipolar driver in any way.

As you can see, the difference is the way you wire the stepper to the driver, not the driver behaviour. The behaviour of the driver cannot be changed by the user. So if you wire a unipolar stepper as bipolar stepper, you need a bipolar driver (driver=translator+power driving semiconductors).

So if you have a unipolar driver, for example a FET-3, you MUST use unipolar steppers, and drive it unipolar (the only way the driver knows how to drive).

If you have a bipolar driver, for example a gecko, you CAN use bipolar, or unipolar (wired as bipolar) steppers, and drive it bipolar (the only way the driver knows how to drive)


hope it helps
/U

Cold Fusion
04-01-2004, 09:22 PM
Ok, so I want to wire them bipolar parallel. I'm looking at this chart and am a little confused. Do I splice the 4 sets of 2 wires together?

http://www.coldfusionracing.com/CNC/pin.GIF

Ferenczyg
04-01-2004, 10:07 PM
Originally posted by Cold Fusion
Ok, so I want to wire them bipolar parallel. I'm looking at this chart and am a little confused. Do I splice the 4 sets of 2 wires together?

http://www.coldfusionracing.com/CNC/pin.GIF

You need to put the 4 sets wired the way every coil is created wiring two coils in parallel, so yes, you are grouping 6 with 5, 2 with 1, 8 with 7 and 4 with 3. Then:

A=6&5
/A=2&1
B=8&7
/B=4&3