[Donrecardo]

I have a stepper motor with 8 leads

I dont have a problem with which lead is which or how to connect them up as the data sheet is quite clear

The data sheet explains I can connect it up as either ....

1] A unipolar 4 phase

2] A bipolar with coils in series

3] A bipolar with coils in parallel

I guess each way of wiring it up has its own advantages / dissadvantages

could some one please explain what these advantages/dissadvantages are and why one way of wiring it is better than another

BTW my driver can drive both unipolar or bipolar

Its nothing to do with CNC its actually to power a compass in a flight simulator but when I googled " advice on stepper motors" it led me here

This is the motor http://www.arceurotrade.co.uk/projec...420484610M.pdf

Its number is AC420484610

Regards
Don

[BobF]

go to the gecko support page and download the stepper basics pdf. This is the best explanation I know of.

http://geckodrive.com/support.cfm

[Donrecardo]

Thanks bob that was very helpfull

Don

[James Newton]

That Gekodrive document actually does not cover Unipolar configurations, just different options with Bipolar. I have never seen a really good site that covers everything (I would love to hear of one) but in general, unipolar will run faster before missing steps and will have less torque than bipolar.

[Donrecardo]

Thanks for the reply James

I think perhaps unipolar might be the way for me to go as torque will hardly matter for my application

Amongst other things I wish to make a compass for my flight sim. This could be little more than a disk with points of the compass marked on it. or maybe an altimeter which is just a pointer that will swing around infront of a marked face .
Either way they would require very little torque but speed could well be important.

I hadnt realised untill I read the item on the geckodrive site that you dont run the motors at the stated voltage . When talking about bipolar I think it said you can run them at 3 to 25 times the rated voltage . Is this still true for Unipolar ?

Lastly it said to set the drive current to exactly half of the motor’s rated parallel current rating when using the series connection , but this was talking about bipolar again so if I use unipolar do I use the full rated current or half the rated current

Regards
Don

[ger21]

I hadn't realized until I read the item on the geckodrive site that you dont run the motors at the stated voltage . When talking about bipolar I think it said you can run them at 3 to 25 times the rated voltage . Is this still true for Unipolar ?

You run at higher voltages to increase speed. Speed is proportional to voltage, but the higher the voltage, the hotter the motors will run. It's best to run just enough voltage to get the speeds you need.

Lastly it said to set the drive current to exactly half of the motor’s rated parallel current rating when using the series connection , but this was talking about bipolar again so if I use unipolar do I use the full rated current or half the rated current

Regards
Don

Neither. Unipolar current is about 71% of bipolar parallel current.

[James Newton]

Gerry, I hadn't heard that 71% figure before. May I ask where you get that; if you have the time to tell me?

Don, in general, you want to run the lowest current that still gets the job done to reduce heating, especially when the motors will be holding a lot.

[ger21]

Gerry, I hadn't heard that 71% figure before. May I ask where you get that; if you have the time to tell me?

Not sure how it's derived, but look at any stepper spec sheet that lists both bipolar and unipolar ratings and you'll see that is how it works.