How to determine motor wiring

[mikemill]

I have a few motor grab-bags from Jameco. These are all 6-wire, 24V stepper motors and the cases are all effectively sealed. I can't track down anything that remotely looks like a datasheet for any of these either, so...

Does anyone have a somewhat foolproof way to figure out the wiring for these or is there some "standard" for stepper motors (sort of like there is for servos)?

Thanks
Mj

[dacflyer]

2 types of steppers that i know of..
1 type has a common and then branch wires for each step, they should all OHM out about the same ( if you found the common )
the other type i know of has 2 wires for each pole
so you should find 3 sets of continuity
hope i helped.

[philba]

there are a number of ways steppers are wired. to start with there is unipolar and bipolar. check this article for basics: http://en.wikipedia.org/wiki/Stepper_motor

Most likely, you have 2 phase steppers. you will find them to have 4, 5, 6 or 8 leads. 4 is bipolar (2 coils), 5 is unipolar with all 4 coils joined with a single common. 6 is unipolar and has 2 coils, each with a center tap. 8 has 4 coils. 8 wire steppers can be used unipolar or bipolar depending on how you connect them.

You can establish which wires have continuity by shorting a pair of wires together. If the stepper is harder to turn, then they connect. For a 6 wire motor, use ohms to determine which is the center tap (though you can usually tell when the tap wire is shorted to one end because it is easier to turn the motor than with both ends shorted).

Once you have figured out the wiring topology, measure the resistance of the coil and, assuming 5V, use ohms law to determine the current. That is the current limit. You can push higher voltage through the motor but limit the current. That gives you more power.

[MrAl]

Hi there,

Here is a schematic that might help. Because there are 6 wires
they are probably Unipolar motors, and that's mostly what
Jameco sells anyway.
To be sure, see if the resistance across each section of each coil is one
half of the resistance across both parts of each coil.

BTW, you can drive these as either Unipolar or Bipolar, but you'll
get less power using the Bipolar drive.

Also, the main spec of these motors is the max current rating, and
unless you know the correct operating voltage (24v is probably not
the real correct voltage) it is hard to determine max current. The
true operating voltages vary widely anyway, so it's hard to say
what voltage they really are, and the voltage rating isnt that
informative unless it is spec'd mainly to determine average current.
The max current (or average current really) tells you how hard you
can drive the motor without damaging it. If you dont know you might
have to try different currents and see how hot it gets. Use the
step size you intend to use in the final application.

[mikemill]

Thanks all! Hopefully I'll get time this weekend to figure out what these are.