Hi there.
I have a stepper motor pm20s-020. There datasheet: http://www.nmbtc.com/pdf/motors/PM20S020.pdf
But this motor has only 4 wires not fifth. As I understand it the case is ground. I also have a ULN2003 and I tried to make this scheme:
Because of fifth wire is case (ground) and there shouldn't be 12 v?
So scheme like this
incorrect for me?
But the most important thing that I noticed is that the 4 wires connected to each other in pairs. The first and second interconnected with little resistance, and the third and fourth interconnected with little resistance. It turns out that motor has only two coil? How to make it work?
MarkT:
That picture on the datasheet suggests there are 5 terminals on the motor -
is your motor the same?
Its common for the same stepper (mechnically) to be available in a range
of different winding impedances and styles (4/5/6 or 8 wire).
Measure the actual winding resistances, with a multimeter, its the way
to find out.
As I said this 4 wires interconnected by pairs. So 1 and 2 wires interconnected and has about 10 ohm resistance (but this values is not accurate because I have bad quality multimeter) and 3 with 4 wires interconnected with same resistance. First pair (1 and 2 wires) and second (3 and 4 wires) not interconnected. Fifth wire (case of motor) with nothing connected
If that is true then it needs connecting to 12V, but check with a meter first.
I saw attachment (detail from some mechanism for this motor) which has 5 wires and fifth wire connected to case.
What I should check? About interconnected I wrote in previous message.
The wire to case could be safety ground? There is a rule which says exposed metal parts like cases etc should be earthed.
A meter should tell you if the fifth wire is connected to the motor coils.
Thank you. Your URL has info that this motor can be bipolar. My URL has info that it can be only unipolar. May be you are right because it could be like some modification. Full name of my motor: pm20s-020-hlar
Also your URL has photo and on the photo can see plastic detail on top that what about I said before. I have same and this detail has 5 wires and fifth wire connect to case of motor.
EDIT: I think your URL is correct. As I said coil has about +-10 ohm resistance. If look at this page bipolar motor has 8 ohm. My value so close to this value than value of unipolar motor about 100 ohm.
So now I don't understand why need fifth wire which connect to case of motor if it's bipolar? Just ground for other details maybe?
MarkT:
That picture on the datasheet suggests there are 5 terminals on the motor -
is your motor the same?
Its common for the same stepper (mechnically) to be available in a range
of different winding impedances and styles (4/5/6 or 8 wire).
Measure the actual winding resistances, with a multimeter, its the way
to find out.
As I said this 4 wires interconnected by pairs. So 1 and 2 wires interconnected and has about 10 ohm resistance (but this values is not accurate because I have bad quality multimeter) and 3 with 4 wires interconnected with same resistance. First pair (1 and 2 wires) and second (3 and 4 wires) not interconnected. Fifth wire (case of motor) with nothing connected
MarkT:
That picture on the datasheet suggests there are 5 terminals on the motor -
is your motor the same?
Its common for the same stepper (mechnically) to be available in a range
of different winding impedances and styles (4/5/6 or 8 wire).
Measure the actual winding resistances, with a multimeter, its the way
to find out.
As I said this 4 wires interconnected by pairs. So 1 and 2 wires interconnected and has about 10 ohm resistance (but this values is not accurate because I have bad quality multimeter) and 3 with 4 wires interconnected with same resistance. First pair (1 and 2 wires) and second (3 and 4 wires) not interconnected. Fifth wire (case of motor) with nothing connected
now I have another problem with that: