Power supply options for a Mitsumi Stepper Motor

rmcb

I have a Mitsumi Stepper Motor, part # 27964. It's described as a "4-Phase / 12 Volt Unipolar Stepper Motor."

The power requirements are listed as 12 VDC/90 Ohm.

Let me preface this by acknowledging that I'm ignorant when it comes voltage vs. amps types of questions.

I have an application that I'm currently using a servo for but I'd like to see if I can use the Stepper instead.

One of the attractions to using the servo is that it can be powered off of a 9 volt battery; small, compact, and easy to find.

One of the things that's kept me from using the stepper is that 12 VDC power rqmt.

The application doesn't require a lot of torque but possibly a bit more than the servo can handle.

If I don't need the full torque of the stepper, then can I power it with a smaller power supply; 9 V, 6 V?

IF so, is it safe to assume that at a lower voltage, the torque is less?


Thanks,

Ryan

Mark_T

rmcb wrote: »

I have a Mitsumi Stepper Motor, part # 27964. It's described as a "4-Phase / 12 Volt Unipolar Stepper Motor."

The power requirements are listed as 12 VDC/90 Ohm.

Let me preface this by acknowledging that I'm ignorant when it comes voltage vs. amps types of questions.

I have an application that I'm currently using a servo for but I'd like to see if I can use the Stepper instead.

One of the attractions to using the servo is that it can be powered off of a 9 volt battery; small, compact, and easy to find.

One of the things that's kept me from using the stepper is that 12 VDC power rqmt.

The application doesn't require a lot of torque but possibly a bit more than the servo can handle.

If I don't need the full torque of the stepper, then can I power it with a smaller power supply; 9 V, 6 V?

IF so, is it safe to assume that at a lower voltage, the torque is less?


Thanks,

Ryan

Small 9V batteries can't source much current so aren't going to drive a servo at full torque. Their voltage will drop lots too. Most servos are rated for 6V or 7.2V max, so you are risking electronics failure unless the particular servo is rated for 9V.

12V stepper at 9V will draw 75% of the current, but again small 9V batteries can't source much current, steppers require much more quiescent current than servos anyway - in fact they usually draw less current when moving! That 90 ohm unit needs 130mA per winding (so with full stepping that's nearly 0.3A constantly as two windings are driven all the time).