Hi all, I’m new here and looking for some advice. I’m investigating options for a motor to drive a vinyl turntable. Key requirements are low noise, low torque rippple, low speed (nominally 250RPM) and very accurate control. Most turntables on the market today use a twin-phase AC synchronous motor that is built a lot like a stepper, just with optimised magnets to limit the ‘bumps’ in its steps. The motor is driven by a sine wave AC frequency at the desired voltage giving. very accurate rotational speed, and by adjusting the phase angle you can achieve very low noise.
But these motors are expensive. I figure since a stepper motor is essentially the same construction it should be usable in the same way. Looking at the ROB-10551, which has a 7.5-degree step angle. Given a 50Hz frequency, the two coils combined give 100 pulses per second, 2 50Hz sine waves at a 90-degree phase angle to give a 15-degree step angle. 50 Cycles per second therefore gives 6000 pulses per minute and 90,000 degrees. 90,000 divided by 360 equals 250RPM.
Has anyone tried this with the above stepper? Is there a means of determining the torque ripple if the motor is used in this way? Any and all input would be greatly appreciated.