High quality AC turntable motor

Hi Lewm, I also would like to know how to acquire Mark Kelly's second generation AC motor controller.

If the controller does not split phase (relies on a capacitor in the motor to split phase), then I would expect that one is better off moving the belt on a pulley rather than electrically switching speed.

The motor controller for the Basis turntable does properly split phase in the controller, sending two separate power lines to the motor. The motor has to be modified in order to use the controller (one cannot just plug the motor into the speed controller).

Dear Larry, I think those are two different things (splitting phase, which is an advantage for an AC synchronous motor controller, vs electrically switching speed, which can be done by either controlling voltage or AC frequency or both, depending upon the type of motor). The only issue would be for an induction motor where there is kind of a plateau for voltage, below which the torque falls to zilch. Please anyone correct me if I'm wrong in this; motors are a complex subject that I hardly can claim to study on a daily basis. I am going on my fading memory of Mark Kelly's teachings.

Also, it's not "two separate power lines" strictly speaking. It's taking the sinusoidal AC wave form and generating a second one that is 90 degrees away from the first, so the motor is driven in quadrature. As I understand it, the more perfectly that is achieved, the smoother the motor will run. That's what a capacitor tries to do but does not do nearly as well.

Roscoeii and Redglobe, perhaps you can contact me by email. I cannot seem to find your respective email addresses. Let me know if you cannot find mine. I may be able to help, in any case.

Palasr,
First of all, thanks for shedding some light on a fairly dimly lit subject. I have recently upgraded to a Premotec 9904 111 31813, which is supposed to be a low noise, low vibration motor. I am happy with the motor, but have struggled with it's optimization. Assuming that I am capable of building a parametric controller as you have described, could you be more specific about the procedure. It seems to me that with the number of adjustments available, and without a suitable procedure, I would still be "taking a shot in the dark".
Thanking you in advance,
Don
Posted at 5:48 AM 28-NOV-2012

Mark Kelly here. I have no plans nor any desire to make or market a two phase controller for synch motors. As Palasr notes the support requirements for my design are too difficult to manage from Australia.

The controller to which LewM refers is a single phase unit for Garrard motors and their ilk.