High quality AC turntable motor

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.

Dear Mark,

Do you offer a kit or schematics for your single-phase controller? I have a Lenco for which I would desire a motor controller.

Redglobe,

From a cursory glance, I would say that the Sound Carrier unit is very similar to either the Walker or the SDS (with the added ability to trim output voltage). Hence, no - I don't believe the unit to offer full parametric adjustment, far from it in fact. The Heed Orbit would fall into this same category as well.

To give you a better idea, my Kelly controller has approximately seven trim pots that can be adjusted to not so subtle effect. Of course, this excludes the speed selector switch, frequency setting 'switches' and the on/off switch. I do not, however, have a fancy meter on the front of my controller ;-)

Grbluen2,

I'm afraid I can't be more specific about building a parametric two phase controller from the ground up. The easiest way out would be to use two MP3 players with continuous sinusoidal waveform loops (of differing frequency for speed selection) fed through a cheap (maybe class D) amplifier such that one could vary the output amplitude (voltage) for each phase (IMO, this is the most important parameter to adjust). While this doesn't give one full parametric control, it is essentially the idea behind the first controller I mentioned (http://www.soundbound24.blogspot.ca/). It uses a chip which contains the command set for generating sine waves of varying frequency (speed), lagging one phase behind the other, changing amplitude and (were the builder to incorporate it) varying harmonic distortion components. In all, he's on the right path. The devil of course is in the details.