Kudos to speed controllers

Dre

I sorry if I came across too strong, it's not your understanding of the situation to which I am taking exception. I guess I overstepped the mark but I'm not keen on my designs being called "similar" to others.

By the way, the reason that the single phase controllers have trouble with different speeds is an inherent feature of the phase shift capacitor. The capacitor value is equal to the square of the drive frequency (in radians per second) divided by the winding inductance. Since the winding inductance is fixed, if the capacitor is correct for one frequency (say 60 Hz for 33) then it must be wrong at any other frequency (say 81Hz for 45).

To answer your question, yes I am working on a new design. For a long time the development of the harmonic tuning concept was stuck because my analysis indicated that the effect should occur at the second harmonic but my measurements showed that third harmonic worked. It finally hit me as I drove home last weekend why this is so; I now have a clear path ahead.

To Jloveys: Your challenge, should you choose to accept it, is to find me a motor whose performance is not improved by a dedicated controller. I will gladly pay you $1000 each for them.

Mark Kelly

Agree! I recently added a motor controller by way of a PS Audio P300 unit which has the Multiwave II oscillator board. I am able to precisely control the motor speed in 1/8th Hz steps. Indeed, like you, I can see the stroboscope lines lock i.e. stop inching forward or backward when the speed is correct.

Another thing is that leveling the TT is an absolute must. I re-levelled my TT yesterday after what seemed a long time & boy, did I reap a reward.

Dear Mark: no challenge here. The answer is simple: the TD 124 motor.
Cheers,
Jean.

JLoveys

I disagree profoundly.

The 124 uses either a shaded pole single phase motor or the Papst three phase (one replaced the other).

Both of these are distinctly improved by a dedicated controller. Of course the controller involved is different in each case.

Mark, I stand ready and waiting for your new controller. I am just about healed up from kicking myself for not buying the last of your kits.