Kudos to speed controllers

I'd like to take exception to the statement that the Synchrotron AC-1 is similar to the Basis unit. Perhaps I should say "was", the AC-1 kit has been withdrawn permanently.

The AC-1 was an original design which used a different circuit topology to achieve different results. It offered a couple of features which are not offerred by any available controller (adjustable phase angle, adjustable harmonic tuning).

The similarlity with the Basis is simply that both are two phase controllers, but that's a bare minimum for any modern controller in my opinion.


Mark Kelly

Mark,

"The similarlity with the Basis is simply that both are two phase controllers"

This is exactly what my post was about.

I'm fully aware of the unique features of the AC-1 but that was not the purpose of my post. It was simply to point out the fundamental difference between two-phase units and those like VPI and Walker that are not two phase units.

I also have no idea how the Basis unit is adjusted to the motor when it is sent in to be modified and I simply won't comment on an aspect of the design that I'm not familiar with.

As you had stated, you pulled the kit permanently. It didn't make any sense to tout the unique aspects of the AC-1 when the readers of the post couldn't have access to it. It's kind of like a "look at what I have but you can't have it" comment. Personally, for me to say something along those lines would have been in very poor taste.

Although we haven't conversed via e-mail since I sent you comments of the results of the build, I hope you are working on something to offer in the future for those that didn't get the chance to enjoy your work.

Dre

I don't know really, but I have the strange impression that all those motor controlers are "band aids" for weak designed motors. why should a very good motor design and passive speed control need an electronic motor controler?
I seems like a very expensive solution.

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.