I use Mark Kelly's Synchrotron AC-1 controller, which contains all of the aforementioned features (and then some) but has long since been unobtainable; this was a DIY Audio kit project from several years back. You bought the raw boards, bought the parts, understood the design's theory and you were basically on your own; you built the unit from the chassis on up - not a build for the novice. I admit, I've been spoiled by the controller's abilities.
Another possible candidate in the making is this gentleman's controller, based around a PIC/Atmal chip:
http://www.soundbound24.blogspot.ca/ (scroll down to the Bi-Onda controller). He seems to be on a hiatus, but I'm hoping he continues on the fascinating path he's on; his is the most promising and versatile design I've seen in a while.
I would gather that without upping the power handling of the output amplifiers, both this controller and my Kelly can't drive anything larger than say, 7 watts (the average synchronous motor in a TT is usually 3-5 watts).
There is also the Sander's speed controller over on Lenco Heaven: http://www.lencoheaven.net/forum/index.php?topic=2042.0 This appears to have applicability toward higher wattage motors (15-20 watts), and shaded-pole induction types as used in the Lenco, Garrard and others. I haven't gone through the entire post to tease out the details of the circuit, but it appears to cover the essential parameters. I'm still exploring the salient characteristics in this lengthy thread.
I've never had a Walker controller open to see what makes it tick, but I'm guessing it's about the same as the SDS. While a Linn Lingo has a nice sine wave synthesizer, it also doesn't allow for any parametric adjustment - despite the fact they're loaded with (unlabeled) trim pots.
While I advocate complete parametric motor adjustment, it's also a catch-22. You need some test gear like a multimeter and an oscilloscope to really maximize performance; a little too far this way or that with some settings and you can really mess things up (as in your motor stalls, vibrates and you become sad because your table no longer spins). This, I believe, is the reason nobody has a desire to market a motor controller which contains all the necessary parametric adjustments: the support issues would instantly turn into a complete nightmare since most folks simply aren't technically savvy enough reap the benefits or dig themselves out of the inevitable holes that would result.
Another possible candidate in the making is this gentleman's controller, based around a PIC/Atmal chip:
http://www.soundbound24.blogspot.ca/ (scroll down to the Bi-Onda controller). He seems to be on a hiatus, but I'm hoping he continues on the fascinating path he's on; his is the most promising and versatile design I've seen in a while.
I would gather that without upping the power handling of the output amplifiers, both this controller and my Kelly can't drive anything larger than say, 7 watts (the average synchronous motor in a TT is usually 3-5 watts).
There is also the Sander's speed controller over on Lenco Heaven: http://www.lencoheaven.net/forum/index.php?topic=2042.0 This appears to have applicability toward higher wattage motors (15-20 watts), and shaded-pole induction types as used in the Lenco, Garrard and others. I haven't gone through the entire post to tease out the details of the circuit, but it appears to cover the essential parameters. I'm still exploring the salient characteristics in this lengthy thread.
I've never had a Walker controller open to see what makes it tick, but I'm guessing it's about the same as the SDS. While a Linn Lingo has a nice sine wave synthesizer, it also doesn't allow for any parametric adjustment - despite the fact they're loaded with (unlabeled) trim pots.
While I advocate complete parametric motor adjustment, it's also a catch-22. You need some test gear like a multimeter and an oscilloscope to really maximize performance; a little too far this way or that with some settings and you can really mess things up (as in your motor stalls, vibrates and you become sad because your table no longer spins). This, I believe, is the reason nobody has a desire to market a motor controller which contains all the necessary parametric adjustments: the support issues would instantly turn into a complete nightmare since most folks simply aren't technically savvy enough reap the benefits or dig themselves out of the inevitable holes that would result.