Low Cost Turntable - Incredible Performance

@oberoniaomnia 

 record wobble frequency is at 1 Hz

Thanks - I had a brain fade and got my starting point wrong.  33-rpm is about 0.5-Hz, not 2-Hz.  My mistake.  Hopefully it shows I was not relying on AI (though maybe I should have been!)

@richardbrand ,

Are you saying a Jaguar made a 4000 km trip??!

How many breakdowns?

@thecarpathian 

"Grace, space and pace".

I am only saying that the GPS bit was still working near the start of the Eyre Highway!

When I was a kid, the owner of the local garage was a Jag nut.  The factory helped him a lot, because just after the Mark I was released, he floored the accelerator and collected a lot of scenery.  His diagnosis was that the engine rotated enough under torque that the engine drain plug fouled the steering mechanism.

(A couple of my friends independently still run Jaguars with V8 engines produced when Jag was owned by Ford)

@richardbrand ,

I think a Jag going 4000 km without breaking down is about as likely as a $299 turntable sounding "incredible"! 

May I ask, are you of Irish descent?

@lewm 

The treatment of cogging is either to use a lot of poles, so the impulses are very closely spaced, and there are other tricks of the trade that address the timing, all of which are very effective in rendering cogging inaudible

I have given a plausible (to me at least) explanation of when cogging may become audible even if it is virtually unmeasurable.

Take the Wilson Benesch Table One system as an example.  They claim wow and flutter is unmeasurable.  The direct drive motor is 15 inches in diameter, weighs 14-kg and has 21 poles, but nevertheless it does exhibit cogging to some degree - I’m not saying it is audible!:

The OMEGA Drive is a slot-less synchronous motor, delivering vanishingly low torque ripple and precise speed stability. The RMS value of the torque ripple is 0.001342 (N.m). The torque ripple includes all the components (like cogging torque and the current commutation and air-gap flux harmonics)