Would like some advice on upgrading to a variable speed DC motor in a Thorens DC166 MkII

I was thinking about replacing the motor in my TD166 MkII with a brushless DC motor. The main aim is electronic speed adjustment to replace the mechanical belt-shifter.

Has anyone tried this? I did find the Origin Live and would like to built my own "cheaper" version of that.

Was thinking of using PWM speed control, possibly with hall sensor. Or an Arduino-based controller.

Can use soft-start or keep the original clutch-pulley

Is this a good idea? I would appreciate any advice on the best motor/pulley to use and reliable speed controllers.

Alternatively; let me know if it is a stupid idea and that I should just leave it alone 🙂
 
Here's a couple of pictures.
I have built an oak plinth and dampened the inside. Cart is a Shure M97 with Jico SAS/B stylus.
 

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The BLDC drive uses electronic commutation, that can be a source of noise, be careful about that.

I think there are threads about this conversion (on other tables) here on diyaudio, just go through those posts for a better idea of the work involved.

And you need not go full digital, a multi turn pot on the feedback loop, with a digital display, is quite enough to control the speed, though tiny controllers are very cheap these days.

You might as well go whole hog and upgrade the bearing to a ceramic ball, or otherwise make it smoother to reduce rumble from the mechanism.
 
No problems with rumble since I built the new damped plinth.

I found some of the threads you were talking about. It doesn''t seem like a very popular or easy mod. Maybe I should take the hint.
I thought it would be handy to switch between 33 and 45 at the flick of a switch rather than shifting the belt. I've had this TT from new (>35 years), I should probably leave it alone. I was hoping someone had successfully modded the TD166 (motor), that would be encouraging.
 
Another motor worthy of consideration is this:-
https://www.ebay.co.uk/itm/235536635718 ... 5735062836
It is a 3 phase motor, with decent sleeve bearings, and when driven properly runs almost completely silently, and with little or no vibration.
Either Pyramid's SG4 https://www.diyaudio.com/community/...rator-for-turntable-motor-drive.298018/latest
or Richb's Superspin https://www.diyaudio.com/community/...tor-for-synchronous-motor-drive.365849/latest
would provide an excellent source of 3 phase signals.
For those not into stuffing pcbs there's also this:- https://www.ebay.co.uk/itm/363357898050 , not as flexible, but still
a worthwhile alternative. For all of these you need to add 3 small power amplifiers; I've used these with some success:-
https://www.ebay.co.uk/itm/186363266824 ... 4413503947
As a completely 'off the wall' alternative have a look at these:- https://www.ebay.co.uk/itm/394878303787
no amps needed, just a 12v wallwart and a replacement potentiometer (i used a 10 turn cermet trimmer).
 
i use an Arduino-type board + plug in bldc driver board + SimpleFOC software library to generate 3-phase sine waves (or SpaceVector waves) to drive my BLDC motor. It is silent, and achieves extremely low speed variation.

$50 in motor control hardware + $100 for a nice strong low coggimg bldc motor (like a 4pole or 8pole BLDC from Anaheim Automation) is pretty awesome.

i have used both Arduino and STMicro Nucleo boards.

20250308_141744.jpg
 
Another motor worthy of consideration is this:-
https://www.ebay.co.uk/itm/235536635718 ... 5735062836
It is a 3 phase motor, with decent sleeve bearings, and when driven properly runs almost completely silently, and with little or no vibration.
Either Pyramid's SG4 https://www.diyaudio.com/community/...rator-for-turntable-motor-drive.298018/latest
or Richb's Superspin https://www.diyaudio.com/community/...tor-for-synchronous-motor-drive.365849/latest
would provide an excellent source of 3 phase signals.
For those not into stuffing pcbs there's also this:- https://www.ebay.co.uk/itm/363357898050 , not as flexible, but still
a worthwhile alternative. For all of these you need to add 3 small power amplifiers; I've used these with some success:-
https://www.ebay.co.uk/itm/186363266824 ... 4413503947
As a completely 'off the wall' alternative have a look at these:- https://www.ebay.co.uk/itm/394878303787
no amps needed, just a 12v wallwart and a replacement potentiometer (i used a 10 turn cermet trimmer).
I might experiment with that motor and the ""off the wall" controller. What value of trimmer pot did you use? I was thinking of using two pots - one set for 33 and one for 45 - and switching between them. I think that will work.

I also found this motor...

Nidec 24H

Looks like it might be a good option (if it fits).
 
Plenty of good suggestions. The one thing I am stuck on is finding a suitable pulley. There are plenty of toothed pulleys but obviously not suitable (unless I stick it in a lathe and machine the teeth off).

This motor...

Nidec 27H060D180

Has a 3.15mm shaft (eek)

This one...

Nidec 24h

Has a 6mm shaft but it has a flat - I guess it could work if it has allen screws in the pulley

Any thoughts on a pulley to suit one of those. There's flexibility on diameter as the motor is speed-adjustable. Not too big though, I guess.

I'm trying not to spend too much in the "experimenting" phase just because the components might not be suitable.
 
i use an Arduino-type board + plug in bldc driver board + SimpleFOC software library to generate 3-phase sine waves (or SpaceVector waves) to drive my BLDC motor. It is silent, and achieves extremely low speed variation.

$50 in motor control hardware + $100 for a nice strong low coggimg bldc motor (like a 4pole or 8pole BLDC from Anaheim Automation) is pretty awesome.

i have used both Arduino and STMicro Nucleo boards.

View attachment 1468862

This is very tempting but I don't know if it is better to stick with one of the simple PWM controllers. Is there any advantage to using a programmable controller? I'm guessing you can set up things like soft-start and braking. Does it give you real-time speed locking?

I'm having trouble sourcing decent motors here in Australia (like the ones you suggested). Do you have an opinion on the ones I linked above?
BTW: Did you do your mod on a Thorens deck?
 
I used 10k 10 turn trimpots
Using two pots and switching between them for 33 and 45 rpm works fine; what I'm not so sure about is the consistency of the speeds.
I'll have to fit it to a TT and try it out. The other aspect of this controller is how much electrical noise it generates, and how easy it is to screen it.
 
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