Who is interested in a groupbuy of Mark Kelly's DC controller PCB and related parts

[ARAD]

Hi Bas,

in order to keep things simple, I will get the parts for the pcb myself... but count me in for a pulley.

Regards,
Andreas

[markgall]

Hi,

I'm interested in a PCB, motor and pulley also. Maybe the whole works depending on the cost and funds available at the time.

Mark

[bigo]

Depending on the cost, the works, including deluxe parts, would be of interest to me.

[ZUM911]

One complete set for me as well, thanks.

[Mark Kelly]

I need to clarify a couple of points regarding motors. There are two DC motors mentioned in the article, Maxon part no #110191 and # 226764. The first is OK for higher speed applications (say 600 RPM), the second is better for lower speeds (say 300RPM).

If you are not already committed to one speed, you should note that belt creep increases with step down ratio, so 300 RPM is better than 600 RPM. The motor / controller is good enough that belt creep will become the dominant source of speed variation with a standard soft rubber belt.

Given that the motors come from Maxon in Europe, perhaps one of the European participants can look at sourcing them - if I do it I have to wait 4 weeks for delivery to Australia.

Lastly in answer to Kohjin Yamada

Originally posted by Kohjin Yamada
I join in for motor, controller, pulley.

'motor' meant "EC Motor Drive (3 phase)" ?

The motors involved here are standard brushed DC motors. I have given up on the EC motor, it is too expensive. If anyone else wants to play with it I would gladly sell the existing EC motor and the control boards for half what it has cost me.

[Tonyb]

Hi Mark,

I may be interested in your EC motor. Drop me a line.

Regards,

TonyB

[Matt Rowland]

Hi Bas

I would like a pcb and maybe a pulley if it is suitable for a linn sondek and a maxon RE-max 29mm 226756 (36v).

Cheers


Matt

[Mark Kelly]

Originally posted by Matt Rowland
Hi Bas

I would like a pcb and maybe a pulley if it is suitable for a linn sondek and a maxon RE-max 29mm 226756 (36v).

Cheers


Matt

The controller will work with the lower voltage maxon motors but not quite as well as the higher voltage ones. With the motor you specified I calculate a speed variation of about 0.1% per ohm of effective impedance for a drag force of 10mNm at the platter edge at 300 RPM. The two motors I specified give better performance than this - the 226764 about 0.01% and the 110191 about 0.05%, if the 110191 is used at 600 RPM it improves to about 0.02%. As mentioned above at these levels belt creep becomes more important than motor variation.

[arnoldc]

Hi Mark,

I'm currently using a Clearaudio Champion Magnum (thick platter). Do you think the 226764 can drive it well?

[Mark Kelly]

Originally posted by arnoldc
Hi Mark,

I'm currently using a Clearaudio Champion Magnum (thick platter). Do you think the 226764 can drive it well?

Basic answer: Yes.

DC motors deliver a large amount of torque at lower speeds so accelerating the platter is not a problem.