Variable DC power supply to drive TT motor - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th April 2009, 11:01 AM   #1
diyAudio Member
 
Join Date: Jul 2004
Location: Israel
Default variable DC poewr supply to drive TT motor

Hi all,

I'm looking for a stable lab varible DC power supply to drive a Maxon A-max motor driving my TT.

Found one for sale with:

Ripple & Noise: <1mV rms
Waves and noises: CV<0.5mV r.m.s, CC 3mA, r.m.s
Power effect: CV < 0.01 % +1mV, CC <0.2% + 1mA
Overload effect: CV<0.01% +3mV, CC<0.2% +3mA

could such a supply run my platter good and steady?

Thanks all
Ik
  Reply With Quote
Old 6th April 2009, 07:44 PM   #2
diyAudio Member
 
Join Date: Nov 2006
Default Variable DC motor control

I am presently using the Ultra DC motor control from Origin Live with the upgraded power supply.
It works fine and the actual parts inside the control unit are quite simple insofar as its seems to be a basic control set up.

But, I have just ordered from EBay a 30 Amp control unit .

http://cgi.ebay.com/DC-Motor-Speed-C...2%7C240%3A1318

Or - just do a search in EBay for DC motor control.
I bought for it a 12 V battery and cant wait to try it out; it should work very nicely - the only issue could be a finer pot to ajust the speed....

I will also be using a Maxon motor and a round belt from Clearaudio, driving the perimeter of the platter.
  Reply With Quote
Old 7th April 2009, 06:04 AM   #3
Werner is offline Werner  Europe
diyAudio Member
 
Join Date: Jan 2002
Location: Belgium
Sorry, but that's a Pulse Width Mode 'DC' supply, and such animals have no place in an audio system as their output voltage is essentially dirty.
__________________
bring back dynamic range
  Reply With Quote
Old 7th April 2009, 06:20 AM   #4
diyAudio Member
 
Join Date: Jul 2004
Location: Israel
THanks Werner,

As for the varible power supply driving a DC motor
Do the above figres give a "clean" DC to give a very stable speed?

IK
  Reply With Quote
Old 8th April 2009, 07:19 PM   #5
diyAudio Member
 
Join Date: Nov 2006
Thanks Wener:
''Sorry, but that's a Pulse Width Mode 'DC' supply, and such animals have no place in an audio system as their output voltage is essentially dirty.''

So, what would you suggest using, and do you have a linck ??
  Reply With Quote
Old 8th April 2009, 07:19 PM   #6
diyAudio Member
 
Join Date: Nov 2006
Default Variable DC Power Regulator

Found this kit on EBAy - seem it would be better than the PWM, since it seems to have a much better speed/dc varience tolerance ?

http://cgi.ebay.com/ws/eBayISAPI.dll...DLVI%26ps%3D54
  Reply With Quote
Old 9th April 2009, 06:34 AM   #7
Werner is offline Werner  Europe
diyAudio Member
 
Join Date: Jan 2002
Location: Belgium
That's the most basic regulator you can use with a DC motor for a turntable. Speed will depend on the accuracy with which you can set the trimpot VR1 (see schematic), and then speed drift will depend on what that potmeter does with temperature, age, and mechanical creep. It would be better to determine the required output voltage and then stagger VR1 with two resistors so that you can tune it more accurately. Also replace VR1 with a trimpot that has more turns, if such a thing exists.

For an OTT supply you may want to read this:



http://www.members.iinet.net.au/~qui...DCbrushed.html
__________________
bring back dynamic range
  Reply With Quote
Old 9th April 2009, 03:38 PM   #8
diyAudio Member
 
Join Date: Nov 2006
Default Motor control & trim pot

Werner, your response is much apreciated,

Actually I bought on EBay a maxon motor: Swiss Maxon 2642 13 pole coreless motor w zero cogging

http://cgi.ebay.com/Swiss-Maxon-2642...3286.m20.l1116


Am I right in presuming the above Maxon motor will also work for the DC motor control link you refer to?

As to your comments on the trim pot - they are most interesting...
I am presently using an Origin Live ( OL) Ultra dc motor control box + the Origin Live upgraded transformer.

I have found also that the OL 25 turn trim pot is sometime moody: the speed will sometimes suddendly change for no apparent reason for about 2 minutes or so & then resume its previous speed!?. When the speed changes, the trim pot does not react normally and it takes 2 to 3 full turn to change the speed - but by then the speed has been over corrected.....

I also looked at the online catalogue for pots at a local electronic store & they seem to be of all the same quality at about $1.00 Canadian each ?? So I wonder if & who sell best quality trim pots ??

So why am I getting another motor for my Oracle turntable ( I bought it without the original motor) ? -
Well, presently I am using 2 Origin Live DC motors, side by side, connected in parallell & driven by the OL motor control. I am also driving the platter around the perimeter for more torque. Oracle turntables are driven from under the platter, but, for the same motor, you get more torque driving the 12 '' perimeter instead of the 6'' inner perimeter.

I want a third motor so I can but it between the 2 motors in a V configuration. Thus the third motor would be at the bottom of the V and hopefully created more torque (turning in the opposite direction). The intent is to further reduce the stylus drag effect and also have the pleasure to try something different.

Since the OL stuff is quite good but very expensive, I am looking for a DIY motor drive system, as the middle motor would most likely not turn at the same speed as the 2 outside OL motors.
The 2 motors are presently connected in parallell to the Ultra control box. I do not see myself connecting a third motor that has different specs and would need to turn at a different speed.....

Any event, the article you refer to is excellent but quite tecknical for me.
It would be nice to find a decent DC motor control kit or ready made one at a reasonable cost to pursue this project.
  Reply With Quote
Old 9th April 2009, 05:25 PM   #9
Werner is offline Werner  Europe
diyAudio Member
 
Join Date: Jan 2002
Location: Belgium
1) Don't mix different motors. They'll only fight each other.

2) Don't connect multiple motors to the OL controller. The OL uses armature current feedback and when presented with two identical motors in parallel it is quite possibly unstable. Hence your 'trimpot problems'.
__________________
bring back dynamic range
  Reply With Quote
Old 9th April 2009, 08:33 PM   #10
diyAudio Member
 
Join Date: Nov 2006
Default 2 motors in // unstable

Interesting comment -

When the 2 motors are side by side - say 2 to 3 inches apart - I only get sudden speed variances occasionnally...

But, when I put the motors diametrically opposed, say, noon and six pm - then the motorisation becomes much more unstable ?

But another OL control and power supply is some $575 english pounds - such is the audio world of non DIY

I do have a maxon hall effect motor that is quite impressive - I may re-buy the control unit for it - this time I will try not o reverse the polarity!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Variable AC Power Supply Rino odorico Everything Else 12 14th March 2013 04:56 AM
Charging batteries with a variable power supply jacquesl Power Supplies 4 13th March 2013 07:52 PM
Bipolar Variable Power supply for protoboard jman 31 Power Supplies 10 24th March 2009 02:39 PM
Variable Pc Power Supply-2 (part1) 1..30v 0.15..6a gev Power Supplies 0 7th January 2008 07:46 PM
Digital Variable Power Supply jleaman Digital Source 13 13th April 2004 10:09 PM


New To Site? Need Help?

All times are GMT. The time now is 07:51 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2