Simple DC motor control
- Thread starter martin clark
- Start date
JemHayward
pfm Member
Now this is what I want (I think) - the google translation is a bit unfathomable, but this PSU seems to tick all the boxes. I've moved from a Lingo (mk1) to a DIY Armageddon clone with variable outputs and have found that the exact voltages for each winding do seem to make a difference to vibration. My PSU uses a frame transformer and it does buzz slightly, so I need to rebuild it / redesign it, and feel that single speed may be a bit of a pain, so was thinking of other motors PSUs etc.
How do I go about getting hold of this unit, and what are the options?
sq225917
Bit of this, bit of that
i listened to the motors , i chose . simple as . As advised i have no desire to validate my decisions by convincing others , its hifi not marxist theory or parenting praxis
Well done you for being so self assured, congratulations.
Jem you have a pm, I wouldn't want Gerald to think I'm using the forum as the basis for some turntable speed militancy activity.
JemHayward
pfm Member
Many thanks... have sent PM to him...
What experience do listees have in fitting "alien" motors to the LP12? I'd quite like to go to 24V for convenience and eventually, if I can get the vibration down to almost zero, look at fitting the motor to the sub-chassis - but that is then re-designing the turntable.
I am currently using a 24v Premotec (the one that Rega uses) on my "SkeletaLinn".
The TT itself is something I built using core Linn parts - but designed to take a 12" arm that I fell in love with, when I heard it Christmas, 2012.
I started off with a stock Linn 110v Premotec motor (with attached crowned pulley), driven by the original resistor/cap power supply fed straight from the mains.
Then I came across the "Number9 TT" speed controller, developed by Steve Tuckett here in Oz. He designed this to drive the 24v Rega Premotec ... so I had to get someone to machine a Linn-equivalent pulley for the Rega motor. One of the good things about the #9 TT speed controller is ... you can adjust the mains Hz (which controls speed) by 0.001Hz increments - so if the machined pulley is fractionally too wide or too narrow, this can be compensated for.
Another feature of the #9 TT speed controller is you can adjust 2 parameters (phase between the 2 motor circuits and running voltage) to minimise vibration - so you could certainly mount it on the subchassis of a standard Linn. However, I suggest this is of doubtful benefit.
I am rapt with this speed controller so will be selling my stock 110v Linn motor.
Regards,
Andy
JemHayward
pfm Member
Struggling to find any info on this on the 'net - their website is a bit patchy... If there is an off the shelf offering at a sensible price - that may be more tempting than DIY.
Jem, yes, Steve is not putting much effort into his web-site.
However, he is targeting this speed controller as a product in its own right (in addition to the #9 TT itself), at TTs which use AC motors. So Rega (given the 24v motor) but also Linn & Thorens. I bought his prototype unit - the one he is currently working on is "smarter", with a touch-sensitive screen which enables you to program the various control parameters (with mine, you have to plug into a PC and use PuTTY to download the parameters - simple enuff but a touch-screen is sexy! ).I'm sure Steve won't mind me providing his email address to potential customers: [email protected].
Good luck,
Andy
I am using a tangospinner 3 pulley model which is a 6061-T6 aluminium subplatter, the spindle and bearing is I believe 316L stainless steel. The bearing housing and ball is a PEEK ceramic unit so rather than mess about with thicker oil' I was thinking a magnet between the top plate (perhaps milled back a few mm in a rebate so it sits flush) and then glued in place.
N facing top? Opposite side to motor and away from tonearm?
Premotec and platter is here, decided on a ball end cap/thrust plate as I totally get the spindle could be chattering up and down, why I think most TT makers put one on there.
Paul R
pfm Member
It doesn't matter which way around. The miracle of eddy currents does the work. Not too close to the cartridge, otherwise I don't see that it matters much.
Ages ago I did some experiments with spinning the platter up to a speed by hand and timing the reduction to a lower speed. 78 to 33 was easy with a strobe. So I know the magnets do drag. And in use you get a tiny, but measurable, reduction in speed, due to the belt being slightly stretched, and therefore becoming thinner.
More things you did not need to know coming right up!
Paul
Ages ago I did some experiments with spinning the platter up to a speed by hand and timing the reduction to a lower speed. 78 to 33 was easy with a strobe. So I know the magnets do drag. And in use you get a tiny, but measurable, reduction in speed, due to the belt being slightly stretched, and therefore becoming thinner.
More things you did not need to know coming right up!
Paul
As I am rebating out an aluminium top plate I ought to consider not only placement but size of the magnet, I asume an ordinary iron magnet disk one or perhaps two placed so that they are nowhere near the motor or the cart
On my TD124 the magnet was a brute force speed control closer=slower/further away=faster! I assume this is just something to slip under the subplatter so it does not touch (obviously) or affect the motor?
The subplatter I am using is a tangospinner with three rings on one pulley on one spindle position (not pt style, three spindles). For the top plate I have a nice billet of 10mm 8083 languishing in the woodshed that came up quite well after we bead blasted it. I was going to get some disks and CNC a rebate and either epoxy or silicone them in place.
Sound reasonable?
On my TD124 the magnet was a brute force speed control closer=slower/further away=faster! I assume this is just something to slip under the subplatter so it does not touch (obviously) or affect the motor?
The subplatter I am using is a tangospinner with three rings on one pulley on one spindle position (not pt style, three spindles). For the top plate I have a nice billet of 10mm 8083 languishing in the woodshed that came up quite well after we bead blasted it. I was going to get some disks and CNC a rebate and either epoxy or silicone them in place.
Sound reasonable?
sq225917
Bit of this, bit of that
The LP12 bearing happily runs on silicon oil, like RC car diff fluid, available on t' Bay. My deck spins down from 33 1/3 in about 2 revs if I flick the belt off quickly, so there's quite a bit of drag in the system.
To be honest, viscous drag and a real adjustable TT-psu made the most profound difference to my vinyl replay in years of tinkering.
To be honest, viscous drag and a real adjustable TT-psu made the most profound difference to my vinyl replay in years of tinkering.
I might play with thicker oil, although I am using a PEEK bearing I toyed with rebating a magnet and played with motor/pulley movement and so on but thicker oil sounds less hassle, fewer CNC cuts to potentially get wrong too, although I will whack out a proto template first from balsa just to be sure it all fits snug.
The hercules it's also adjustable which Is nice, I just noticed it has trimmer pots, so rigid 10mm top plate, secure motor mounting rebated into a tight well, thicker oil and see where it takes me from there. Premotec arrived, spindle thrust pad arrived it's looking a bit pink triangle-y here, neither borrowing bits and cues from all sorts of designs, nothing original nor is any attempt to be -- but that is the story of my life.
When I get all the bits I will double/triple check measurements with callipers, quarter mil play where it's needed and whack out a slab of metallic goodness...
The hercules it's also adjustable which Is nice, I just noticed it has trimmer pots, so rigid 10mm top plate, secure motor mounting rebated into a tight well, thicker oil and see where it takes me from there. Premotec arrived, spindle thrust pad arrived it's looking a bit pink triangle-y here, neither borrowing bits and cues from all sorts of designs, nothing original nor is any attempt to be -- but that is the story of my life.
When I get all the bits I will double/triple check measurements with callipers, quarter mil play where it's needed and whack out a slab of metallic goodness...
Daniel Quinn
Banned
Fox where is the platter from , is it new/ off the shelf or is it a PT . If it is the former is it the same dimensions as a pt . on the look out for a spare
Ah, well it's is purchased now and it's by all accounts a fairly decent PSU so I am set, I am hoping it stays fixed at 45 but 33 would be useful. as soldering is beyond me now snap together pre- made DIY solutions (like the centre speaker) was always going to be the way.
I notice all Regas have the bearing up by 2mm due to a collar and hole. As I am cncing into 10mm of ally I may rebate the bearing to sit flush. It is also a canny way to equalise the extra 1.10mm needed for the motor studding that go on the underside.
I notice all Regas have the bearing up by 2mm due to a collar and hole. As I am cncing into 10mm of ally I may rebate the bearing to sit flush. It is also a canny way to equalise the extra 1.10mm needed for the motor studding that go on the underside.