I have just completed a turntable but have issues with the motor. I have tried 3 different motors, all with different results and neither of them fully satisfy me. 2 of them are Hurst AC motors and one was a SAIA-Burgess AC motor. The Saia motor was good but when I added mass to the platter (not shown in pics), it didn't have enough torque to keep the platter spinning.
The 1st Hurst motor I tried was the best but it was very noisy and had a loose upper bearing problem. I have spoken with several motor companies (Papst, Hurst, Maxon, Saia-Burgess) familiar with turntable applications but in order to get a motor from them, you have to wait weeks, and even then the price is high.
I would like to try a DC approach with controller but I am an electronic moron. I am however mechanically inclined and own a machine shop which is where I designed and built everything for this table. If anyone can build me what I need, I will trade my machining efforts for the work. You can email me or respond in this thread. I want a good motor, AC with power supply is also welcome.
The 1st Hurst motor I tried was the best but it was very noisy and had a loose upper bearing problem. I have spoken with several motor companies (Papst, Hurst, Maxon, Saia-Burgess) familiar with turntable applications but in order to get a motor from them, you have to wait weeks, and even then the price is high.
I would like to try a DC approach with controller but I am an electronic moron. I am however mechanically inclined and own a machine shop which is where I designed and built everything for this table. If anyone can build me what I need, I will trade my machining efforts for the work. You can email me or respond in this thread. I want a good motor, AC with power supply is also welcome.
An externally hosted image should be here but it was not working when we last tested it.
Hi,
I don’t think the problem is the motor. Usually you need very little power to keep the platter spinning, even if it is heavy. The problem is more the bearing that has much friction. Maybe you should rethink about that. And another point:: more friction usually means more noise from the bearing.
And yes, delivery times can be very long sometimes. Ordered once a small brushless DC servo motor from Pittman and that took 12 weeks.
Just my 2 cents
Re: Re: Turntable project completed but need motor assistance.
THe bearing is not my problem. It is composed of 2 sintered bronze bushings, hardened and ground shaft, and ceramic ball. All friction surfaces are ground to 8 micron finish and the bearing clearances are extremely close. The platter spins beautifully with minimum friction.
I tried all 3 motors out on my Rega P3 table before making the one you see in the picture. I did this so I would have a working and proven reference, rather than an unknown.
Yes, the motor doesn't need a lot of torque but the small Saia-B motor is basically a "toy" motor with 0.9 cNm torque.Pjotr said:
Hi,
I don’t think the problem is the motor. Usually you need very little power to keep the platter spinning, even if it is heavy. The problem is more the bearing that has much friction. Maybe you should rethink about that. And another point:: more friction usually means more noise from the bearing.
And yes, delivery times can be very long sometimes. Ordered once a small brushless DC servo motor from Pittman and that took 12 weeks.
Just my 2 cents
THe bearing is not my problem. It is composed of 2 sintered bronze bushings, hardened and ground shaft, and ceramic ball. All friction surfaces are ground to 8 micron finish and the bearing clearances are extremely close. The platter spins beautifully with minimum friction.
I tried all 3 motors out on my Rega P3 table before making the one you see in the picture. I did this so I would have a working and proven reference, rather than an unknown.
I didn't remove the Premotec motor from the P3 to try with my new table. What I did was use the 3 motors with my P3 table since I already knew what the P3 sounded like with its own Premotec motor. I was able to detect difference in performance from a known source. I did this prior to building this table.Pjotr said:Ok, it was just a thought
Cheers
Hi,
Did you already have had a look here?
http://www.turntable-power-supply.com/turntable_power_supply_outline.htm
Cheers
Did you already have had a look here?
http://www.turntable-power-supply.com/turntable_power_supply_outline.htm
Cheers
Thanks for the link.Pjotr said:Hi,
Did you already have had a look here?
http://www.turntable-power-supply.com/turntable_power_supply_outline.htm
Cheers
I have already checked that option out. I know someone who has that motor/p. supply and had trouble with it. He just sent it back to have it fixed. It is rather expensive too so I'm still looking.
Hi Vinyl-Addict
Just a thought, but have you tried using the motor from a cheap japanese belt-drive tt to use while working out what you need?
You have a magnificent piece of work there, and I imagine you would like to use only the best to power it, but some of the motors supplied in 70s and 80s import tables were quite good.
And, they can be had for a few $ form any thrift store.
Another idea I have been kicking around is using a direct-drive tt motor outboard to drive the platter using the same size pulley on each end of a belt. Very high grade motor, speed controlled, and again available for $25 or $30 from a junk store.
You can email me if you want to explore this idea further.
Cheers
Jess
Just a thought, but have you tried using the motor from a cheap japanese belt-drive tt to use while working out what you need?
You have a magnificent piece of work there, and I imagine you would like to use only the best to power it, but some of the motors supplied in 70s and 80s import tables were quite good.
And, they can be had for a few $ form any thrift store.
Another idea I have been kicking around is using a direct-drive tt motor outboard to drive the platter using the same size pulley on each end of a belt. Very high grade motor, speed controlled, and again available for $25 or $30 from a junk store.
You can email me if you want to explore this idea further.
Cheers
Jess
Finally....
Well I finally got a prototype DC drive built with a Maxon motor.
It works very well and will be even better when we finetune a few things. The drive was designed by a kind gentleman in Australia. He shipped the boards to me last week and I assembled & installed everything into the housing.
The current motor is a Maxon 110191, pictured here inside the custom motor pod I machined but we are going to build an even more sophisticated drive in the near future for even greater performance.
I don't think he is a member of this forum, but thanks to him I finally have something to work with.
Well I finally got a prototype DC drive built with a Maxon motor.
It works very well and will be even better when we finetune a few things. The drive was designed by a kind gentleman in Australia. He shipped the boards to me last week and I assembled & installed everything into the housing.
The current motor is a Maxon 110191, pictured here inside the custom motor pod I machined but we are going to build an even more sophisticated drive in the near future for even greater performance.
I don't think he is a member of this forum, but thanks to him I finally have something to work with.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Description of function.
This resistance is selected and adjusted on the speed control board. The output voltage is adjustable from 1V to 16V.
The speed control board has a switch(center) to select between 2 sets of adjustments. This switch points toward the relevant pots that are active, 33 1/3 or 45. There are 2 multiturn pots on the board for coarse adjustment and 2 pots mounted on the front panel to finetune speed for both 33 1/3 and 45.
An IC pre-regulator is used to smooth the incoming DC. The smoothed DC is passed to a constant current source set at 200ma which passes this current to a shunt regulator which controls the output voltage according to the resistance placed between the base and collector of the control transistor.winggo said:
This resistance is selected and adjusted on the speed control board. The output voltage is adjustable from 1V to 16V.
The speed control board has a switch(center) to select between 2 sets of adjustments. This switch points toward the relevant pots that are active, 33 1/3 or 45. There are 2 multiturn pots on the board for coarse adjustment and 2 pots mounted on the front panel to finetune speed for both 33 1/3 and 45.
motor
I remember your thread from AA, and was recently wondering how things went with your motor issues. It looks as if MK came through with flying colors. He's the VA's boy genius, and a real asset to the forum-for me, unfortuneately, reading his posts is like reading a foreign language! Apparently he's going to be offering PC boards to help with the assembly of his controllers. Congrats on one of the most beautiful turntables I've ever seen.
I remember your thread from AA, and was recently wondering how things went with your motor issues. It looks as if MK came through with flying colors. He's the VA's boy genius, and a real asset to the forum-for me, unfortuneately, reading his posts is like reading a foreign language! Apparently he's going to be offering PC boards to help with the assembly of his controllers. Congrats on one of the most beautiful turntables I've ever seen.
Re: motor
Thanks very much for the kind words John. MK is very knowledgable and was willing to offer his talent to get me something to work with. The downside is that he is on the other side of the planet so working things out takes time. I think he has a lot of things going on right now so this project took a lot longer than he expected.johnbrown said:
Your table looks very cool. I am currently working on my pods, being i dont have a lath and no skills i am doing my best at making podsthat work and look cool. I have a simular problem with motors. I work for a copier company and have an unlimited access to motors but hthey are all large and most of the time noisy.
If it would all be possibile would a schmatic be avalible for me to construct a simular motor controll for my machine? I can then just bite the bullet on a maxon motor and have a working solution.
If it would all be possibile would a schmatic be avalible for me to construct a simular motor controll for my machine? I can then just bite the bullet on a maxon motor and have a working solution.
Thanks.........
If you don't have access to a lathe how are you going to make a pulley for the motor?
Unfortunately I don't have schematics for the DC drive because the person who designed it didn't offer it them me. I believe he is going to be posting it shortly on his website for DIY'ers to use but I don't know when this will happen. When it does I will send you an email to let you know. For now, keep working on your project and use a decent AC motor since they are very easy to implement.fortytwo said:
If you don't have access to a lathe how are you going to make a pulley for the motor?
I was figuring that ince i got the motor and did the math (to use the most of the torque for my diameter). I would have a local machine shop just turn one out of brass or bronze.
I was wondering what you used for a belt. I ordered a 1/4 inch flat belt bu i fear it will be hard to line up perfactly because i made the mistake of putting a grove in my table for it to ride in.
Ed
I was wondering what you used for a belt. I ordered a 1/4 inch flat belt bu i fear it will be hard to line up perfactly because i made the mistake of putting a grove in my table for it to ride in.
Ed
Replies to questions on Motor Drive
The full answer to the question from Winggo depends on your definition of feedback. The primary regulator circuit does not use an active error amplifier nulling circuit, relying on the degeneration in the base emitter junction of the pass transistor in the shunt regulator. It does however also have a current compensation circuit (AKA I x R compensation or transimpedance compensation) which is a form of positive feedback.
The base emitter junction of any junction transistor has a negative temperature coefficient so the primary circuit suffers from a degree of thermal drift. I have therefore developed a new circuit which does use an active error amplifier in order to remove this effect, but this has not been installed yet.
I will be publishing full schematics for these and I hope to be able to make PCBs available. I have promised Bas Hornemann to publish in his on-line DIY Mag.
winggo said:
fortytwo said:
The full answer to the question from Winggo depends on your definition of feedback. The primary regulator circuit does not use an active error amplifier nulling circuit, relying on the degeneration in the base emitter junction of the pass transistor in the shunt regulator. It does however also have a current compensation circuit (AKA I x R compensation or transimpedance compensation) which is a form of positive feedback.
The base emitter junction of any junction transistor has a negative temperature coefficient so the primary circuit suffers from a degree of thermal drift. I have therefore developed a new circuit which does use an active error amplifier in order to remove this effect, but this has not been installed yet.
I will be publishing full schematics for these and I hope to be able to make PCBs available. I have promised Bas Hornemann to publish in his on-line DIY Mag.
Changes...
I've made a couple of significant changes in the past few weeks. I added 12 damped brass weights to the perimeter of the platter as well as 2 stage damped brass feet. I am also using roller balls under the platform that supports the assembly.
The Maxon DC motor is incased in the new Stainless/Aluminum pod. This has been a big stepup in performance. Future changes will be a larger main bearing with lower friction materials and a 2" thick platter. I am also going to try a flat belt.
I've made a couple of significant changes in the past few weeks. I added 12 damped brass weights to the perimeter of the platter as well as 2 stage damped brass feet. I am also using roller balls under the platform that supports the assembly.
The Maxon DC motor is incased in the new Stainless/Aluminum pod. This has been a big stepup in performance. Future changes will be a larger main bearing with lower friction materials and a 2" thick platter. I am also going to try a flat belt.
An externally hosted image should be here but it was not working when we last tested it.
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