Another absolute newbie TT motor question

fiacca · 14th January 2008, 11:24 AM

Good day all,
I have been searching the forums, I found a lot of threads, but I was unable to understand what I am supposed to do in order to choose a motor form my TT project.

The design will be with an heavy plynth and separate housing for the motor, of course with a belt drive.

I found a lot of discussions about AC vs DC motors, but, being totally ignorant about the matter, brush, brushless, controllers etc, means almost nothing to me.

At the moment it seems that the simplest option ist to buy a Premotec 9904 111 31813 AC motor; it should run at 250 rounds/min with no controller. Is that correct or advisable?

Driving the platter at its full diameter of about 310 mm I calculated that motor pulley should be around 41 mm in diam. is that correct or there a better way to proceed?

I have tons of questions, and please answer like you were speaking to a 3 years old

ciao and thanks Fiacca

EC8010 · 14th January 2008, 07:36 PM

Quote:

Originally posted by fiacca
... and please answer like you were speaking to a 3 years old.

What are you doing? Nothing? Well, stop doing it now! And leave the cat's tail alone!

The Premotec motor will spin at 350rpm on 50Hz mains, or 300rpm on 60Hz. Your pulley calculation sounds about right, but you will need to make it fractionally oversize to allow for belt slip. If you make a dedicated oscillator/power supply for it, you can make the frequency slightly variable and use that to compensate for inaccurate pulley diameter and belt slip.

A DC motor will spin faster, necessitating a smaller diameter pulley and probably making belt slip more of a problem. They are noisier than synchronous motors (both acoustically and electrically), but they're cheaper.

Nanook · 15th January 2008, 05:01 AM

There's a reason why Origin Live and many others have gone to DC motors.

Whether synchronous motor or dc types, if implemented correctly can sound very good.I think controlling the speed via voltage is one of the benefits of the DC types. Ac type motors require more complex electronics to feed it (or maybe a cd player to big power amp to power the motor accurately).

stew

fiacca · 15th January 2008, 07:14 AM

Thanks for your replie, clear and to the point.

I will try to find the best solution by trial and error

I will now look in the forum for DIY belts, to check what has been done.

Best regards fiacca

Nanook · 16th January 2008, 01:55 AM

out of artists plastic flexible tape. very strong, easy to splice...

stew

14th January 2008, 11:24 AM	#1
fiacca diyAudio Member Join Date: Mar 2003 Location: La Spezia	Another absolute newbie TT motor question Good day all, I have been searching the forums, I found a lot of threads, but I was unable to understand what I am supposed to do in order to choose a motor form my TT project. The design will be with an heavy plynth and separate housing for the motor, of course with a belt drive. I found a lot of discussions about AC vs DC motors, but, being totally ignorant about the matter, brush, brushless, controllers etc, means almost nothing to me. At the moment it seems that the simplest option ist to buy a Premotec 9904 111 31813 AC motor; it should run at 250 rounds/min with no controller. Is that correct or advisable? Driving the platter at its full diameter of about 310 mm I calculated that motor pulley should be around 41 mm in diam. is that correct or there a better way to proceed? I have tons of questions, and please answer like you were speaking to a 3 years old ciao and thanks Fiacca

15th January 2008, 05:01 AM	#3
Nanook diyAudio Member Join Date: Feb 2004 Location: Chinook Country.Alberta	ah, but perhaps more stable speed wise... There's a reason why Origin Live and many others have gone to DC motors. Whether synchronous motor or dc types, if implemented correctly can sound very good.I think controlling the speed via voltage is one of the benefits of the DC types. Ac type motors require more complex electronics to feed it (or maybe a cd player to big power amp to power the motor accurately). stew __________________ stew ☮ -"A sane man in an insane world appears insane."

16th January 2008, 01:55 AM	#5
Nanook diyAudio Member Join Date: Feb 2004 Location: Chinook Country.Alberta	I've made belts... out of artists plastic flexible tape. very strong, easy to splice... stew __________________ stew ☮ -"A sane man in an insane world appears insane."

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15th January 2008, 07:14 AM	#4
fiacca diyAudio Member Join Date: Mar 2003 Location: La Spezia	Thanks for your replie, clear and to the point. I will try to find the best solution by trial and error I will now look in the forum for DIY belts, to check what has been done. Best regards fiacca

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