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:)
 

EC8010

Ex-Moderator
2003-01-18 7:57 am
Near London. UK
fiacca said:
... 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! :D

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.
 
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