Can I use a computer PSU with a floppy/DVD motor drive TT? - Page 2 - diyAudio
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Old 6th July 2008, 05:48 PM   #11
EC8010 is offline EC8010  United Kingdom
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There's precious little difference between a stepper motor and a permanent magnet synchronous motor. When there's a difference, it's that the electromagnet pole pieces on a stepper are rectangular whereas a permanent magnet synchronous motor has triangular or at least trapezoidal pole pieces to reduce the cogging. The picture is of a Philips/Maclennan/Premotec motor
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Old 6th July 2008, 06:44 PM   #12
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Quote:
Originally posted by morepower4me

...I was trying to avoid going that route due to the extra steps of generating the sine wave as well as needing an extra amp and source...
There are many different ways to generate sine waves, including a function generator chip that I have used in the past and seems to still be available, the XR2206. The amplifier can be a chip amp and there is no need to get fancy with boards and premium components, as you will not be playing music through it.
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Old 7th July 2008, 11:58 AM   #13
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www.blueculture.com/floppyproject3.pdf

Try this.

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Old 7th July 2008, 04:59 PM   #14
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Wow, that breaks it down to where even I can read/understand it. Perfect!

Now, to circle it all back to the beginning... Can I power the floppy motor with the computers PSU. I don't mind the extra space, and it would seem the speed control aspect should still work. Any other issues? I think there is a 5v DC output. That seems to be what was used int he PDF.

I'd certainly prefer to not have to charge batteries, but if thats the best way, I am sure I can manage.
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Old 7th July 2008, 05:20 PM   #15
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Quote:
Originally posted by morepower4me
Now, to circle it all back to the beginning... Can I power the floppy motor with the computers PSU.
EC answered this in post #2. The issue at hand is: do you have enough pulleys and belts or can fabricate them such that you can be sure to run the motor at the original fixed rpm? If you are reusing what you have on hand you will need to vary the motor's speed, a predetermined voltage will not work for you.
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Old 7th July 2008, 05:59 PM   #16
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Quote:
Originally posted by leadbelly


EC answered this in post #2. The issue at hand is: do you have enough pulleys and belts or can fabricate them such that you can be sure to run the motor at the original fixed rpm? If you are reusing what you have on hand you will need to vary the motor's speed, a predetermined voltage will not work for you.

Very good point, I am afraid I missed that rather obvious reply!!

I have almost nothing on hand, so I guess the advantage is that I don't need to make anything else work with it!!

I am planning on using Altmann's bearing/platter/plinth idea (modified to look a little different) and then using the floppy motor mounted on its own detached base (to control tension) and driving it with sewing thread. The hardest part (IMO) will be pulley size.

What I am hoping to do, is mock up the motor pulley in wood, with a 'skewer' sticking out of the top and the motor mounting on the bottom. I am hope to bring it down to size by sticking the extended 'skewer' portion into a drill and using sandpaper to decrease the size of the pully until it spins the platter at the appropriate RPM. Once I have the size down, I'll just have the pulley machined from Aluminum.
I don't know how well that will all work... but it sounds good on paper!

If it all works (and decently well) I am planning to do a step by step pictorial to share my new knowledge with others (as you all have with me.)
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Old 8th July 2008, 05:59 PM   #17
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Received my 3.5" floppy drive...
Electronics madness starts tonight. Pics of my inevitable butchering to follow.
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Old 9th July 2008, 12:37 AM   #18
tubenut is offline tubenut  South Africa
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There are formulas posted on this forum for pulley size calccs somewhere, They all include some allowance for belt slip... I woud think that ally willhave different slip to wood...
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Old 17th March 2009, 01:47 PM   #19
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Default Pully calculation

The calculation is as follows (All values in mm):

((Platter_Diameter + Belt_Thickness) x 33.33/ Motor_RPM) - Belt_Thickness

Regards,
Bins.
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Old 25th March 2009, 04:04 AM   #20
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Hi,

I got another formula from this site. Please have a look:

Platter Diameter = PD in mm
Platter RPM = PRPM
Main Pulley Diameter = MPD in mm
Motor RPM = MRPM

Motor Pulley Diameter (MPD) = PD x PRPM / MRPM

-----------------------------------------------------------------------------------
Example:

PD = 12 inch = 304.8 mm
PRPM = 33.33
MRPM = 300
MPD = (304.8 * 33.33)/300
= 33.86328 mm
= 1.3332 inch
-----------------------------------------------------------------------------------
While using the first formula, I am getting another value (32.97438 mm). Can someone tell me which formula is more correct. The first one or the above one. In the first one, the belt thickness is also getting into consideration. Do we need to take that value also into account ?

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Bins.
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