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Topic: Sidewinder -- double MUT

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-19-2007 09:03 AM

VFDs have gotten much less expensive over the years (though some have gone up). If you go with three phase motors...the bulk of the price will be in the motors. You just need to set the parameters to fit your needs.

Steve

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-19-2007 09:16 AM

quote: Michael Moore
The best option for these kinds of tools are VFD drive circuits with 3 phase motors

The other problem is that at least with BAldor the smallest they make is 1/4 hp... and that motor is fairly large. You can see the Baldor motor and controler here. Same one we use on the DP-70. Cost for motor is about 200.00 cost for single phase to three phase vfd inverter is about 400.00. There are cheaper bit no less smaller options from reliance... I just hate their cheap line of VFD's though...not user friendly at all!

Mark

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Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 07-19-2007 10:54 AM

quote:
The other problem is that at least with BAldor the smallest they make is 1/4 hp... and that motor is fairly large. You can see the Baldor motor and controler here. Same one we use on the DP-70. Cost for motor is about 200.00 cost for single phase to three phase vfd inverter is about 400.00. There are cheaper bit no less smaller options from reliance... I just hate their cheap line of VFD's though...not user friendly at all!

I think this is good, but is large and heavy....all fabric made stuff like this have DC motors anf about 300W power at whole unit...

And construction get's heavy with this...this is very important since I prefer to get less heavy so it can be used as portable!

But....somebody mentioned that Eprad Double MUT works fine...and it use some primitive regulation with transformer...so this with DC motor and PWM regulator gonna work as well good and better, since there can be trimmer potentiometer in serial with main dancing arm potentiometer to get good regulation area, and another potentiometer for projectionist to get manual control when film is building up or down!

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Tim Reed
Better Projection Pays

Posts: 5246
From: Northampton, PA
Registered: Sep 1999

posted 07-19-2007 12:51 PM

MEZ MOHELNICE, s.p.

Just curious... what does "s.p." mean? I see that a lot with world companies.

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Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 07-19-2007 01:27 PM

Marin

The PWM you have a link for is for small RC like DC motors that will run on 12 to 24 volts. Not enough torque for you application. get motors like this: DC motor
Then get conrollers like this: motor controller
Not too expensive and they work very well.

Mike

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Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 07-19-2007 06:45 PM

I prefer use 24V motors, and I got feedback from people who did this that this motors work good (even 12V).

But I don't think torque will be problems with this motor and transmission to rell 5:1, motor about 2000rpm..rell max 400rpm.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-19-2007 09:19 PM

Marin,
Sounds like a good choice for motors. You can still build it like the EPRAD including the autofomrers but you just have to have to calculate the correct AC voltage to feed into the variable transfomrers for the 24 volt motors.

Mark

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Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 07-19-2007 11:10 PM

Ah ok I see what you are doing, I can see using 12 or 24 V motors. Do those PWM controllers take a DC line in or an AC line? if they take DC so you could just build a small power variable power supply and you could adjust for voltage in. Also i think it would be a good idea to have a pot that can override the dancer pot for the projectionist to increase take up if there were a problem with take up timing.

Mike

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Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 07-20-2007 04:28 AM

quote: Michael Moore
Do those PWM controllers take a DC line in or an AC line? if they take DC so you could just build a small power variable power supply and you could adjust for voltage in. Also i think it would be a good idea to have a pot that can override the dancer pot for the projectionist to increase take up if there were a problem with take up timing.

Yes, I also gonna put that potentiometer for manual take up.
I decided to go with PWM because is better for moment and starting torque for motor, and off course is producing less heat than normal regulator. Simple PWM with SG3525 and MOSFET transistor taking DC from external power supply!

I was thinking about PWM like this.

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Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 07-20-2007 08:08 AM

that's a perfect little project to get as a kit and put together. I think that will work great for what you propose.

Good Luck

Mike

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-20-2007 08:22 AM

Its going to take a really big Q-1 or multiple in parallel to hold up under driving large reels. Also be sure to match the multiple Q-1's so each shares the currenbt equally!! If you don't you may experience failures of the drvice thats handling the majority of the current. Matching them is VERY easy to do. Also with this setup there is a dangerous prospect of the drvice shorting and the large real all of a sudden going full tilt! That used to happen on the RCA FR-35's.

Mark

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-20-2007 09:28 AM

Personally, I like Michael's choice in DC Motors. With a 6750 RPM potential...one could turn around Titanic in under 15 minutes [Wink]

For me, at least...I've not had the best of experiences with Minaric controllers on DC motors...a little too unstable for me and too many failures.

Steve

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-20-2007 09:54 AM

There is no doubt in my mind that a gear reduction motor is going to work the best for this purpose. Thats been proven in many applications just like this that already exist. Also the PWM chip used in the drawing in the above link is interesting as one can also add an error amplifier to it. In other words you could regulate the pay out/take up speed by counting perfs with an opto pair and comparing them to a refrence frequency. The tourque of the motor would adjust relative to the refrence to keep that payout/take up speed linear regardless of the diameter of film thats wound on the reel. This could also easily be applied to a platter..... might be somewhat along the lines of what Kinoton does..... although I'd bet they complicated it with an mpu. Am only familiar with the old Phillips platters. I am pretty sure that Big Sky is doing something along these lines.

Mark

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Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 07-20-2007 12:59 PM

quote:
I've not had the best of experiences with Minaric controllers on DC motors.

I agree with this, however they work well but not always reliable, however there are other options like:
nice conroller
and
not the best but could work
you could ever put this in too
break

I can see using the smaller PWM and I think it should work I would rather haver a little over kill then under kill.

by the way when I use the quote button how do I give credit for the original poster?
Mike

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-20-2007 01:30 PM

AC-Tech and Lenze seem to have come up with some really nicely featured, low cost drives

AC-Tech/Lenze

I've used them and they are spot-on for frequency (not as guaranteed as you would think in some VFDs).

Steve

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