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Old August 14th, 2005, 10:30 AM   #31
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I know I can do it and I have the tools, just really busy with another project, but If I have the time I'll do up a little design in solidworks and post a drawing and stuff like that. The gears can be replaced by wheels or small bearings of some kind with a track so long as their is some good grip between the motor and the ring that holds the glass.
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Old August 14th, 2005, 10:43 AM   #32
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I would love to see a design Keith, when you have the time.

Thanks for your input,
Wayne.
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Old August 14th, 2005, 01:36 PM   #33
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Wayne,

i am seeing the problems associated with a plastic GG CD now , the colour separation I wasn't noticing until lately. I am down with the Glass GG if you figure it out for a CD player motor. Keep me posted, pls.
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Old August 14th, 2005, 05:32 PM   #34
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Mandy,
Im still trying to get my agus box together and complete with a support. As soon as I do Ill start work on the real glass design.

If im successful ill post full details and photo's of how I accomplished it.

Wayne.
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Old August 15th, 2005, 11:08 AM   #35
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Keith,
You said that you just apply voltage to a brushless pc fan motor, right? Well, the one I have has 3 wires running from it, yellow, red and black. Do i just connect to the red and black, is the yellow one an RPM feedback wire?

Thanks
Wayne.
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Old August 15th, 2005, 12:40 PM   #36
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Wayne, your 100% correct.

Black is gnd, red is V+ (usually +12v for normal operation) and the yellow is a feedback so it can be ignored. This is the normal setup for almost every fan that I've seen
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Old August 15th, 2005, 12:42 PM   #37
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Thanks Keith,

You have been very helpful

I was wondering. The fan on my CPU right now has a speed control connected to a rotary knob that mounts to the back of the pc. I was wondering if its a good idea to buy a fan like this to controll the speed of the ground glass, as the real mini35 does?

What ya think?

Wayne.
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Old August 15th, 2005, 09:24 PM   #38
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That control knob is called a rheostat (spelling???) and is kind of like a big variable resistor. You should be able to use it without problem to control the speed of the GG so what you want to do should work without a problem.

The only think i'm not sure about is how many watts they can usually dissapate because when that GG first starts spinning the current is going to be high until it gets upto speed, so It is possible to blow the rheostat or even the coils if that initial current is just to much for the fan.

I've never tried spinning glass so the angular moment might just be to much to handle so a really "beefy" fan and rheostat is perferable.

Should probably start the motor on a very low setting with the rheostat because it will keep the voltage low and as a result lower the current so it is easier on the coils and rheo until it gets the GG spinning and then speed it up after.
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Old August 16th, 2005, 05:25 AM   #39
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Thanks again Keith!!!

On another note, what batteries would you recommend for running this fan motor? I wonder if duration will be a problem?

Wayne.
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Old August 16th, 2005, 06:05 AM   #40
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I'd probaly say its all about convience in the battery selection.

The big option I see are AA nimh high capacity batteries like people mainly use in digital still cameras. They are usually around 1.2v @ 2000mah. So if you wanted the fan rated 12v @ .4 amps you need 10 AA's and they should run continously for 4 hours at top speed.

Another option is a camcorder battery. Usually 7.2 or 8.4 volts which is plenty to spin the motor and they are usually pretty high capacity li-ions. The only problem is getting the battery mount, an old charger could be modified for the mount but beyond that will be hard to get a mount for any type of camera specific battery.

Lots of options out their but this are the easiest I think, could be wrong though
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Old August 16th, 2005, 06:17 AM   #41
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Keith,
I think sticking to the AA's NiMH batts would be best. I probably wouldn't need to supply the full 12v, so maybe 6 to 8 AA's would be fine?

The camcorder battery is a good idea, im just thinking about weight. I'll have to compare a heavy duty cam batt and the AA batteries.

Cheers,
Wayne.
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Old August 16th, 2005, 12:12 PM   #42
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2. Glass GG and rotation.

I would not recommend rotating a CD-R sized glass gg at any more than 3000rpm. 1500rpm I found to be adequate for 1/50th second on the PD150.

3. Rainbows in image.

I suspect the culprit to be the close-up lens on front of the camcorder or any home brew condenser setups, rather than the gg. Before going to the ordeal of making a glass spinning gg, try a fixed gg made from a microscope slide first. These are also handy for wax tests.

Does the colour separation occur as a parallel rainbow effect or as a radial rainbow effect - possibly also associated with radial smearing or blur most noticeable at the outer edges or corners of the image. If the separation is radial and especially if the blur is there, then the relay path, ie., close-up lens and or condenser arrangement is likely to be implicated.

A plastic gg which is opaque through its entire thickness is going to confer a halo effect around highlights or sharp light/dark edges, but we are not going to use these for serious imaging are we??
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Old August 16th, 2005, 04:17 PM   #43
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I know my colour separation is not the close up lens, because I was not using it and still saw the colour separation. I am not sure that a glass GG would fix it, but I can't figure out why I am getting it with a plastic GG. I get it when looking at a lamp shade so I can see the inside and the outside (a lower angle). This is combated with closing the iris on my camera, but it makes everything much darker.
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Old August 16th, 2005, 05:44 PM   #44
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Wayne,

8 cells would give you 9.6 volts which should be plenty. These run fine at 7v (people use the 5v to the gnd and the 12v to the power and the potential difference is 7v) So you won't have a problem even with 6 cells because that is 7.2 volts.
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Old August 16th, 2005, 06:10 PM   #45
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Would a 7.2v, 2 cell lithium polymer battery do the trick? as these come in very high capacity.

Wayne
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