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Old 19th December 2007, 06:53 PM   #11
pjpoes is offline pjpoes  United States
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Though about it, but I'm kinda getting sick of the amps looking like I built them. If I had better tools at my disposal I could probably use those just fine, but without the ability do all this, it ends up coming out kinda shotty.

I hate the costs involved, but I've been very close to just buying a complete enclosure from someone like Hi-Fi 2000 or ATI and being done with it. Problem to me is shipping, the shipping prices are so high I end up spending too much on the projects. Especially on the big enclosures I want. I really like the enclosure at the bottom of this link, and it would be more than enough for my project, but will end up costing me in excess of 400 dollars, plus the company hasn't been responding to my emails.
HiFi 2000 large enclosure
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Old 19th December 2007, 07:16 PM   #12
pjpoes is offline pjpoes  United States
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I just reread an old article on heatsinks and I'm starting to Think Conrads advice was more prolific for me than I originally thought. I mean, maybe I should make sure that I have minimized thermal resistance as much as possible. I bet a different mounting scheme, a replacement of those spacers with copper, some fine polishing work, etc. might go a long way toward fixing some issues.
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Old 19th December 2007, 08:42 PM   #13
quasi is offline quasi  Australia
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Quote:
Originally posted by MikeHunt79
With those 120mm fans, you can reduce the speed of them if you find the noise too much...

If you use a mains rated fan you can use a series capacitor to slow the fan down and make it completely noiseless whilst still maintaining a reasonable amount of airflow. It takes a bit of trial and error to get the right value capacitor but the results are worth it. With a fan you also get the benefit of cooling all the components inside the case and not just the heatsinks.

Note you need to use a mains rated capacitor with a bleed resistor across it (100k 1W)

Cheers
Q
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Old 19th December 2007, 10:30 PM   #14
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Quote:
Originally posted by quasi



If you use a mains rated fan you can use a series capacitor to slow the fan down and make it completely noiseless whilst still maintaining a reasonable amount of airflow. It takes a bit of trial and error to get the right value capacitor but the results are worth it. With a fan you also get the benefit of cooling all the components inside the case and not just the heatsinks.

Note you need to use a mains rated capacitor with a bleed resistor across it (100k 1W)

Cheers
Q
I've never tried mains powered fans, but use those cheapy 120mm fans for cooling all sorts of things. They are a little easier to control as you can just use a resistor in series... I find they are inaudible below 800rpm or so.
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Old 19th December 2007, 10:45 PM   #15
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Default AAvid Thermalloy #62725

Here's a heatsink that might work:
http://www.alliedelec.com/catalog/pf.asp?FN=748.pdf

stock # 619-0079 - a 6" pc. of AAvid Thermalloy profile #62725, $22.41ea.
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Old 20th December 2007, 01:29 AM   #16
pjpoes is offline pjpoes  United States
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Thanks that one from Allied might actually work. I would prefer other options, but if I can't find something else, that might work. The biggest problem with those is that they aren't anodized, so thats an extra expense, and the one from Ebay is a little cheaper, with a similar rating, and a thicker base. Thanks again for the feedback guys.

Anyone else have thoughts on the copper idea, is it a silly waste of money. I mean, a chunk of similar aluminum is a whole lot cheaper, but if the copper is that much better, we still aren't talking a lot of money here.
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Old 20th December 2007, 01:48 AM   #17
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Being the diy forum, I'll toss out a diy idea. It's pretty easy to get aluminum extrusions at the local home/hardware outlet. It's also pretty easy to get aluminum or copper plate from various metal vendors. IMO, there's a good advantage with copper if you can afford it. You'll also need a jar of fine alumina powder from a lab supply company. It's inert, so there shouldn't be any problem buying or shipping it. Now, mix up a batch of your favorite epoxy, and load it up with alumina powder. Glue some pieces of u-channel aluminum extrusion to the plate, clamping to keep the glue joint thin. Voila! Homemade diy heatsinks. This method gives you a lot of freedom on fin placement and size.

FYI, there's a local company that manufactures heatsinks in an unusual manner. They have an aluminum plate with narrow slots. They just cut aluminum fins and press fit them in the slots. This allows them to get a much higher fin count than can be extruded. No, they won't sell small quantities, but if you had a small milling machine and a saw blade. Hmmm... wonder if the technique could be done with a carbide blade on a table saw. I've never cut aluminum on the table saw, but many say it can be done.

Finally, here's a truly crazy diy idea, and you can use it for air or water cooling. Get a copper plate and clean it. For water cooling, set up a pattern of small diameter copper refrigeration tubing, and just solder it to the surface. For air cooling, use a set of parallel copper tubes of say 1/2" diameter, and maybe use a couple few layers. Solder the whole mess together, one layer at a time. You'll need a big torch head, but propane will likely still be sufficient. I think the small tube idea can also be used for a heat pipe system. They use a wick of some sort to transfer the liquid to the hot side, where it vaporizes and heads back to the cool side. I believe methanol is used. Google fancy microprocessor coolers.

IMO, any project worth it's name has to involve oxy-acetylene, burns, sheet metal cuts, and the use of a large hammer
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Old 20th December 2007, 02:02 AM   #18
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I've never cut aluminum on the table saw, but many say it can be done.

Yes you can, and it just occurred to me that I DO have a use for that crappy pihrana saw blade I was given


7/10
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Old 20th December 2007, 02:35 AM   #19
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Quote:
Originally posted by quasi
If you use a mains rated fan
Cheapo rpm controller from Oz : here
__________________
BOXES for crying out loud
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Old 20th December 2007, 03:14 AM   #20
Minion is offline Minion  Canada
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Has anyone ever tried useing a Peltier to cool down a transistor,Chip, Heatsink...

http://en.wikipedia.org/wiki/Peltier-Seebeck_effect


Sounds like it might be a neat solution...??!
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