Sorry to spam the forum with my stuff, but I'm too stoked not to share the product of my winter break.
http://www.stanford.edu/~cmcgraw/zen/zen.html
Also, I'm needing to color the heatsinks of my amp black, and if I can't convince the shop at school to anodize the chassis for me, then I need a good paint. Does anyone have suggestions for a good spraypaint for aluminum? I've sprayed aluminum before, and it chipped off really easily--is this a problem with aluminum in general, or just my paint?
Chris
http://www.stanford.edu/~cmcgraw/zen/zen.html
Also, I'm needing to color the heatsinks of my amp black, and if I can't convince the shop at school to anodize the chassis for me, then I need a good paint. Does anyone have suggestions for a good spraypaint for aluminum? I've sprayed aluminum before, and it chipped off really easily--is this a problem with aluminum in general, or just my paint?
Chris
Chris,
hate to spoil your fun but all the links to the pics on ur site currently point @ ur harddisk and hence dont work exept on ur machine ... you need to make the links point at the webserver where all the pics are...
eg. everywhere in the html where the links point to somewhere in file:///C:/Documents%20and%20Settings/John%20McGraw/Desktop/c%27s%20rocks/zen/ change it 2 http://www.stanford.edu/~cmcgraw/zen/
hate to spoil your fun but all the links to the pics on ur site currently point @ ur harddisk and hence dont work exept on ur machine ... you need to make the links point at the webserver where all the pics are...
eg. everywhere in the html where the links point to somewhere in file:///C:/Documents%20and%20Settings/John%20McGraw/Desktop/c%27s%20rocks/zen/ change it 2 http://www.stanford.edu/~cmcgraw/zen/
If it's looks you're after, then paint if you can't anodize, but if it's heat transfer you want, anodize the heatsinks or leave them alone. Paint will form a thin insulating layer over the aluminum. Will the heat escape? Yes. Just not as easily. That's why you don't see 'real' heatsinks that have been painted; it's not a question of cosmetics, it's a question of thermal efficiency.
Grey
Grey
In practice I may agree with Grey's comments about painted aluminum since it's so hard to get good adhesion of the paint on the surface but data from an old National Semiconductor voltage regulator handbook suggests otherwise. One of their "Simple Rules" is to anodize, oxidize, or paint the fin surface for better radiative heat flow. They show the emissivity for various surface treatments as: black anodized aluminum as 0.7-0.9; black enamel 0.85-0.91; and black oil paint 0.92-0.96.
But Al is a pain to paint right so schmooze up the guys in the shop. Good luck.
Phil
But Al is a pain to paint right so schmooze up the guys in the shop. Good luck.
Phil
pics
Chris, would you mind sending us a jpeg or two of your Zen? Thanks. Send to PassLabs.com.. or to me,
Help@PassDIY.com
Chris, would you mind sending us a jpeg or two of your Zen? Thanks. Send to PassLabs.com.. or to me,
Help@PassDIY.com
bonehead
http://www.stanford.edu/~cmcgraw/zen/zen.html
that should work. thanks a lot, netscape composer.
thanks for the info--GRollins, I have seen a number of non-painted heatsinks, but what about radiation? Doesn't a matte-black surface emit heat better than a shiny silver one? My chassis/heatsink moves heat away from the transistor just fine, it's more that the chassis doesnt seem to give off much of that heat.
Chris
http://www.stanford.edu/~cmcgraw/zen/zen.html
that should work. thanks a lot, netscape composer.
thanks for the info--GRollins, I have seen a number of non-painted heatsinks, but what about radiation? Doesn't a matte-black surface emit heat better than a shiny silver one? My chassis/heatsink moves heat away from the transistor just fine, it's more that the chassis doesnt seem to give off much of that heat.
Chris
Chris,
Yeah, black is better, unquestionably. Basic blackbody radiation theory. I'm just concerned about the thickness of the paint offsetting the increased efficiency. Knock it once or twice and the paint will chip off (unless that primer mentioned above is well-nigh as strong as epoxy), leaving you right back where you started.
In passing, I'll note that I was looking at heatsink manufacturer sites trying to find something worthy of using with the Aleph 2s prior to going water-cooled. One thing that I found interesting was that not one of the manufacturers (at least at that time--maybe they've put it in since) gave different specs depending on the finish of the heatsink. Raw, gold, black, whatever...same specs. Now, this surprised me as theory would suggest that there's a difference, but it may not be enough to be important in practice. I was on the phone with a guy from one of the places (don't remember which one--Avvid? Wakefield?) and brought up the black vs. raw question. He thought I was loony (okay, so he has company in that assessment...). Wasn't aware of any difference depending on finish.
Last spring someone brought up the anodizing question and another critter showed up with a link to a page about anodizing car parts. Doing it yourself, that is. Go look that one up, as it may solve all your problems at once--if your compatriots can't be talked into doing the job for you, that is.
I'm not clear on why you're worried about the chassis giving off heat, but if you're expecting the chassis to accept heat from the heatsinks, you've got to keep in mind that you've got what looks like a mechanical connection there. Heat absolutely loathes crossing physical boundaries. This isn't really going to be related to the color so much as the contact area, intimacy of contact (how smooth and tight is it?), and smearing the contact area with heat sink grease.
I know they're noisy (run them below rated voltage to make them quieter) and don't look particularly nifty, but you might consider fans.
Grey
Yeah, black is better, unquestionably. Basic blackbody radiation theory. I'm just concerned about the thickness of the paint offsetting the increased efficiency. Knock it once or twice and the paint will chip off (unless that primer mentioned above is well-nigh as strong as epoxy), leaving you right back where you started.
In passing, I'll note that I was looking at heatsink manufacturer sites trying to find something worthy of using with the Aleph 2s prior to going water-cooled. One thing that I found interesting was that not one of the manufacturers (at least at that time--maybe they've put it in since) gave different specs depending on the finish of the heatsink. Raw, gold, black, whatever...same specs. Now, this surprised me as theory would suggest that there's a difference, but it may not be enough to be important in practice. I was on the phone with a guy from one of the places (don't remember which one--Avvid? Wakefield?) and brought up the black vs. raw question. He thought I was loony (okay, so he has company in that assessment...). Wasn't aware of any difference depending on finish.
Last spring someone brought up the anodizing question and another critter showed up with a link to a page about anodizing car parts. Doing it yourself, that is. Go look that one up, as it may solve all your problems at once--if your compatriots can't be talked into doing the job for you, that is.
I'm not clear on why you're worried about the chassis giving off heat, but if you're expecting the chassis to accept heat from the heatsinks, you've got to keep in mind that you've got what looks like a mechanical connection there. Heat absolutely loathes crossing physical boundaries. This isn't really going to be related to the color so much as the contact area, intimacy of contact (how smooth and tight is it?), and smearing the contact area with heat sink grease.
I know they're noisy (run them below rated voltage to make them quieter) and don't look particularly nifty, but you might consider fans.
Grey
A comparison between the emissivity of anodized and painted surfaces (and between different colours of anodizing and paint) can be found here:
http://www.electro-optical.com/bb_rad/emissivity/matlemisivty.htm#Anodized Aluminum Samples
http://www.electro-optical.com/bb_rad/emissivity/matlemisivty.htm#Anodized Aluminum Samples
Okay...that which should have clarified...confuses. Two different samples of black anodizing with different ratings. Green higher than black. Gold equivalent to one of the black samples (the higher one, natch...).
Some paints higher than anodizing?
Stuff like that will give you ulcers.
I think I'll stick to water-cooled.
(Thanks Geoff)
Grey
Some paints higher than anodizing?
Stuff like that will give you ulcers.
I think I'll stick to water-cooled.
(Thanks Geoff)
Grey
The only paint I would recommend for heatsinks are Floquil model railway paints. They are an etching laquer with either Toluene (old stock) or xylene (new) solvent. They form a very thin opaque layer, which should be good for emissivity.
A Matt finish is prefered to gloss for greater emissivity too.
Regards
James
A Matt finish is prefered to gloss for greater emissivity too.
Regards
James
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