Capacitor wrap cutting brief tutorial - Page 3 - diyAudio
Go Back   Home > Forums > Design & Build > Construction Tips

Construction Tips Construction techniques and tips

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th September 2014, 05:55 PM   #21
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by SonyFan View Post
As far as the black- the evidence is right in front of you.
Google "black body." This is basic physics. It's not a surface area effect.

edit: Here's a table of emissivity for your future reference- http://www.engineeringtoolbox.com/em...nts-d_447.html
__________________
The more you pay for it, the less inclined you are to doubt it.- George Smiley
  Reply With Quote
Old 4th September 2014, 06:08 PM   #22
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Originally Posted by SonyFan View Post
when Thermalright, a performance PC cooling products manufacturer, released three identical versions of their popular TRUE 120 heatsink. One came with aluminum fins and was meant to be a budget option, one came with pure copper fins, and one called the "Ultra" came with black anodized pure copper fins. Guess which one performed the best?

These objective tests are from two different hardware review sites.
http://i.imgur.com/7ac96KY.png
http://i.imgur.com/mIagrlf.png
Sorry but in this case the examples posted above are quite irrelevant.
They refer to FAN cooled heatsinks,

Click the image to open in full size.

with tons of exposed internal surface for better exchange with the air flow, and very poor external surface exposure (which would help radiation).

In this case colour isnīt important, since I guess convection takes away 100X what radiation does.
  Reply With Quote
Old 4th September 2014, 06:16 PM   #23
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
the thermal engineering is is fairly well understood - and as in most engineering questions - it depends

convective cooling is conduction to the air, less barriers the better, some power law dependency from larger delta T causing more air convective movement
forced air movement with fans usually means thermal conduction of bare metal wins out

for radiation direction of heat transfer and efficiency depend on relative temperature differences, can become larger than convection for >100 C deltas for typical electronic assemblies, but is large power of the delta T and becomes very small for lower delta T
but it can be worthwhile to have better emissivity in low airflow speed natural convection, external heatsinks seeing ~20 C room

as mentioned internal heat from current ripple with ESR should be low in most audio equipment, in fact often the biggest life shortening threat to Al Electrolytics may be from being too close to other heat sources - especially tubes

so you can't make a blanket statement - there are differences depending on internal heat generation, air temperature and flow, flow resistance, relative temperature and solid angle between radiative sources and sinks...
  Reply With Quote
Old 4th September 2014, 09:18 PM   #24
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
I work in pro audio, where the internal cosmetics are not an issue. I am sure in the audiophile area, the internal appearance of an amp is a marketing concern at the very least.

So in my experience, when I open an amp and see caps with the end exposed like that, it is almost always because the heat inside the amp - not necessarily from the cap itself, it is surrounded by heat - has cause the cap wrapper to shrink, thus exposing its own end.
  Reply With Quote
Old 4th September 2014, 10:49 PM   #25
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Well, even respected plumbers sometimes let sleeving slip somewhat and expose some of the inner works.

Click the image to open in full size.

And in hot humid days, I bet it improves cooling.
  Reply With Quote
Old 4th September 2014, 11:22 PM   #26
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
I wonder if he sells crack?
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 5th September 2014, 10:21 AM   #27
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Quote:
Originally Posted by SonyFan
As far as aluminum being a poor radiator I just don't believe it
As you live in a democracy you are of course free to believe or disbelieve anything you choose. Your belief does not affect the fact.

Quote:
we don't make heat sinks or heat sink fins out of it for no reason.
Aluminium is cheap, light in weight, a good heat conductor and easy to machine. The best heatsinks are blackened to aid radiation. Convection does not worry about colour, but may be affected by surface roughness.

Quote:
If the nude capacitors are hotter on the outside then they may in fact be cooler inside
Very unlikely, whether the heat source is inside or outside.

Quote:
I would like to see more evidence supporting the idea that something black will run cooler just for being black.
I first saw the evidence in a standard school lab experiment when I was about 14. Later I learnt the theory in my physics degree. Note that if there is an external heat source then the black body will get hotter, as it absorbs more.

So the rule is not 'black things are cooler', but 'black things are better coupled to their thermal environment'.
  Reply With Quote
Old 5th September 2014, 11:33 AM   #28
SonyFan is offline SonyFan  United States
diyAudio Member
 
SonyFan's Avatar
 
Join Date: Jul 2014
Location: Sunny South Florida
Anyone who wanted to do this and read these posts might be turned off now because they think their caps are going to catch fire and that is just not the case. That is the only point I have to make for the sake of this thread. Too much time has been spent arguing already.
__________________
"You lose, Rickles!" - Jim Lahey
  Reply With Quote
Old 5th September 2014, 11:53 AM   #29
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Quote:
Originally Posted by SonyFan
. . because they think their caps are going to catch fire . .
Perhaps just a minor exaggeration, in leiu of a coherent response?

Quote:
Too much time has been spent arguing already.
One man's argument is another man's attempt at teaching basic physics.

To sum up this thread so far:
You think they look nice.
You didn't realise that the change might affect their ripple current rating, because of thermal radiation effects.
  Reply With Quote
Old 5th September 2014, 11:54 AM   #30
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Agreed, far too many posts alleging the impossible.

Learn some facts about heat and electricity and then come back with some sensible suggestions.
__________________
regards Andrew T.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Carbon fibre vinyl wrap Assesears Full Range 3 27th January 2014 06:13 PM
Wire-Wrap vs. Solder phishead8 Equipment & Tools 12 24th May 2011 02:21 PM
Naim wrap ash_dac Everything Else 1 15th August 2006 08:35 PM
How wrap transformer... MaXiZ Power Supplies 6 13th May 2005 09:52 PM
Wrap-around veneering Gaber Multi-Way 10 2nd February 2004 08:23 PM


New To Site? Need Help?

All times are GMT. The time now is 05:05 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2