Can we make heatsinking easy? - Page 4 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 27th March 2012, 06:03 PM   #31
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
Quote:
Originally Posted by AndrewT View Post
10*30*100mm is 0.03litres
The volume is immaterial.

It is the surface area that dissipates the heat.

Volume only comes into play with MASSIVE heatsinks that are trying to dissipate heat over a large area.
  Reply With Quote
Old 27th March 2012, 11:50 PM   #32
diyAudio Member
 
Join Date: Mar 2007
Location: California
If you navigate your browser on over to Heat Sink USA and select a profile, it says RIGHT AT THE TOP OF THE PAGE the heat transfer per length of heatsink (or per length specified if not 1").

It doesn't get simpler that that.

-Charlie
  Reply With Quote
Old 28th March 2012, 08:09 PM   #33
hpp3 is offline hpp3  United States
diyAudio Member
 
hpp3's Avatar
 
Join Date: Feb 2012
Quote:
10*30*100mm is 0.03litres
Typo. Sorry.
I was referencing Marra's post about the chunk of aluminum 10x80x300mm. If I recall correctly, I mentioned that I was tired. Thanks for the correction.

Quote:
The volume is largely immaterial.
It is the surface area that dissipates the heat.
Hmm, really? So I could cut and bend up some old sheet aluminum I have lying around, and it would work? Sweet.
Although I could see problems with that being dimensionally unstable (warps, etc causing surface contact voids) and so probably more prudent to use properly machined aluminum stock.

Quote:
If you navigate your browser on over to Heat Sink USA and select a profile, it says RIGHT AT THE TOP OF THE PAGE the heat transfer per length of heatsink (or per length specified if not 1").
Sure, except I was having quite the trouble figuring the math for individual chipamps to arrive at that magical number. What would be EVEN COOLER is if they also provided a list of "Recommended to work with..." devices (which was kinda the point of my OP), but I'm sure that list would be prohibitively large and quickly out-of-date, so scratch that idea, I'll just do the bleeping math. *grumble*

Thanks all, i know SO much more about heatsinking than I did when I started.
Really, I mean that.

Last edited by hpp3; 28th March 2012 at 08:14 PM.
  Reply With Quote
Old 28th March 2012, 08:17 PM   #34
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Quote:
Originally Posted by hpp3 View Post
Typo. Sorry.
I was referencing Marra's post about the chunk of aluminum 10x80x300mm. If I recall correctly, I mentioned that I was tired. Thanks for the correction.

Hmm, really? So I could cut and bend up some old sheet aluminum I have lying around, and it would work? Sweet.
Although I could see problems with that being dimensionally unstable (warps, etc causing surface contact voids) and so probably more prudent to use properly machined aluminum stock.

Sure, except I was having quite the trouble figuring the math for individual chipamps to arrive at that magical number. What would be EVEN COOLER is if they also provided a list of "Recommended to work with..." devices (which was kinda the point of my OP), but I'm sure that list would be prohibitively large and quickly out-of-date, so scratch that idea, I'll just do the bleeping math. *grumble*

Thanks all, i know SO much more about heatsinking than I did when I started.
Really, I mean that.
If volume is sufficient, surface area is what determines the heat loss to air. If you have a lot of surface area but the fins are too thin, the internal conductive resistance will be too high and much of your surface area will go to waste, lowering your effectiveness.
  Reply With Quote
Old 29th March 2012, 12:28 AM   #35
hpp3 is offline hpp3  United States
diyAudio Member
 
hpp3's Avatar
 
Join Date: Feb 2012
Quote:
If you have a lot of surface area but the fins are too thin, the internal conductive resistance will be too high...
Aha, I just KNEW there had to be some logic to why we all didn't just use some zig-zagged sheet metal for heat sinks, here it is, and I'm left with my head in my hands wondering why I just didn't pick up on it.
Thank you, Sir.
  Reply With Quote
Old 29th March 2012, 12:51 AM   #36
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
some commercial products DO use zigzagged sheet metal crimped to a piece of L-angle as a heatsink. It is usually quite inferior to a real aluminium extrusion.

For the chipamps you mention it will probably be adequate, however by the time you have manufactured this yourself (unless you have the tools and materials to hand for little/no cost), you can buy a sensible extrusion already.

For your reference, A 2xLM3886 amp I built uses a 160mm wide, 25mm deep, 70mm high non-anodised extrusion I got from eBay, with 25v supplies. It gets warm when driving a 4 ohm load at decent volume, but not excessively so.
  Reply With Quote
Old 29th March 2012, 02:15 AM   #37
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Quote:
If you have a lot of surface area but the fins are too thin, the internal conductive resistance will be too high...
I see that as a simple redundancy, so of course it's true.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 29th March 2012, 02:36 AM   #38
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
I use rough approximate formua, it works for me. Resistance in Celsius degrees per watt equels 50 divided by square root from area in square centimeters.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 29th March 2012, 08:49 AM   #39
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
That sqrt & 50 sounds familiar.
What does ESP say on the subject?
__________________
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
how easy to make tube amp? space2000 Tubes / Valves 4 28th June 2008 11:24 PM
Easy PSU question - help me make this 12v DC power supply better. owdi Power Supplies 8 2nd May 2007 04:42 PM
Class A heatsinking, or heatsinking in general! NUTTTR Solid State 27 22nd January 2005 01:48 PM
DIY Turntable Concept (Easy-to-make) comabereni Analogue Source 10 10th November 2004 10:30 PM


New To Site? Need Help?

All times are GMT. The time now is 01:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2