Class A heat - "pull my finger" is 50 not 60 - 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 9th October 2009, 05:53 AM   #1
lgreen is offline lgreen  United States
diyAudio Member
 
lgreen's Avatar
 
Join Date: May 2003
Location: San Diego, USA
Default Class A heat - "pull my finger" is 50 not 60

I have seen a LOT of posts (or is it in the NP articles) that say for a heat sink, if you are able to hold your finger on it for a second or 2 or 3 and then pull off due to high heat/ pain, its probably about 60 degrees C, which is as hot as you want to get a heat sink given saftey considerations and the operating temp of the semiconductor, which is going to be a few degrees hotter.

Ok. Makes sense.

Today I measured a Class A amp's heat sinks. I believe that this 'finger' test gives you a heat sink at about 50C, not 60C. So good news, the devices are operating a lot cooler than I thought.

I don't think I am wussy but who knows. I used a thermocouple on a DMM and gave it time to settle in. Damn things get fric***in hot!!
__________________
Retired from DIY (2010) but still lurking now and again. My DIY audio projects- PartTimeProjects.com.
  Reply With Quote
Old 9th October 2009, 06:45 AM   #2
diyAudio Member
 
Join Date: Aug 2009
Location: San Diego, CA
After being a line cook for several years, I'm fairly certain that there's no universal "finger test" that will correlate to an actual temperature. I've seen guys take things out of a 350F oven barehanded and not blink twice and other people who can't even pick up something that barely feels luke warm to me.

I propose a less subjective test: try to cook an egg over easy on your heatsink!
  Reply With Quote
Old 9th October 2009, 06:50 AM   #3
lgreen is offline lgreen  United States
diyAudio Member
 
lgreen's Avatar
 
Join Date: May 2003
Location: San Diego, USA
Default hot or not?

Yeah I was surprised to measure this; I thought it was so hot that it would be about 65-70C but turned out to be in the 50's.

Nothing like learning by doing. Hell's Kitchen?
__________________
Retired from DIY (2010) but still lurking now and again. My DIY audio projects- PartTimeProjects.com.
  Reply With Quote
Old 9th October 2009, 07:06 AM   #4
diyAudio Member
 
Join Date: Aug 2009
Location: San Diego, CA
Maybe we should be testing our heatsinks with a steak? 60C is 140F.. which is a perfect medium rare.

I gotta stop, I'm making myself hungry here..
  Reply With Quote
Old 17th October 2009, 12:13 AM   #5
wwenze is offline wwenze  Singapore
diyAudio Member
 
Join Date: Mar 2008
Reminder: Half the conductivity = twice the temperature required to get you to "pull my finger"
  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
"Killer" Screen Driven Push-Pull Amp Initial Queries wrenchone Tubes / Valves 55 8th September 2014 12:39 AM
829B/3E29 "Triode" Push Pull Paralleled Sections coldcathode Tubes / Valves 26 28th October 2010 07:39 PM
Chip amps used in "push pull" ChrisA Chip Amps 22 2nd July 2009 10:18 PM
How Do "Heat Fins" Work In a Vacuum? DaveMcLain Tubes / Valves 7 12th April 2008 12:49 AM


New To Site? Need Help?

All times are GMT. The time now is 06:40 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