Class A heat - "pull my finger" is 50 not 60

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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!!
 
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!
 
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