Estimating Temperature by Touch

Nov 01, 2005 11 Replies

I vaguely remember an engineer mentioning an old rule of thumb for quickly estimating temperatures on circuit boards: you put your finger on a component, and it went something like this:



Feels cool ... 25 to 35 deg C Neutral ... 37 Warm ... 40 to ? Very warm ... ? Hot ... ? Makes a blister... ?



Does anybody have the numbers that go in here?



Wood



I can touch a smooth metal surface at 50C forever, 60C for about 2 seconds, and can interpolate pretty well berween.

Calibrate yourself!

John

I added some above. For most folks, 70 is about as hot as one can stand for a second or two (does depend on calluses, though).

Don't know about that but I used to know someone who used his tongue as a voltmeter for determining the voltage of batteries.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Very Hot .........."Sun of a Bitch Ar!"

Real Programmers Do things like this. http://webpages.charter.net/jamie_5

Mmm...

I have measured the "surface" temp of a 60W typical bulb and came out appox 80C with temp probe attachment for multimeter.

Cheers, Wizard

I used to do temperature testing of RF equipment in a walkin temperature chamber and changed cables at 80 deg C. Screwing and unscrewing N connectors bare-handed was a real challenge. 80 C is definitely in the hot range.

I also once had to install some electronics on an all steel crane while it was operating over a furnace. The temperature on the crane was 155 F or about 68 C.

Confirmed.

50C is now the legislated limit for hot water systems as it will not scold. 60C maybe 5 secs max. depending on your level of tolerance to pain. It is the legislated as the cut off point as well.

I pothe hethe the guyth thut torkth like thus

David

N Cook wrote:

Hi!

I can second that. My IR thermometer (at a few inches) said my 130V 60W bulbs were between 86 and 90 degrees C.

William

Yea. 113F and you will let go. Blisters at 150F.. However, my wife is a cook and most of her finger tips have been burnt over the years. She can hold 150 for several seconds. I know. She passes hot dishes to me and I drop them.

Harold

I have skin on my fingertips that's like a baby's skin...those well-known Samsung vertical IC heatsinks are hotter than I can handle.

Tom

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