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
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
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).
I can touch a smooth metal surface at 50C forever, 60C for about 2 seconds, and can interpolate pretty well berween.
Calibrate yourself!
John
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.
Very Hot .........."Sun of a Bitch Ar!"
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.
One can check those small 9V batteries with pretty good accuracy. It became habit forming just like jolts from the old 75 and 90 volt B batteries. What else can you legally do when a kid at home?
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
Here we go again...it wasn't a pleasant experience when I checked my old cellphone PS...10.6 V, 850 mA...I thought that the top of my head was going to come off. :-)
Tom
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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