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Estimating Temperature by Touch

Discussion in 'Electronic Repair' started by Woody Brison, Nov 1, 2005.

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  1. Woody Brison

    Woody Brison Guest

    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?

  2. N Cook

    N Cook Guest

    Don't know about that but I used to know someone who used his tongue as a
    voltmeter for determining the voltage of batteries.
  3. 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).
  4. John  Larkin

    John Larkin Guest

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

    Calibrate yourself!

  5. Jason D.

    Jason D. Guest


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

    Cheers, Wizard
  6. jgreimer

    jgreimer Guest

    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

    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.
  7. Jamie

    Jamie Guest

    Very Hot .........."Sun of a Bitch Ar!"
  8. Terry Smith

    Terry Smith Guest


    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.
  9. 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
  10. quietguy

    quietguy Guest

    I pothe hethe the guyth thut torkth like thus

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

  12. Harold Ryan

    Harold Ryan Guest

    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

  13. Here we go 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. :)

  14. 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.

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