LM35 behavior

Discussion in 'General Electronics Chat' started by sureshparanjape, Dec 26, 2014.

  1. sureshparanjape

    Thread Starter Member

    Feb 10, 2012
    64
    2
    I had made one digital clock showing day,date,time and room temperature. It was my first project that occupied a place in showcase in my living room!It worked fine till this December and I noticed a bug in my program that skipped a date every passing day!I checked the sketch and well found the bug, corrected the program and put it back. But... LM35, temperature sensor started showing temperature about five degrees more than previous setting could have shown and I am certain about it- I had checked with another LM35 earlier, when it was showing two degrees more than one at hand and now it shows 7 degrees more. I guess I can adjust by adjusting the program.Questions are -Can LM35 sensing temperature shift by 5 or 7 suddenly and what can be reason? Does it meanLM35 has gone bad?
    sureshparanjape
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,392
    497
    Have you compared measurements of LM35 to a regular ambient temperature thermometer?

    Have the device that contains LM35 been moved and is now located some place where there is source of additional heat?
     
  3. sureshparanjape

    Thread Starter Member

    Feb 10, 2012
    64
    2
    Sir, I don't have another thermometer; however I have compared current temperature of our city and this clock shows about 5 degree more than earlier comparison.Did I move the device- yes, for taking out micro controller to reload corrected version of the sketch but was placed at the same location later.The behavior otherwise seems to be OK except for the addition of five degrees.I suspected dust particle at the base might have increased the voltage "drop" effect;thus causing increased temperature.I had observed a strange thing:I tried to clean the base by spirit and to my surprise temperature reading started increasing slowly just after cleaning and increased by about 10 degrees! I immediately shut of the clock and was afraid that I might have spoiled the clock by cleaning the base. However, to my relief, it is working fine!
    sureshparanjape
     
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