Measuring temperature with TO-92 package

Discussion in 'General Electronics Chat' started by Razor Concepts, Apr 28, 2010.

  1. Razor Concepts

    Thread Starter Senior Member

    Oct 7, 2008
    Many temperature sensors are available in the standard transistor TO-92 package. Are these designed only to measure air temperature? Say I had a sheet of metal, would I just use some heatsink compound to mount the sensor, and it will measure the temperature of the metal accurately?
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Of course. They are made to output the ambient temperature. Attaching the package to a surface will make it respond to that temperature. For better accuracy, place some foam over the LM34(35) to isolate it from the air.

    With good insulation on the leads, they work fine in liquids, too.

    Nothing beats a really weenie thermistor for fast response, but you have to linearize the output.
  3. SgtWookie


    Jul 17, 2007
    If you want the sensor to stay permanently attached, use a bit of J-B Weld (the regular, not the 5-minute stuff) and glue the flat face to the surface of your material.

    For the insulation, consider using this stuff:
    It's low expansion, so it won't try to rip the leads off your temp sensor. It's flexible when it cures. Don't use the high expansion foam.