Infrared phototransistor to infrared thermometer

  1. I am designing a tyre temp monitoring system for my Final year project and I would like to know if it is possible to somehow modify a infrared phototransistor to be able to measure an objects temperature in a range of -20 - 120 C.

    Any suggestions would be greatly appreciated.
  2. jcsd
  3. berkeman

    Staff: Mentor

    Welcome to the PF.

    Can you explain a bit about how IR thermometers work?
  4. I have a basic knowledge of how they work:

    Objects with temperatures above zero kelvin emit electromagnetic radiation in the form of waves, the radiation between 0.7umm and 20umm is collected by the lens of the thermometer which is then focused onto the sensor. The output is an electrical signal which is then worked out to find the temperature.

    I am not too sure about the internal circuitry but I believe they use a few differential amplifiers for the temperature compensation.
  5. berkeman

    Staff: Mentor

    As the temperature of the object changes, what changes about the IR light coming off of it that is used to figure out the temperature?
  6. I believe the change in energy is converted to an electrical signal that is displayed in units of temperature after being compensated for ambient temperature variation.
  7. Frequency?
  8. berkeman

    Staff: Mentor

    That's not very specific, nor very accurate. What reading and research have you done so far on the subject? This is *your* project after all, so you should be doing the reading to gain a basic understanding of how these things work.

    Please do some reading at wikipedia and/or HowStuffWorks, and then tell us in better detail what the mechanism is behind IR thermometers...
  9. berkeman

    Staff: Mentor

    In case you hadn't noticed, I'm trying to get the OP to actually do some work here. Please let him do some research and get back to us. Thanks :smile:
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