Infrared phototransistor to infrared thermometer

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Discussion Overview

The discussion centers around the feasibility of modifying an infrared phototransistor for use in an infrared thermometer, specifically for measuring temperatures in the range of -20 to 120 °C. Participants explore the principles of infrared thermometry and the underlying mechanisms involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about modifying an infrared phototransistor for temperature measurement.
  • Another participant requests an explanation of how infrared thermometers function, indicating a need for foundational knowledge.
  • A participant describes the basic operation of infrared thermometers, noting the emission of electromagnetic radiation by objects and the role of differential amplifiers in temperature compensation.
  • Questions arise regarding what specific changes in infrared light correlate with temperature variations, with one participant suggesting frequency as a potential factor.
  • Another participant emphasizes the importance of the original poster conducting their own research to gain a deeper understanding of infrared thermometers.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding infrared thermometers, with some providing explanations and others challenging the depth of knowledge presented. There is no consensus on the specifics of how to modify the phototransistor or the precise mechanisms of temperature measurement.

Contextual Notes

Participants have not reached a resolution on the modification of the infrared phototransistor or the detailed workings of infrared thermometers. The discussion includes assumptions about the need for further research and understanding of the topic.

Moses Freeman
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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.
 
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Moses Freeman said:
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.

Welcome to the PF.

Can you explain a bit about how IR thermometers work?
 
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.
 
Moses Freeman said:
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.

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?
 
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.
 
berkeman said:
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?

Frequency?
 
Moses Freeman said:
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.

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...
 
perplexabot said:
Frequency?

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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