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Interface NTC thermistor with microprocessor

  1. Jan 7, 2015 #1
    1. The problem statement, all variables and given/known data
    A microcontroller for temperature limit control has a 0 V to 5 V
    power supply. An NTC temperature sensor provides an input voltage
    to a ・} 5 V comparator op-amp. Depending upon whether the
    temperature is below or above the set limit, the output from the opamp
    comparator will be low or high. It is undesirable for a direct
    electrical connection to exist between the sensor and the controller.
    Draw a circuit diagram to show how you could interface the NTC
    sensor to the microcontroller. Resistor values are not required.

    2. Relevant equations

    3. The attempt at a solution
    I have a diagram of a window comparator circuit (see attached) with the thermistors output being one of the opamp inputs. I think I could use a optics to transfer the signal from the comparator to the microprocessor. I was thinking of a LED to transmit the signal and a photodiode to receive it at the microprocessor, but I'm unsure how to draw this. Any help would be greatly appreciated. Window Comparator.gif
  2. jcsd
  3. Jan 7, 2015 #2


    User Avatar

    Staff: Mentor

    Do a web search on "optocouplers". You may get some ideas.
  4. Jan 8, 2015 #3
    Yeah thanks I got some help from my buddy, just wanted to make sure I was drawing the components correctly. Never been great with electrical circuits.
    Thanks for the reply.
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