Resistance control mechanism in an oscillator

Discussion in 'The Projects Forum' started by keyser, Dec 16, 2009.

  1. keyser

    Thread Starter New Member

    Dec 16, 2009
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    0
    I am doing a project on design of a quadrature oscillator and have been give a problem of assuming
    one of the resistance value to be variable(due to environmental factors) and to make a
    automatic controller for that resistance ... one of the things i have thought about is using a digital potentiometer
    but i am having trouble visualizing it in a practical circuit ... any insight on how to use digital pot as a
    resistance controller or any other ingenious ideas regarding automatic resistance control would be
    greatly appreciated ....

    Thanks
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Using a DPOT requires a microprocessor or some logic to change the setting. That may exceed the scope of the project.

    Google "thermistor". It is a device that changes its resistance with temperature.

    You can also look up "ldr", or "cds cell". The device changes resistance with changing light.

    You don't show the power sources - those old LM741's need +/- 15 volt supplies to operate correctly. We would probably recommend using a TL072 instead.
     
  3. keyser

    Thread Starter New Member

    Dec 16, 2009
    2
    0
    Thanks but according to the problem we have to control the changes in resistance value due to any factor (not just temperature or light) so using thermistor or ldr will not solve the problem ..
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Sorry, I thought light and temperature were affected by the environment.
     
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