rc phase shift oscillator

Discussion in 'General Electronics Chat' started by vibhordabas, Mar 31, 2014.

  1. vibhordabas

    Thread Starter New Member

    Mar 29, 2014
    2
    0
    this is the output after 2 RC stages designed to give 55° phase difference.but further adding of more stages does not effect the output phase(yellow).the output is already 180° out of phase as it is the output of an Common emitter amplifier.i want to add 180° more phase with 3 RC stages.but no phase addition takes place after adding 3rd RC stage.what might be the potential problem?

    first image is of output from transistor

    http://postimg.org/image/ikm2n0uab/

    second image is after two RC stages

    http://postimg.org/image/u5lv9ienz/
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,546
    1,252
    Please post the schematic. The details matter.

    ak
     
  3. w2aew

    Member

    Jan 3, 2012
    219
    64
    Oscillation will occur at whatever frequency results in positive feedback. Adding more delay in the loop will only reduce the operating frequency, not add more phase shift at the same oscillation frequency.
     
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