Change amplitude of oscillations from phase shift oscillator

Discussion in 'General Electronics Chat' started by artmaster547, Jan 7, 2016.

  1. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    Hi
    I need some help to create a circuit that will allow me to adjust the amplitude of the oscillations from a phase shift oscillator, any help would be much appreciated
    thanks
    Art
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
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    Post a schematic showing what the oscillator is driving.

    A pot on the output into a voltage follower...
     
  3. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    it's a driving a of 1k ohms
     
  4. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    one of the problems is that I cannot add pots to the design isn't there a way to work around this i.e. using a JFet?
     
  5. dl324

    Distinguished Member

    Mar 30, 2015
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    Post a schematic.
     
  6. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    this is the current circuit
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    Don't have LTspice on my tablet. Post a screen shot.
     
  8. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    I essential want to reduce the noise present in the FFT I want to get as close as possible to there only being 1kHz present as a spike and the rest of the graph being a smooth curve
     
  9. dl324

    Distinguished Member

    Mar 30, 2015
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    So you're not asking how to vary amplitude for all frequencies?
     
  10. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    sorry I think I didn't phrase the question properly what I want is an oscillation that occurs between two limits , so oscillation between 1V and 3V
     
  11. dl324

    Distinguished Member

    Mar 30, 2015
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    That comes from having two overlapping threads.

    What is the current amplitude range?
     
  12. BR-549

    Well-Known Member

    Sep 22, 2013
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    "I essential want to reduce the noise present in the FFT I want to get as close as possible to there only being 1kHz present as a spike and the rest of the graph being a smooth curve"

    artmaster, I still don't understand what you are asking. Maybe if you told us what the circuit is for, we might grasp what you want to do.
     
  13. artmaster547

    Thread Starter Member

    Jan 6, 2016
    89
    1
    it's purely to create meets the following specifications:
    designing a sinewave generator with the following properties:
    1. power supply is nominally +9 V, but could be ±3 V, relative to a ‘ground reference’ of 0 V.

      2.output is a sine wave of frequency 1 kHz (ideally free of any harmonic content) and varies between a minimum value of +1 V and maximum value of +3 V, into an unknown resistive load as low as 1kOhm.
     
  14. BR-549

    Well-Known Member

    Sep 22, 2013
    2,004
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    Ok, are you restricted to a specific type of oscillator?

    This isn't homework, is it?

    May I ask where those specifications came from?
     
  15. crutschow

    Expert

    Mar 14, 2008
    13,050
    3,244
    The circuit you show is oscillating at abut 7Hz.
    You need to change the RC values to get 1kHz.
     
  16. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    The circuit you posted probably will saturate because all of te opamps are DC coupled. Also, what is the reason for two pulse sources in a sinewave circuit?

    ak
     
  17. BR-549

    Well-Known Member

    Sep 22, 2013
    2,004
    394
    Pardon me, are you trying to filter, C3?

    Pardon me again, I didn't read ALL the other posts on this.
     
    Last edited: Jan 7, 2016
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