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will this really give me a triangular wave?

Discussion in 'General Electronics Discussion' started by AFex54, Aug 14, 2015.

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  1. AFex54

    AFex54

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    Apr 10, 2015
    its essentially just a low pass filter, so I feel like im always going to end up a with more of a curvy ramped wave on the output.
    Is this the case?
    perhaps I need to find the triangular sweet spot by adjusting the value of C2 and R5?

    [​IMG]
    Also the device that produces the square wave also has a ramp wave, maybe this is better route for conversion to triangle?
     
    Last edited: Aug 14, 2015
  2. Miguel Lopez

    Miguel Lopez

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    Jan 25, 2012
    It is a real triangular wave and of course it has some distortion. Nothing is 100% pure in the real world.
     
  3. Alec_t

    Alec_t

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    Jul 7, 2015
    The 741 is a poor choice because of its limited output swing, bandwidth and slew rate. For a fixed input frequency square-wave, R4 and C2 determine the slope of the triangle wave and hence the peak-to-peak amplitude (up to the point where clipping occurs because of the poor performance of the 741).
     
  4. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Turning a ramp or sawtooth wave into a symmetrical triangle wave is much more difficult.

    ak
     
    AFex54 likes this.
  5. AFex54

    AFex54

    144
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    Apr 10, 2015
    I realise there will be distortion but Im talking about an isoceles triangle , my synth already has a ramped wave (which is techincally also triangular) so if this converter is too ramped I dont see the point in using it.
    for example this amount of distortion would be more than perfect:[​IMG]
    I hadnt even noticed the Op Amp they used, I will be using a TL074.
    My square wave is not fixed though, will these kind of converters only be suitable for fixed frequency waves ?
     
    Last edited: Aug 14, 2015
  6. AnalogKid

    AnalogKid

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    Jun 10, 2015
    For a constant amplitude input squarewave, as its frequency increases the output triangle wave amplitude will decrease. This is because the integrator is a constant slew rate circuit.

    you don't say what the value of R5 is, but the larger it is, the straighter the triangle sides will be.

    ak
     
    AFex54 likes this.
  7. AFex54

    AFex54

    144
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    Apr 10, 2015
    any idea how significant the decrease would be?
    my synth is LoFi to begin with so if its only slight then I doubt it would pose too much of an issue.
     
  8. Alec_t

    Alec_t

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    803
    Jul 7, 2015
    Do you have to use a converter to get from a square wave to a triangle wave? If not, a simple CMOS inverter Schmitt trigger oscillator will produce an output similar to that in post # 5, as well as a square wave of the same frequency (but not the same amplitude). The 'triangle' output amplitude would be fixed and independent of the oscillator frequency (unlike the post #1 circuit).
     
    AFex54 likes this.
  9. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Inversely proportional - twice the frequency, half the amplitude.

    ak
     
    AFex54 likes this.
  10. AFex54

    AFex54

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    Apr 10, 2015
    unfortunately yes
    thanks that was really helpful
     
  11. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Ask a decent question, get a decent answer.

    ak
     
    Arouse1973 and AFex54 like this.
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