XR2206 Function Generator

Discussion in 'The Projects Forum' started by MCU88, Mar 21, 2015.

  1. MCU88

    Thread Starter Member

    Mar 12, 2015
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    Hello...

    Has anyone here done a function generator project using the XR2206 chip? I did one a while back and I found it to be a toy.

    Has anyone got a better alternative to provide sine, square and triangle with the addition of variable duty cycle? Something using OPAMPs perhaps?

    [​IMG]
     
  2. R!f@@

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    Apr 2, 2009
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    Would love to have a quality function generator.
     
  3. GopherT

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    Nov 23, 2012
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    Maybe you could actually tell us what you want and/or need that the xr2206 doesn't provide.
     
  4. MCU88

    Thread Starter Member

    Mar 12, 2015
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    You'll be getting one. The XR2206 is not the solution though. The output is not true AC and cannot directly drive loads. It has no square wave. It has no variable duty cycle. The distortion is high. Very disappointed.

    Ground up OPAMP design? Schema suggestions anyone?
     
  5. MCU88

    Thread Starter Member

    Mar 12, 2015
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    • Variable Frequency 0.1Hz to 1MHz
    • Sine, Square and Triangle waves
    • Variable Duty Cycle
    • Variable Amplitude
    • Ramp Function
    • True AC or Pulsating DC Output (feature with toggle switch)
    • Digital Display For Frequency
     
  6. GopherT

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    Nov 23, 2012
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    I've never seen a function generator drive a load.

    Also, the xr2206 can output a triangle wave to sawtooth wave, the designer of the power supply you showed just didn't bother to give you those functions on the control panel. It can also do FSK modulation. Distortion can be controlled with two pins - not perfectly, but,...
     
  7. R!f@@

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    I got no ideas and I am still looking for something that can be easily built and provide pure clean sine wave in the audio range
    And may be square wave to test circuit as such.
    Variable sine wave function.
    Able to drive low Z loads
    Variable amplitude as such.

    All the things needed to test circuits from Audio to Digital.
     
  8. MCU88

    Thread Starter Member

    Mar 12, 2015
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    Square wave sorry. See post #5 too.
     
  9. bertus

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    Apr 5, 2008
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  10. GopherT

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    Here is the perfect chip. It meets everything you asked for and It can also do 0.01 Hz instead of 0.1 Hz that you asked for.
    Sine, square and triangle (that can be distorted to various ramp signals). 1 to 99% duty cycle.











    image.jpg
     
  11. MCU88

    Thread Starter Member

    Mar 12, 2015
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    The square wave output uses a separate pin. It is a dog of a chip.
     
  12. MCU88

    Thread Starter Member

    Mar 12, 2015
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  13. RichardO

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    May 4, 2013
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  14. Søren

    Senior Member

    Sep 2, 2006
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    If you can get it, the MAX038 (upgrade of ICL8038) goes to 20MHz or 30MHz and was/is pretty expensive IIRC.
    Both are seriously obsolete, but may be found at hobby electronics shops on-/offline (perhaps eBay?).

    For new designs, use Direct Digital Synthesis (DDS) instead, whether the old-skool-way or with one of the dedicated chips that's become available. You're not stuck with sine, triangle and square with DDS - any waveform you can imagine (in the bits available in a particular design) can be made.

    Whichever way you shake your electrons around, you should plan on incorporating both 50 Ohm and 600 Ohm output impedance buffers, if you want to be able to calculate anything from your measurements.
     
  15. DickCappels

    Moderator

    Aug 21, 2008
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    I suspect that the reason analog waveform generators like the MAX038 and the Exxar chips are going extinct is because the same functionality can be had my digital means. Once it is digital, it is easy to set the frequency precisely and you don't have to pass signals through potentiometers.

    The Analog Devices AD9850 is one such chip.

    www.analog.com/en/products/rf-microwave/direct-digital.../ad9850.html
     
  16. bertus

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  17. DickCappels

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    Thank you, Bertus.
     
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