Sine wave oscillator cct needed

Discussion in 'The Projects Forum' started by Bannier, May 30, 2015.

  1. Bannier

    Thread Starter New Member

    May 30, 2015
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    Just joined AAC...absolutely amazing site!
    My speciality is repairing car audio equipment,so this project is slightly new to me.
    I am looking for a design for a pure sine wave generator with good stability & very little distortion. (No square or sawtooth waves needed).
    Specs: 20 Hz - 20khz with variable freq & gain control.
    Supply voltage: 9v - 12v.
    Using 555 IC's.
    Best regards.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    You were good to go until this line...

    For your testing of audio systems, you should get a used HP or Wavetek.

    It is hard to homebrew a pure sine-wave oscillator that is tunable over a decade of frequencies. It can be done using dual-gang variable tuning capacitor, or dual-gang variable pot, but those are hard to find. Look for Wien-Bridge circuit...
     
    Last edited: May 30, 2015
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  3. bertus

    Administrator

    Apr 5, 2008
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  4. wmodavis

    Well-Known Member

    Oct 23, 2010
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  5. ScottWang

    Moderator

    Aug 23, 2012
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    Actually you still can using the square wave to do the test for audio amplifier, and of course, the frequency no need to up to 20 Khz, 15 Khz is enough for the most application, although the range of frequency you want is the audio band, but most human is not that easy to hear the high frequency, sometimes the frequency too high for us is a noise not the harmonic sound,

    You can using NE555 to build a square wave have the frequency 20Hz ~20Khz, but why is that, because if the amplifier can be amplifying the square wave then when you using it to amplifying the sine wave, there is no problem at all, but when a amplifier passed through the sine wave tested, it may not be pass through by square wave, because the square wave amplifier need more high frequency response.

    The below was what I want to use, present not including PWM yet,and I didn't calculate the frequency, I just use it, when I need to know the frequency then I will using frequency meter to measure it..

    [​IMG]
    NE555 Clock Generator and PWM adjustable circuit.

    SQUARE WAVE OSCILLATOR KIT, 1Hz to 100Khz.

    NE555 Astable Multivibrator Frequency and Duty Cycle Calculator.
     
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  6. upand_at_them

    Active Member

    May 15, 2010
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  7. Bannier

    Thread Starter New Member

    May 30, 2015
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    Wow guys,I did not expect so many replies so soon.
    Many thanks !
     
  8. Bannier

    Thread Starter New Member

    May 30, 2015
    4
    0
    So Mike,what you're saying is that this project should be as easy as homebrewing a good ale ???
     
  9. JohnInTX

    Moderator

    Jun 26, 2012
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    I assembled one of these cheapie function gens just last night to sweep the tone controls of a guitar amplifier I'm designing. It isn't Agilent but seems to do OK for my purposes. Amazon has the kit for ~$40.
     
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  10. wayneh

    Expert

    Sep 9, 2010
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    Why not just use a free app on your smartphone? Everybody with a phone or an iPod already has a function generator in their pocket. If you need more power, run it thru an audio amp. Done.
     
  11. Bannier

    Thread Starter New Member

    May 30, 2015
    4
    0
    Hi Wayneh
    Here is South Africa,we have a large population of previously disadvantaged people who do not even have electricity in the rural areas & are not accustomed to conducting hearing tests with any high tech devices (such as cell phones). This is the reason why I am designing a reliable,low tech device.
    Best regards.
     
  12. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,535
    1,251
    Jim Williams had an app note on sinewave techniques, with a couple of digital-based designs.

    One way to get good amplitude stability and low distortion is to eliminate the continuous sweep function and build only what you need. For example, if you can do your testing with a 1-2-5 sequence of fixed sinewave oscillators and a switch, then a group of phase-shift oscillators will be stable, reliable, and cheap. But these are transistor or opamp circuits, not 555's.

    ak
     
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  13. wayneh

    Expert

    Sep 9, 2010
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    OK, got it. Thanks.
     
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