Sine Wave from LM324?

Discussion in 'General Electronics Chat' started by RogerTango, Apr 22, 2011.

  1. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    I have the desire to generate a 600hz audio tone using an LM324 quad op-amp I have on hand, it would be powered by +5/Gnd.

    Does anyone have a schematic for this specific op-amp?

    Thanks in advance for any help,
    Andrew
     
  2. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    I should mention, the simplest diagram would be desired.

    Optionally, I can generate the desired tone with a 555 timer, but it is square wave. I have tried to convert it to a "sine wave" using 2 intergrators in series, but the best I could do is convert it to a sawtooth with the first integrator.

    Additional help with the second would be appreciated.

    Andrew
     
  3. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    I am viewing the audio wave form with a DSO Nano BTW.
     
  4. nigelwright7557

    Senior Member

    May 10, 2008
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    Look up phase shift oscilator.
     
  5. rogs

    Active Member

    Aug 28, 2009
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    This post: http://forum.allaboutcircuits.com/showpost.php?p=220880&postcount=45 from a thread about making a 600Hz oscillator has a circuit that you should be able to use. Just try an LM324 instead of a TLO7*
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    A lousy old LM324 quad opamp has lots of hiss and has crossover distortion.
    If you need a good inexpensive quad opamp then use a TL074. A dual is a TL072 and a single is a TL071. But their minimum supply is 7V. Use a 9V battery.
     
  7. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    I ordered some TL074 chips to play with also, thanks for the suggestion.

    What about wave shaping with the op-amp I mentioned? Can I make a sine out of a square? Suggestions please, what I tried only presented a sawtooth.

    Thanks for the help!
    Andrew
     
  8. Audioguru

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    Dec 20, 2007
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    "The opamp I mentioned" doesn't say which opamp.
    If it is a lousy old LM324 or LM358 then it is too slow, has lots of hiss and lots of crossover distortion. Audio opamps should be used.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    I can tell we are going to be friends. I still have my C128 set up with a CMD 4Gig HD, SuperCPU, and a full selection of drives setup (a C= knows what I mean).

    I am one of the guys who knows 555 really well around here. There was another thread that used a 555 to make something pretty close to a sine wave, but if you're willing to go with op amps TI has a pretty good publication on just this subject.

    Bill's Index

    Sine Wave Oscillators A PDF abstract by TI

    You didn't say what frequency you were going for, it matters for whatever op amp you are using.

    I favor the Bubba Oscillator myself, silly name, but easy to build using a quad op amp.

    You a member of C= Homestead?
     
  10. Jaguarjoe

    Active Member

    Apr 7, 2010
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  11. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    600Hz, Bill.:)
     
  12. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    Thanks for the help guys, I am currently looking at Forrest Mims's function generator circuit... however instead of using the first OPAMP to generate the square wave, I will try using the 555's SW output and feed it through the stages of OPAMPs to refine it to a sine wave, Id "like" to be able to have variable pitch, somewhere between 400hz and 800hz. This is going to be a side tone generator for a morse code keyer project Im working on (strictly hobby).

    Bill, I liked the old C64 that I learned ASM on, so I figured it would be a neat avatar. I no longer have that 'puter, but I spent a lot of hours at the keyboard of it (Yeah, I was that popular).

    Ill post back with any progress/failures.

    Thanks,
    Andrew
     
  13. tom66

    Senior Member

    May 9, 2009
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    You can't turn a sqaure into a sine easily.

    HOWEVER, you can turn a triangle wave into a sine wave with a reasonable distortion level - about 1-2%.

    [​IMG]http://falstad.com/circuit/e-sinediode.html

    And you can turn a square into a triangle by integrating it, but the amplitude will vary with frequency.
     
  14. Audioguru

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    Dec 20, 2007
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    When you filter a square-wave into a sine-wave then the filter parts must be changed when the frequency is changed. Without changing the filters then low frequencies will not be filtered enough or high frequencies will have their amplitude reduced.
     
  15. Ron H

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  16. Audioguru

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    Dec 20, 2007
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    Digikey and Newark do not have any ICL8038 ICs so I guess it is not made any more. I used it 29 years ago.

    Digikey doesn't have any XR2206 ICs but Newark has only a few hundred so maybe it is also not made anymore.

    The MAXIM one is not made anymore because the manufacturing place was destroyed.
     
  17. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    Were reading each other's minds! I was just thinking of a function generator chip instead, would simplify my project, adding a little more to cost but still reasonable cost.

    A few places have the XR2206
    http://octopart.com/parts/search?q=XR2206

    If I can have variable frequency sine wave that would be a bonus, looks like the FG chip may be the 'only' simple option.

    Andrew
     
  18. Ron H

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    Apr 14, 2005
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  19. Jaguarjoe

    Active Member

    Apr 7, 2010
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    Use the formula presented in the article and it can be almost any frequency one desires, certainly 600Hz.
     
  20. RogerTango

    Thread Starter New Member

    Apr 22, 2011
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    Which, article? Ive lost track....
     
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