Triangle wave generator?

Discussion in 'The Projects Forum' started by GiovaGiov, Apr 3, 2015.

  1. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Hi,

    I was wondering how to achieve the following triangle waveform:

    [1]
    [​IMG]
    I've seen some circuits based on the infamous NE555 (like the following: http://hades.mech.northwestern.edu/index.php/Circuit_diagram_for_wave_generator)

    But this circuit based on NE555 is only able to give me a triangle waveform which starts (powered at 15 V) from 5 volt to 10 volt.

    There is some other IC (maybe a function generator like ICL8038 or CD4049, or again some Opamps) which is able to generate a triangle waveform as shown in the picture [1] ?, Someone could suggest me some practical schematic?

    Thank you.
     
  2. #12

    Expert

    Nov 30, 2010
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  3. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Hi, thank you for the reply.
    I've seen most of these circuits, and most of them aren't able to cover my needs; I would prefer to receive some suggestion from someone which has built some similar circuit and which is surely functional :)

    Thank you anyway.
     
  4. #12

    Expert

    Nov 30, 2010
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    You have not stated your needs except for, "adjustable frequency triangle wave". How am I supposed to guess which of hundreds of options will provide for your needs?
     
  5. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Take the 555 oscillator with a rail-to-rail output op-amp and amplify it 3 times.

    Bertus
     
  6. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    I'm sorry, maybe there is a lack of comprehension, since English is not my main language. My mainly needs is to find a schematic that would me assure an excursion of the triangle wave between 0 and 15 volt, and would be nice if I can adjust this waveform between 200 and 1200 hz.

    Thank you.
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I can't think of any circuit which would ramp from 0V to 15V if the supply were only 15V, so I'm guessing the waveform shown involved an opamp with a dual voltage supply, with +V >15V and -V < 0V.
     
  8. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Thank you. Do you have some example? Anyway I have done some experiments using an NE555, but the resulting waveform wasn't exactly as i need:
    http://s12.postimg.org/9cf2bc0n1/Onda_Trigger.jpg
     
  9. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The wave form you show is not exactly linear.
    The wave form of the 555 is also not linear.

    Bertus
     
  10. #12

    Expert

    Nov 30, 2010
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    Have you just shown us what you really need? That is not a triangle wave.
     
  11. GiovaGiov

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    Apr 3, 2015
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  12. bertus

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    Apr 5, 2008
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    Hello,

    Have a look at the following page:
    http://www.maximintegrated.com/en/app-notes/index.mvp/id/4362

    In the schematic the reference is 1.23 volts, wich is about 1/4 of the 5 Volt powersupply.
    This will give the asymetric wave form.
    If you want a symetric waveform the reference voltage needs to be 1/2 of the powersupply.

    Bertus
     
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  13. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Thank you Bertus, this schematic looks very interesting.
     
  14. MikeML

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    Oct 2, 2009
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    Try this:

    46.gif
     
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  15. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Hi MikeML, this would be very good! Can you suggest me which kind of opamp could I use for this circuit?
    Thank you very much.
     
  16. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    I was afraid you would say that. ;)
    Here are three in DIP package that DigiKey has in stock. Learn to use their (or Mouser's) search tool if you dont like those....
     
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  17. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Thank you, I really appreciate your suggestion and advices!
     
  18. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    @MikeML : can you send me the .asc file?
    Thank you.
     
  19. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Since I see the LT1498 in the DigiKey list, so I repeated the sim with that part. Note I can increase the gain of the buffer amp a bit, and get pretty close to the rails.
    46a.gif
     
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  20. GiovaGiov

    Thread Starter Member

    Apr 3, 2015
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    Ok, I replicated the schematic using the LT1498, so i think that i will go with your schematic :)

    Thank you again for your precious help!
     
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