Sine, Square Wave Generator (Variable Frequency)

Discussion in 'The Projects Forum' started by indigospring, Jun 17, 2011.

  1. indigospring

    Thread Starter New Member

    Jun 17, 2011
    1
    0
    The Goal :

    To design a function generator -
    Sine, Square

    Constant output amplitude -
    For sine wave : 10Vpp (Symmetric about origin)
    For square wave : 5Vp to 0V swing

    Variable Frequency (say 1k, 2k, 5k, 10k)

    Short-listed ideas :
    1. Wein Bridge Oscillator to generate sine wave and then diode + hex inverter to obtain square
    2. XR 2206 (but output voltage is 2Vpp. Further amplification is needed). Also, MAX038 and ICL 8038 is out of production :/
    3. Timer IC circuit (this I am not aware of how to proceed)
    4. Mux capacitor/resistors to vary frequency

    Questions :
    1. Are there any other function generator ICs I can use?
    2. I hear that Timer IC 555 can be used. Can anyone link me to a VERIFIED circuit diagram?
    3. Also, in case of an Oscillator circuit, I believe Wein Bridge is best. Any alternatives?

    Thanks. Kindly reply asap
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    This PDF will give you some ideas on designing sinewave oscillators:
    sloa087_sinewave_oscillators.pdf

    The 7414 or 40106 can be used to convert the sine to squarewave.
    Do take care about the maximum input amplitude for the schmitt-triggers.

    Bertus
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The XR2206 is still being made; roughly $5.50 USD at various vendors.
    You can use an operational amplifier to increase the output voltage swing from 2v pp to 10v pp.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,048
    You could "cheat" and use an app for that, software for generating the signal. I have a nice, free function generator on my iPod. Then just build a small audio amp to boost line level up to the voltages you need. I know that's probably not what you're looking for, but your post didn't rule out cheating.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    2,536
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You may find this PDF document helpful:
    http://focus.ti.com/lit/an/slod006b/slod006b.pdf
    TI's "Opamps for Everyone" design reference.
    Have a look at section 15 which deals with sine wave generators.
    Generating a square wave from the sine wave could be as easy as using a comparator, and triggering on the zero crossing point.
     
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