Voltage Controlled Oscillator 0-5v 100Hz-3khz

Discussion in 'The Projects Forum' started by GM_Quarenten, Oct 8, 2011.

Was my question simple to understand and to the point (for future questions)

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  1. GM_Quarenten

    Thread Starter New Member

    Mar 3, 2010
    3
    0
    Hi
    i would like to build a voltage controlled oscillator
    i want the input voltage to be able to take 0-5 volts
    i want the output frequency to be between 100Hz and 3kHz
    so,
    0v = 100Hz
    1V = 600 Hz
    2v = 1200 Hz
    3v = 1800 Hz
    4v = 2400 Hz
    5v = 3000 Hz

    the output frequency could be a linear relationship or a logarithmic one i don't mind, the part above is just an example.
    my question is.
    How do i design this as simple as possible, could a 555 timer do it?, or a schmitt trigger oscillator?
    and how
    would it be possible for someone to link or give me a circuit diagram with the formulas to use to design this ? XD

    (side note.. by all means any amplitude output is fine, can be ether sine wave or triangle or square wave.)
    its the input and output design i am having trouble with.

    ultimately*
    i would like to hook the output to a 100-200mV microphone so i can listen to the output on my PC.

    circuits i have looked at but i don't understand
    1. http://en.wikipedia.org/wiki/File:VCO.jpg
    2. http://www.ee.iitm.ac.in/vlsi/courses/ec330_2009/oscillator

    cheers in advance, i would much appreciate any HELP! :D
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,432
    3,360
    Try LM566.
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,647
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    Last edited: Oct 9, 2011
  4. GM_Quarenten

    Thread Starter New Member

    Mar 3, 2010
    3
    0
    Thank you for the ideas
    i am very grateful for the help : )
    ill see if i can figure something out within the week.
     
  5. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    You could also take a look at Linear Technology - LTC6990

    NOTE: Link Fixed
     
    Last edited: Oct 11, 2011
  6. GM_Quarenten

    Thread Starter New Member

    Mar 3, 2010
    3
    0
    Hi Bertus
    sorry i dont understand what the +32P part of the formula is.
    Fmin = 1 / R2 (C + 32p )
    Fmax = Fmin + 1 / R1 (C + 32p )
    i tried reading the data sheet but failed to gain any better understanding.
    cheers
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    The +32p is the internal capacitance of the 4046.
    This 32 picoFarad will not have many influecne at the low frequencies you are using.

    Bertus
     
  8. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The datasheets of the LM324 (quad opamp) and the LM358 (dual opamp) show a simple VCO circuit:
     
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