Frequency modulator circuit

Discussion in 'The Projects Forum' started by pratapkollu, Aug 23, 2010.

  1. pratapkollu

    Thread Starter Active Member

    Dec 13, 2006
    42
    0
    HI
    Dear Members

    I wish to design a FM circuit as follows

    1) two frequencies that I use are 1 KH and 250 Hz
    The FM circuit will have a output containing 750 Hz, 1kHz and 1.25 KHz

    2) A circuit that can extract the 750 Hz signal
    3) Another circuit extracting the 1.25 Khz signal

    Please help me out.

    Thanks and regards
    Pratap
     
  2. tom66

    Senior Member

    May 9, 2009
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  3. pratapkollu

    Thread Starter Active Member

    Dec 13, 2006
    42
    0
    hai
    Thank you for the information
    I cant see any circuit in that website
    does my IE has any problem or....?
     
  4. pratapkollu

    Thread Starter Active Member

    Dec 13, 2006
    42
    0
    can any one suggest a model circuit for example
     
  5. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    Did you get the circuit showing?

    Here's a screenshot of the circuit, anyway.
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    You'll need two oscillators - one at 1K and one at 250 Hz

    You'll need to mix the two then filter out the resulting 750H and 1.25K with audio bandpass filters.

    Shouldn't be too hard to do.

    Rough part is what frequency do you expect to modulate these frequencies with?

    Can you provide some sort of explanation as to what the circuit is designed to do when it's completed?
     
  7. pratapkollu

    Thread Starter Active Member

    Dec 13, 2006
    42
    0
    hai
    this circuit is for biomolecules detection using PHR sensor
    1 KHz is frenquency with which dc bias field is supplied
    250 Hz is used to produce ac magnetic field
    these 2 mix and as you saw in spectral analysis the o/p consists of those freq components.
    i need to extract 750 Hz and 1.25 KHz compoenent separately to analysis
     
  8. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Yes, so design bandpass filters with sharp slopes at those frequencies.
     
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