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Crystal Oscillator - synchronized two crystals

Discussion in 'Electronic Design' started by [email protected], Feb 20, 2007.

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  1. Guest

    Is there a way to synchronize two crystals for two different crystal
    oscillator circuits. Driving the two crystal inputs does not work, the
    circuit draws too much current.
  2. Lefty

    Lefty Guest

    Possibly a small value capacitor between the two tank circuts ?
  3. Guest

    That is, driving the two crystal inputs with another oscillator
    circuit does not work...
  4. Guest

    The only circuitry visible is the crystal, the oscillator circuit is
    internal to the part.
  5. John Larkin

    John Larkin Guest

    Yes, but not for a person who calls himself "nicefarts."

  6. Gareth

    Gareth Guest

    You could use a PLL and a voltage controlled crystal oscillator.

    Is there a good reason why you can't just use one oscillator?

  7. Guest

    There are two units, both with their own oscillators build in. The
    only parts exposed are the crystals. I want to sync the two crystals
    (which would then sync the oscillators), or the just two oscillators
    with a faked crystal.
  8. It sure reads like he doesn't understand how to do that, hence
    his perceiving that he needs a far more complicated method, ie
    synchronizing to oscillators.

    It sounds more like a drive problem, or maybe he's trying to
    feed an external oscillator into the wrong crystal pin, so instead
    of connecting to the input of the gate that's being used as
    an oscillator in the IC, he's connecting to the output of that gate,
    which likely would cause drive problems.

  9. Most any crystal's response can be overridden by a strong enough
    external circuit.

    The request makes zero sense whatsoever.

    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: email:

    Please visit my GURU's LAIR web site at
  10. Tim Wescott

    Tim Wescott Guest

    Perhaps if you shared the IC part numbers, someone motivated could look
    at the data sheets?

    Normally with parts like this there's an amplifier built in to the chip,
    and it's as easy as pie to drive the input side. Something is odd about
    your setup, and you're not giving us enough information to figure out what.


    Tim Wescott
    Wescott Design Services

    Posting from Google? See

    "Applied Control Theory for Embedded Systems" came out in April.
    See details at
  11. Rich Grise

    Rich Grise Guest

    Then take a 100 pF capacitor, solder a wire to each lead, and touch
    one cap lead to one pin of one crystal, and the other lead to one
    pin of the other crystal. Try 1-1, 1-2, 2-1, and 2-2, and use whatever
    works best.

    You might need a little breakout socket to access the crystal pins.

    Good Luck!
  12. James Waldby

    James Waldby Guest

  13. Fred Bartoli

    Fred Bartoli Guest

    a écrit :
    So just buy one in china...

  14. If it is 2 micro controllers, these each have an oscillator out, and an oscillator in pin.
    Remove one xtal, also the 2 caps to ground if they are there on the same chip.
    Connect osc out of the one with the xtal to osc in of the one you just stripped
    of the xtal.

    So you get his:

    | Chip 1 | Chip 2
    | |
    | osc in osc out | osc in osc out
    ---------------------- ------------------------------
    | | | | | no connection
    | | | |
    === ===
    | |
    /// ///
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