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Check frequency

Discussion in 'Electronic Basics' started by ClueLess, Dec 16, 2009.

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  1. ClueLess

    ClueLess Guest

    Hi all

    I have a requirement to exactly adjust the frequency of a
    microcontroller system (8051) that works with the 32768 Hz watch
    crystal.

    I am not an electronics engineer but a hobby type. I will thank you to
    please let me know how the system can made to work exactly at the
    above frequency. Trimmers are provided. my understanding is that you
    need an oscilloscope to do this. In that case what kind should I go
    for? Os is there a simpler methods?
     
  2. Phil Allison

    Phil Allison Guest

    "John Fields"

    ** Shame how even the cheapest DSOs have built in frequency measurement to
    5 decimal places.


    .... Phil
     
  3. Phil Allison

    Phil Allison Guest

    "ClueLess

    ** To get the frequency exact, you need resolution better than 1 Hz - one
    way is to use a frequency counter that can be set to count for 10 seconds -
    giving you 327 thousand odd counts on the display.

    Picking up a signal voltage from the crystal without disturbing it is a
    problem too - most counters would stop the oscillations if directly
    connected.

    Time for a Reality check:

    Just how " exact " do you really need it ??

    A watch crystal will be within about 30ppm (or 1 Hz ) with no adjustment.

    To get better accuracy, you will need at a dual trace scope and a quartz
    clock that keeps good time.

    Dunno why you are playing with uPs when you have no scope.


    ..... Phil
     
  4. Jasen Betts

    Jasen Betts Guest

    Set the device up to count cycles between input pulses and feed it the
    1 Hz pulse train from a GPS, trim until you get close enough to 32768
     
  5. Phil Allison

    Phil Allison Guest

    "Jasen Betts" <>

    ** Sheep shagger extraordinaire.


    ** The crystal will be 32.768 kHz out of the box.

    Idiot.



    ..... Phil
     
  6. Phil Allison

    Phil Allison Guest

    "John Fields"
    "Phil Allison"


    ** Pedantic bollocks.

    The OP is a novice and has no scope at present.

    A low price ( ie $300) DSO is just what he should get.


    ..... Phil
     
  7. Phil Allison

    Phil Allison Guest

    "John Fields"
    "Phil Allison"

    ** You don't think straight at all.

    Never have.
    ** Meaningless drivel.



    ...... Phil
     
  8. ClueLess

    ClueLess Guest

    Thank you very much got your very detailed suggestions, I will look
    for a frequency counter and try as you said.
     
  9. Phil Allison

    Phil Allison Guest

    "ClueLess"
    John Fields

    ** Don't do that.

    That advice is crap and will not work.

    Get a scope with two traces.

    But first tell US what sort of accuracy you NEED and why !!



    ...... Phil
     
  10. Phil Allison

    Phil Allison Guest

    "John Fields"
    "Phil Allison"
    ** Fraid it is just more of your crazed, autistic crapology.


    ** Fraid it is just more of your crazed, autistic crapology.



    ....... Phil
     
  11. Phil Allison

    Phil Allison Guest

    "whit3rd"
    ClueLess
    John Fields
    Er... no, that's not right. If you have a suitable reference
    frequency source, you can watch the pretty Lissajous figure
    on an X/Y oscilloscope (no dual channel, no counter) and if
    it goes through a cycle in 100 seconds, with 0.1 second
    stopwatch accuracy, you've just made a frequency
    measurement with .001 Hz accuracy. For your
    32 kHz crystal, that's a second per year kind of accuracy.

    A frequency counter is a convenient and quick solution, but
    it is NOT required nor is it superior in accuracy.

    ** Ask JF where the OP can get an affordable counter that
    reads a frequency in Hz to seven decimal places - as in his
    " 32768.XXXXXXX Hz ".

    His magic 10 turn crystal PU loop need to be patented too.


    ....... Phil
     
  12. Phil Allison

    Phil Allison Guest

    "John Fields"
    "Phil Allison"
    ** It was plucked right out of your arse.

    Just like all your fucking absurd advice.



    ** You are fresh out of sanity - too.


    .... Phil
     
  13. Phil Allison

    Phil Allison Guest

    "John Fields"
    whit3rd
    ** The autistic JF fuckwit cannot even read.

    The meaning was very clear.

    ** My gawd - this has gone beyond all previous limits of JF's monumental
    stupidity.


    ** No such thing was ever said.

    JF is completely off his tiny fucking head.



    ..... Phil
     
  14. Phil Allison

    Phil Allison Guest

    "John Fields, Autistic "
    ** Errr - because you repeatedly failed to comprehend how Lissajous
    patterns are commonly used to compare two frequencies ??

    Is the great JF completely ignorant of a such a simple technique ???

    Must be so - everything he says screams it.

    Here is the idea:

    " If you have a suitable reference frequency source, you can watch the
    pretty Lissajous figure on an X/Y oscilloscope (no dual channel, no
    counter) and if it goes through a cycle in 100 seconds, with 0.1 second
    stopwatch accuracy, you've just made a frequency measurement with
    0.001 Hz accuracy. For your 32 kHz crystal, that's a second per year
    kind of accuracy.

    A frequency counter is a convenient and quick solution, but
    it is NOT required nor is it superior in accuracy. "


    ** Fraid it is all true.....

    The demented JF has forgotten how to think analogue.

    Cos he has forgotten how to think at all.


    ..... Phil
     
  15. Phil Allison

    Phil Allison Guest

    "John Fields is off his Head"

    ** It was plucked right out of your arse.

    Just like all your fucking absurd advice.



    ** You are fresh out of sanity too, asshole.

    Completely lost touch with reality.




    .... Phil
     
  16. Phil Allison

    Phil Allison Guest

    "Clue Less = John Fields "

    ** ROTFL !!!

    This is all too weird for me.




    ...... Phil
     
  17. Jasen Betts

    Jasen Betts Guest

    use a tuned probe. 32768Hz crystals work good for probes.
     
  18. Phil Allison

    Phil Allison Guest

    "Clue Less = John Fields "

    ** No way that includes autistic retards like YOU then.

    FOAD - septic fuckhead.


    ...... Phil
     
  19. Phil Allison

    Phil Allison Guest

    "John Fields, Autistic LIAR "
    ** Errr - because you repeatedly failed to comprehend how Lissajous
    patterns are commonly used to compare two frequencies ??

    The great JF is completely ignorant of a such a simple technique.

    Here is the idea:

    " If you have a suitable reference frequency source, you can watch the
    pretty Lissajous figure on an X/Y oscilloscope (no dual channel, no
    counter) and if it goes through a cycle in 100 seconds, with 0.1 second
    stopwatch accuracy, you've just made a frequency measurement with
    0.001 Hz accuracy. For your 32 kHz crystal, that's a second per year
    kind of accuracy.

    A frequency counter is a convenient and quick solution, but
    it is NOT required nor is it superior in accuracy. "


    ** Fraid it is all true.....

    The demented JF has forgotten how to think analogue.

    Cos JF has autistic dementia and cannot think at all.



    ..... Phil
     
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