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Crystal testing

Discussion in 'General Electronics Discussion' started by markm6164, Aug 17, 2012.

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  1. markm6164

    markm6164

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    Jan 22, 2012
    Can anyone point me in the direction of a simple useable circuit i can build for testing crystals? I have seen loads of circuits as i am googling around but not sure which to build. I don't want to use the usual led indicator circuit. I just want to be able remove the crystal from a circuit. Connect it to the test circuit and scope the frequency to show its working and at what frequency. I don't have a specturm analyzer only an oscilloscope.

    Many thanks

    Mark
     
  2. GreenGiant

    GreenGiant

    830
    6
    Feb 9, 2012
    just set up a small quick connect that you can plug the crystals into that's got a small power supply (voltage based on the crystal being tested) and the scope probes connected to it, that's all you need, the hardest part will be if you have surface mount crystals, and dialing in the scope to the right window.
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Does this mean he doesn't need an oscillator? ... Just a psu, socket and scope? :rolleyes:

    Sorry, I have no self control. I just couldn't restrain myself. Besides, the opportunity was irresistible :D Please forgive me. ;)

    Chris
     
  4. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    NO, Greengiant :) the crystal will have to plug into an oscillator circuit.
    You may be thinking of oscillator modules like this.....

    [​IMG]

    one of the easiest circuits would be a colpitts oscillator here's a garanteed working cct I have used often....

    [​IMG]

    That pdf file John has linked to give plenty of ideas of different types of oscillators
    including the colpitts

    to the Op .... you are most likely going to need a frequency counter unless you have a really decent scope capable of good resolution well above any crystal freq you are testing

    freq counters are pretty cheap these days for one that goes to ~ 1GHz

    Ohhhh .... if you are going over ~ 4MHz you may need to upgrade the transistors to a higher freq transistor, a BF494 or something similar

    cheers
    Dave
     

    Attached Files:

    Last edited: Aug 18, 2012
  6. davenn

    davenn Moderator

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    Sep 5, 2009

    Attached Files:

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