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Crystal testing

markm6164

Jan 22, 2012
118
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Jan 22, 2012
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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
 

GreenGiant

Feb 9, 2012
842
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Feb 9, 2012
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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.
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
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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.

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
 

davenn

Moderator
Sep 5, 2009
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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.

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

attachment.php


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

attachment.php


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
 

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