Test oscillators

Discussion in 'General Electronics Chat' started by vventura, Jan 21, 2008.

  1. vventura

    Thread Starter Member

    Jan 21, 2008
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    Hello all,

    I'm new into electronics, i started by building a training kit which at the end didn't work, all measures taken by me seem right, at the end the troubleshooting guide, points either to the PIC or the 8 mhz ceramic oscillator. How can I test the ceramic oscillator, on the input I have 5v, but on the output I don't have anything, can I measure the output with a multimeter?

    Best regards
    Ventura
     
  2. rwmoekoe

    Active Member

    Mar 1, 2007
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    you can measure the output best using an oscilloscope or a scopemeter (the ones that looks like a DVM w/ large graphic LCD screen).

    if u can guess around what happens at the output of the oscillator, using a voltmeter the readings might be around half the 5v voltage, when the oscillator is running. or maybe the readings will always change if you use a DVM.

    once you got the oscillator running, just troubleshoot the PIC.
     
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Is your ceramic element really an oscillator, or is it a resonator? A resonator has to be imbedded in a feedback loop in order to make an oscillator. You can't get an output from a resonator by simply connecting it to a power supply.
    Can you post a schematic of your training kit?
     
  4. vventura

    Thread Starter Member

    Jan 21, 2008
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    You might be right about oscillator/resonator doubt I thought I was the same thing. The scheme is here, the leds never go on, to do some debug I took the pic out and connected the negative to the led and all of then worked fine. So it think the problem is either in the resonator/oscillator, or in the pic.

    You can see the scheme here: http://picasaweb.google.com/ventura.vitor/Electronics/photo#5158256773802798290
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    That is definitely a resonator.
     
  6. vventura

    Thread Starter Member

    Jan 21, 2008
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    So in this case how can I test the resonator in order to find out if its broken or not?
     
  7. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Do you have access to a CMOS logic gate (74HC00, 02, or 04), and an oscilloscope or a frequency counter? Otherwise, it's tough to test.
     
  8. vventura

    Thread Starter Member

    Jan 21, 2008
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    I can have a osciloscope, but nothing else..
     
  9. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    If you want to test your resonator (I doubt it is bad), you will need a 74HC00, 02, or 04, and a 5 volt DC power supply.
     
  10. thingmaker3

    Retired Moderator

    May 16, 2005
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  11. vventura

    Thread Starter Member

    Jan 21, 2008
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    Do you think that its the PIC that is broken? If its true then that is even worst for me :(
     
  12. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Who knows? Who did you buy this training kit from? Do they have a web site? I would like to see the web site, and maybe an online manual.
     
  13. thingmaker3

    Retired Moderator

    May 16, 2005
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    There's not a lot that can go wrong with a resonator. A bit of static electricity can doom a microchip, though. Go ahead and test the resonator to be sure, but be prepared for the worst. You might indeed have to shell out a few dollars (plus shipping) for another PIC.
     
  14. pebe

    AAC Fanatic!

    Oct 11, 2004
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    Make up a probe like this. Fit a 1nF cap from one of the oscillator pins to the cathode of a small signal diode. Anode of the diode to ground. Fit a 47K from cap/diode junction to your multimeter. Neg of your meter to ground. If the oscillator is working, you will have volts.
     
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