Where to put a crystal?

Discussion in 'Wireless & RF Design' started by nerdegutta, May 1, 2010.

  1. nerdegutta

    Thread Starter Moderator

    Dec 15, 2009
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    785
    Hi.

    I have this schematic, built on a homebrew PCB. I have build some FM minitrasmitters, but they are jumping up and down the frequency.

    I also have a lot of crystals, and I would like to use one of them to stabilize the frequency. Is this possible?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
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    You need a decoupling capacitor across the power supply. As shown, the battery and it's wiring are part of the RF current path..

    Fit a 0.1uF as near to the R7 / L1 power connections as possible. That should help with stability.

    Also, if you connect the antenna to a tap on the coil (possibly a quarter of the way down from the positive end), it should be even more stable and give better output.
     
  4. nerdegutta

    Thread Starter Moderator

    Dec 15, 2009
    2,515
    785
    Hi.

    Bertus:
    Thanks for the link. Lots of good reading. :) Need to buy some IC's.


    RJenkins:
    I've edited the schematics, but I'm not sure where to put the 0.01uF near the R7 / L1.
     
  5. Udra

    New Member

    May 27, 2010
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    Hello,Bertus, thanks for the link. Lots of good reading
     
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