Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!cs.utexas.edu!convex!mic!letni!rwsys!kf5iw!k5qwb!lrk From: lrk@k5qwb.lonestar.org (Mr. Lyn R. Kennedy) Newsgroups: sci.electronics Subject: Re: XTAL not oscillating at marked frequency Keywords: wierd crystal stuff Message-ID: Date: 21 Jun 91 21:43:52 GMT References: <15604@exodus.Eng.Sun.COM> Organization: Radio Amateur k5qwb Lines: 34 bender@oobleck.Eng.Sun.COM (memory fault - core dumped) writes: > > What exactly is the failure mode here? Do crystals go "bad"? Here's what > the oscillator circuit looks like: > > +-------------------||-------------------+ > | 0.1uF | > +--/\/\/\--+ +--/\/\/\--+ > | 330 | | 330 | > | |\ | | |\ | > +---| o----+---+---|[]|-------+----| o---+ > |/ | 24 MhZ |/ > LS04 | LS04 > | |\ > +----| o--------> 24 MhZ out to divider > |/ > LS04 Welcome to reality. There is nothing in this circuit to make the xtal operate at 24 Mhz. If it's an 8 Mhz fundamental, you should expect it to work there. You might try a series-tuned circuit in place of the 0.1uF but I doubt you'll find any simple way that works well. Best bet is to get a good circuit out of a handbook and put it's output into one of the LS04 inputs. ------------------------------------------------------------------------- 73, lrk@k5qwb.lonestar.org Lyn Kennedy K5QWB @ N5LDD.#NTX.TX.US.NA P.O. Box 5133, Ovilla, TX, USA 75154 -------------- "We have met the enemy and he is us." Pogo --------------