XPost: sci.electronics.design   
   From: gnuarm@gmail.com   
      
   On 2/13/2013 9:18 PM, Michael A. Terrell wrote:   
   >   
   > rickman wrote:   
   >>   
   >> On 2/13/2013 2:38 PM, DaveC wrote:   
   >>>> Why not hack in an oscillator? It would be dead-on frequency, without   
   buying   
   >>> a   
   >>>> custom-ground $80 crystal that may not work in that circuit.   
   >>>   
   >>> If I can find a 4-pin DIP oscillator at 8.86723 M I'd be tempted. But don't   
   >>> see such an animal...   
   >>   
   >> I haven't looked at standard frequencies, but you might have better luck   
   >> finding that frequency if you drop a significant digit or two.  It is   
   >> unlikely the original part was specified to 1 ppm, 100 ppm would likely   
   >> do the job just fine.  Didn't you say this was for a display?  It will   
   >> probably work fine with just five digits or even four digits of   
   >> frequency specified.  Is either 8.867 MHz or 8.868 MHz a common value   
   >> perhaps?  Really anything near 8.87 MHz should do the job.   
   >   
   >   
   >     Not if it is a video clock, to a fixed frequency monitor.   
      
   Did you miss the fact that he has specified a common crystal to nearly 1   
   ppm?  They don't make crystals that will hold a frequency to 1 ppm.  You   
   can get units specified to some 10's of ppm along with aging of similar   
   ranges.  To do better you need to temperature compensate and perform   
   other "magic" in the oscillator.   
      
   Why would you think the monitor gives a durn?  It may not take the   
   signal from an 8 MHz crystal, but 1000 ppm off should be no trouble.   
      
   --   
      
   Rick   
      
   --- SoupGate-Win32 v1.05   
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