At 09:51 PM 12/30/99 -0600, you wrote:
>William K. Borsum wrote
>
>>Also, be sure the load caps
>>are correct--most watch
>>crystals I get from Digikey
>>or Mouser are around 12.5
>>pF--remember this includes
>>trace capacitance, etc.  NOT
>>critical, but it does seem to
>>help to be close.
>
>I've made it work before but never quite understood it.  What does this
>mean?  The 2 caps on the crystal should match the capacitance of the
>crystal?  Can you use the catalog value for the crystals pF as given in the
>catalog?

I do.  Also check the MicroChip data sheets for their recommendations.
There are a number of Ap-Notes on the subject as well. In general values
from 10 to 30 work reasonably well, along with that 100 K carbon Comp
series resistor.

Remember that watch crystals start fairly slowly--a few seconds is not
unusual.

Kelly

William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems
<borsum@dascor.com> & <www.dascor.com>San Diego, California, USA