[time-nuts] Why these Crystal Frequencies?

Rex rexa at sonic.net
Wed Dec 14 22:40:10 EST 2011


14.31818  is 4x the analog color burst (~3.58)

18.432   divides cleanly for baud rates. I've used it as a PIC clock for 
that. I think some of the others may be too, but I didn't recognize or 
do the math to see.

On 12/14/2011 7:13 PM, Brooke Clarke wrote:
> Hi Pete:
> Maybe you can shed some light on the common xtal frequencies table 
> where there's no explanation given?
> http://www.prc68.com/I/pdf/Crystal_Freq.pdf
> An answer is not it's an "even" frequency or "it's an even binary 
> frequency. That's true for most of these and the factors are part of 
> the table above.
> The question is why do they exist?
> such as:
> 32.0 kHz

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