[time-nuts] have 10MHz need 19.5Mhz

Gerhard Hoffmann dk4xp at arcor.de
Sun Jun 2 19:20:59 UTC 2013


Am 02.06.2013 20:59, schrieb Chris Albertson:
> ,
>
> The Pi uses a crystal (not a TTL can, a real two lead crystal and a pair of
> 47pf caps) Both leads of the crystal attach to a pair of pins on an IC.   I
> figure I can unsolder the crystal and inject a balanced 19.5MHz signal
> directly to the IC's pins.    I know the ARM CPU just might work on a 20MHz
> clock or maybe 15MHz but the video likely would not.  I'm going to have to
> supply 19.5MHz.
One of the pins is probably the output of the sustaining amplifier,
the other one is the input. There would be no need for a balanced
signal. Just force-feed the input pin with 100 mV AC or so via cap.
Remove crystal and capacitors.
(I have not verified this against the data sheet, but that's the usual 
way.),


80 MHz for the DDS should work. Just double 3 times.

regards, Gerhard





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