[time-nuts] pulling oscillators

[J. Forster]

Capacitively couple a Varactor (or back biased diode) to the circuit and
vary the diode bias to tune.

-John

============


> Hello all:
> I've developed a need for pulling crystal oscillators built in to pll
> circuits. These are cmos, and have the common style oscillator circuit
> built in. The crystal is across an inverter in the chip, and there is a
> small cap between each end of the crystal and ground.
> The chips are pll's in radio transceivers, early at that.
> I could carefully remove the crystals and caps, simply driving the
> non-inverting input on the chip with the reference, but I would rather
> simply tack on a very small cap and "pull" the crystal oscillator with an
> external reference signal of the right frequency.
> Anyone out there tried this?
> Thanks
> Don
>
>
>
> --
> "Neither the voice of authority nor the weight of reason and argument are
> as significant as experiment, for thence comes quiet to the mind."
> R. Bacon
> "If you don't know what it is, don't poke it."
> Ghost in the Shell
>
>
> Dr. Don Latham AJ7LL
> Six Mile Systems LLP
> 17850 Six Mile Road
> POB 134
> Huson, MT, 59846
> VOX 406-626-4304
> www.lightningforensics.com
> www.sixmilesystems.com
>
>
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