Crystal filters and maybe ceramic filters are used in radio stuff
to pass only the desired frequence after mixing two signals.

Bill C.  bill@cornutt.com


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>
> >Are "ceramic filters" the same as "ceramic resonators" ?  I can go into the
> >local surplus store and find little three-lead devices labled "ceramic
> filters"
> >in all sorts of nice frequencies (ie 6MHz.), as well as "ceramic
> resonators"
> >in a more limitted range (3.58MHz)  Will both of these work in the
> oscillator

> >circuit of a PIC?
> >
> >Thanks
> >bill W
>
>
> The resonators will, but the filters have wider bandpass that could get into
> some
> real wierd operation. You could get them to oscillate in a series mode
> circuit, and
> they would run at some freq within their bandwidth (not necesarily the
> center!) but
> I'd be nervous that they might shift freqs with temp change.
>
> The filters are designed to pass a range of freqs, where a xtal is designed
> to pass
> (or be high impedance at) one frequency.
>