"Series" vesus parallel or parallel versus series - - it all boils down how one is taking advanatge or making use of the the *impedance* that the reactive components exhibit that make up a crystal - the two (equivalent) *internal* caps and the high-Q inductor. Now, obvioulsy a crystal doesn't literally have an inductor inteanally - but for the purposes of analysis and modeling - it does. So - a crystal's characteristics are a matter of how one 'plays' with this little two-pin network and what the oscillator circuit responds to most favorably - a 'series' low-Z path or a Hi-Z network that *resonantes* with an external ('parallel') 'load' (as it's called) capacitance. Like any network - at resonance a 'Q rise' in various circuit parameter vales occurs - make use of this characteristic with properly ground crystal and you have an on-frequency oscillator. Jim ----- Original Message ----- From: "Nick Veys" To: Sent: Friday, March 01, 2002 1:11 PM Subject: Re: [EE]: Crystal types... > > >When purchasing a crystal, how do I tell the diff between series-cut > > >and parallel-cut? The 16F872 datasheet specifies parallel req'd, as > > >series may give a diff freq. > > > > > > > Check the catalog listings. Digikey and Mouser both specify > > a load capacitance or list them as 'series' for each crystal type. > > > > If they list a load capacitance (typically around 20pF), > > they're parallel crystals. If they say 'series', they're series. :=) > > I've wondered about this too, the only descriptions I've been able to > get were physics of crystals and other such nonsense! :) > > Not what they are, but how to use them. > > The parallel crystals specify the load capacitance, and I've used those > and they work great. > > So how do you use the series? With the same capacitors? What rating? > I've seen "series" crystal circuits with several buffers and stuff, way > too much to be practical. > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body