Just to clear things up a bit, when the crystal is rated at 20 pF, that doesn't mean that it has a 20 pF capacitance. The rating is the recommended value of the capacitors that you will connect to ground from the crystal.. BTW, you can also get 3-pin ceramic resonators that have the caps built-in. They're slightly less accurate, but it's not a problem unless you need very precise timing. Daniel Imfeld ---- Original Message ---- From: "Herbert Graf" To: Sent: Monday, February 24, 2003 12:15 PM Subject: Re: [PICLIST] [PIC]: Newbie Quota (was Odd Problem) > > up (for an 18F452) and need to order a 10 Mhz crystal. They seem > > to come > > in two flavors: serial, and 20pF. My understanding is that the > > 20pF is > > the preferred one. If that is true, is it still necessary to use > > the two > > caps to ground from the leads??? > > Yes, in fact using a serial resonance crystal is not advised > for the simple reason that it will not oscillate at the marked > frequency, it will be off a certain percentage. With the PIC you > always need the caps. TTYL -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body