Hi > On Feb 17, 2021, at 6:31 PM, Hal Murray <hmur...@megapathdsl.net> wrote: > > > kb...@n1k.org said: >> …… and there are whole families of crystal cuts that have been optimized for >> use as thermometers. There is no need to compromise on something like an AT >> or SC if you are after temperature. There are lots of different cuts to pick >> between. > > How many degrees of freedom are there if I want to make a crystal? What > fraction of the space has been explored?
Axis orientation is defined by the crystallography of the materiel. That’s been pretty well understood for a long time https://www.nature.com/articles/154157b0 <https://www.nature.com/articles/154157b0> > > Rotation in 3D has 3 degrees of freedom, but we are making a plane so I think > we get one back. > > How accurately does a the crystal have to be oriented? If I'm doing a brute > force search, how close together would I have to make test samples in order > to > not jump over something interesting? Fractions of a degree on each axis > > > If I pick a type of cut, say AT, does the shape (round, rectangular) effect > the temperature profile? Yes. It also impacts if it works at all. Get the shape wrong for this or that orientation and you get nothing. You also have a number of vibrational modes. Each of them is excited by different electrode configurations and mounting structures. > If it's rectangular, that may add another degree of > freedom. Turning an “idea” into a production capable part involves making many batches of test samples. Think in the thousands of batches and hundreds of parts in each batch. You have a “search” process at the blank chopping level. You also have a search at the resonator fabrication level. Getting the chopping part right is only a small part of the whole process…. One example: I may have a wonderful “Bob Cut” that does a fine job over temperature. If a 5 Mhz 3rd overtone “Bob Cut”has a Q of 100,000 it isn’t going to show up in a lot of OCXO’s …..The temperature stuff relates to the blank chopping part. The Q gets into the details of the resonator design. Typically this design stuff gets done by folks who have PhD’s in this or that sub-type of crystal design. Even with that PhD, you still do these “mass search’ sorts of designs. A full answer on most things crystal might take a couple books worth of detail ….. Bob > > > -- > These are my opinions. I hate spam. > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.