On Fri, 29 Jul 2005 16:47:39 -0700, "John Smith"
wrote:

Wes:

Of course there are millions, if not billions of 'em in my computer, encased in
the chips there, but having viewed many, many spec sheets and diagrams of the
internal geometry of the chips, can't say I would really bet there is a
colpitts commanding the freq of the bus in my computer, nor the daughter boards
in their...(sic)

Well, there is usually only one oscillator, not billions, and I'm sure
that I said "Pierce", not Colpitts.


Now you might be right, it is just an argument I must defer from, since
reliable data one way or another cannot be obtained without expending more
effort than I am prepared to expend... I'll even grant you a win by
default--the argument simply is not deserving of my time, and anyone with
access to the internet can look at a diagram depicting components used in the
clocks of "modern circuits."

I just did a little "data mining." Out of the last 188 posts in this
forum, you made 47 of them, or 25%. Perhaps if you "expended some of
the effort" that you waste writing every fourth post you would have a
little time to actually research what you're saying -before- you write
about it. Just a thought.

BTW, I wasn't trying to "win", I was trying to correct the insane idea
that knowledge of "old time" oscillators is unworthy of study when
talking about "modern" radios. The fact that this belief exists is
proof positive that questions about these things should remain in the
amateur exams. But expending effort to learn the basics is too much
effort for "modern" hams.

Plus the applicant's self-esteem might suffer if he has to gain a
little knowledge of electronics, antennas, transmission lines, good
operating practice and Morse code, so I suppose the FCC should just
issue licenses to anyone who makes a request.



"Wes Stewart" wrote in message
.. .
On Fri, 29 Jul 2005 12:33:53 -0700, "John Smith"
wrote:

Ham op:

Just drew the circuit of a xtal in the feedback of a high precision op amp
circuit... hmmm, could be colpitts--but can't see the resemblance...

Just drew the circuit of an xtal chucked in the feedback line of a set of
logic
gates... hmmm, that could be colpitts too, but again, can't see the
resemblance...

Draw a transistor (FET, or triode) with a capacitor from collector
(drain, plate) to emitter (source, cathode), an inductor from
collector to base (gate, grid), and a capacitor from base to emitter.

Ground the emitter and everything connected to it and take the output
from the collector. You have a Pierce. Replace the inductor with a
crystal and you have a Pierce oscillator with the crystal operating in
the anti-resonant mode.

Ground the collector and everything connected to it and take the
output from the emitter. You have a Colpitts. Replace the inductor
with a crystal and you have a Colpitts oscillator with the crystal
operating in the anti-resonant mode.

Insert a crystal between the emitter and the two capacitors connected
to it and take the output from the emitter and you have a crystal
oscillator operating at series (or overtone) resonance.

Stick a varactor in there someplace and you have a VCO or VCXO.

Clapp, Vacker, Franklin, Butler.... they are all just variations on an
old theme.