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Re: Variable Capacitance and Inductance

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> Original poster: "rheidlebaugh by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>
> Ed/Matt : as I havs seen many changes in equipment through the years
> Including the use of the COLPITS RC only oscilator for stability to the
> current crystal controled systems of the lap top computer time base.
> Frequency drift is and has been a problem for all physicly constructed
> systems in electronics. An engineer designs a system, but a tech re works it
> to make it work in the real world. There is no resonant circuit made that is
> not affected by its enviorment including crystals. It is not reasonable to
> think an open coil like a TC would not be subject to every change around it
> including sun, moon, weather , and a mad wife.
>    Robert  H       ( get off that list and talk to me!!)


	Others may be interested in this.  The Colpits oscillator is one of a
number of feedback oscillators originally developed for use with tubes,
but equally suitable for use any active amplifier; ALL use an L/C
circuit for frequency determination.  In the Colpits the inductor is
untapped, connected on one end to the plate of the tube and on the other
end to the grid (with suitable DC blocking, of course).  Two capacitors
are used in series.  Their ends are connected to the inductor and the
tap (junction of the two capacitors) to the filament.  Look in any radio
handbook for "Colpits, Hartly, Meissner, etc.".