QUARTZES | ||||
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Not
there is amateur radio operator, CB, SWL or fan of
electronics in kind that, sooner or later, does not have to familiarize
with quartzes, that is with those component whom, you to an oscillator binds
together, generate one characterized frequency a highest degree of
stability. We begin therefore with shown the symbol electrical
worker of the quartz crystal, that it is that one brought back to the left
of figure 1 and whose acronym it is
XTAL.
Fig. 1
In
the left part of
the figure there is the symbol is
brought back electrical worker of the quartz, to right a common model in
its outer garment. In
truth the component of which we are speaking can assume various aspects, but
that more commonly famous one is brought back on the right of figure 1.
Draft of a metallic small box, that it can be of plastic or glass, from
which leaked
two pinsi, that they represent the electrodes and on which is generally
written the value of the fundamental frequency.
Within the covering, like indicated in figure 2, it is present a floppy
disk, similar to smerigliato, thinnest and covered the glass, on the
two faces, with a thin silver layer. The two faces of the crystal are
connected, through two small motivatings force, that they also act as from
elements of support, with the two reofori.
Fig.
2. - Within the covering of the quartz, that it can be of metal, plastic
or glass, it is present a floppy disk of thin mineral much, in silver part
covered and connected, through two small motivatings force, to electrodes of the
component. The
thickness of the quartz determines the frequency of the component.
Therefore, its realization, that it demands a process still
today by hand, assumes great importance. The thinning of the plate,
illustrated in figure 2, happens through grinding, with the use
of appropriate blots some, while the putting in frequency happens
manually. We make an example. We suppose that a quartz from 9,545 must be
prepared MHz. Well, in such case MHz is necessary a plate from 10 to
which, through the molatrice, they are made to catch up the 9,54 MHz
approximately. Then the silvering is carried out and, next plate in the points is lost weight manually
in which it has not been covered with silver. In case, with this last operation, that is the mineral removal, had to turn out excessive
and the higher frequency of the prefixed value, then will be necessary to
add to the plate of the small amounts of graphite, until the attainment
of the established value of frequency. A such improvement can be obtained
with the use of one matita. Obviously, these participations must be are
executed in its turn with the quartz connected with an oscillator,
connected with a frequency meter. Unfortunately, the working by hand of the
quartz affects strongly the price of the component who reveals an
element from the high cost. Once
caught up the exact value of frequency, the plate comes inserted
in its contenitore, from which it comes removed the air and
introduced an inert gas. It
is not possible, in fact, to leave the inside of the quartz the air, that
it could create oxidation phenomena and alter the value of the frequency
of job of the component. |
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