Programming instructions

 National Instruments Corporation 13-1 Multisim Component Reference Guide
Chapter 13
Misc. Components
13.1 Crystal
This component is made of pure quartz and behaves as a quartz crystal resonator, a circular
piece of quartz with electrodes plated on both sides mounted inside an evacuated enclosure.
When quartz crystals are mechanically vibrated, they produce an AC voltage. Conversely,
when an AC voltage is applied across the quartz crystals, they vibrate at the frequency of the
applied voltage. This is known as the piezoelectric effect and quartz is an example of a
piezoelectric crystal.
The piezoelectric characteristics of quartz give the crystal the characteristics of a very high Q
tuned circuit. The piezoelectric effect of quartz crystal links the mechanical and electrical
properties of the resonator. Electrode voltage causes mechanical movement. Likewise,
mechanical displacement generates an electrode voltage.
An equivalent circuit for a crystal shows a large inductor in series with a small resistance and
a capacitance. When mounted in a holder with connections, a shunt capacitance is added to
the equivalent circuit. The resultant equivalent circuit means that the crystal has both a series
and parallel resonant frequency very close together.
Oscillators that employ crystals, typically quartz, offer excellent oscillation frequency
stabilities of 0.001 percent. Crystal oscillators are used in digital wristwatches and in clocks
that do not derive their frequency reference from the AC power line. They are also used in
color television sets and personal computers. In these applications, one or more “quartz
crystals” control frequency or time.
Another much more efficient transducer material than quartz is PZT. This ceramic material is
ferroelectric and is made up of lead and other atoms, Ti or Zr. PZT consists of randomly
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