2-7
Figure 2-5.—Crystal holder.
The frequency for which a crystal is ground is referred to as the NATURAL RESONANT
FREQUENCY of the crystal. Voltage applied to the crystal produces mechanical vibrations which, in
turn, produce an output voltage at the natural resonant frequency of the crystal. A vibrating crystal can be
represented by an equivalent electrical circuit composed of capacitance, inductance, and resistance.
Figure 2-6, view (A), illustrates the symbol of a crystal; view (B) shows an equivalent circuit for the
crystal. View (C) shows an equivalent circuit for the crystal and the holder; C1 represents the capacitance
between the metal plates of the holder.
Figure 2-6A.—Crystal symbol and equivalent circuits. SYMBOL
Figure 2-6B.—Crystal symbol and equivalent circuits. EQUIVALENT CIRCUIT.
