Automation and Screening

Chemically, quartz is a compound called silicon dioxide. When a crystal of quartz is properly cut and mounted, it can be made to vibrate, or oscillate, using an alternating electric current. The frequency at which the crystal oscillates is dependent on its shape and size, and the positions at which electrodes are placed on it, usually 32,768 Hz. This fre-quency, which is equal to 215 in binary, makes it easy to generate a 1 Hz signal by a series of two frequency dividers in readout electronics, as needed by the designer. Because of its high stability, precision, and low power consumption, the quartz crystal tuning fork has become a valuable basic component for frequency measurements. An extensive lit-erature describes their use for a large number of other addi-tional applications.1 For low-temperature measurements, using silicon diode