The Piezo-Electric Crystal Oscillator

The zero-angle quartz crystal, having electrodes in direct contact with its surface, is used to control the output of a typical oscillating crystal circuit. The crystal is first considered as a simple mechanical oscillator, and the required plate circuit adjustment for sustained vibrations of the crystal obtained by Miler´s method on the basis of an assumed electrically equivalent crystal circuit. The electrical equivalent of the crystal is then considered as the grid circuit of an oscillating vacuum-tube circuit and the equations for the frequency and condition for oscillation derived. The effects of the tube and circuit upon the frequency of a crystal-controlled oscillator are then shown.