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Crystal oscillators were invented in the 1920s. Cady made one of the first ones in 1921. Miller patented both his own and Pierce's circuits in 1930 [1]. Pierce patented both his own and Miller's circuits in 1931 [2], and after some legal arguing in the courts, Pierce re-patented both circuits again in 1938 [3]. Sabaroff's quartz crystal version of the Colpitts LC oscillator was published in 1937 [4], and Meacham's resistance bridge circuit was published in 1938 [5]. Butler published his article on VHF harmonic oscillators in 1946 [6]. Goldberg and Crosby published their article on cathode coupled or grounded grid oscillators in 1948 [7].
The U.S. Army Signal Corps funded an intense quartz crystal development program during and after World War II and funded a small amount of oscillator circuit development along the way. Edson did a study of VHF harmonic oscillator circuits in 1950 181 and published his classic book on vacuum tube oscillators of all types in 1953 [Q]. In 1965, Firth published his design handbook on the Pierce circuit and the Butler common base harmonic circuit.
The early oscillators used vacuum tubes, which had limited life and were, therefore, high-maintenance items. Consequently, there was a considerable advantage in using a one-tube oscillator circuit, as com pared with a two-tube circuit. Strong emphasis was placed on getting the maximum power out of the oscillator circuit, since this meant that fewer power amplifier tubes were required in a transmitter. Vacuum tubes operated at power supply voltages of 150-300 VDC, which permitted large voltage swings and made it extremely easy to overdrive the crystal's dissipation limit or even fracture the crystal.
With the advent of transistor and IC circuits, the emphasis was placed on performance. Transistors are very small and have indefinite life, so in many cases, the number of transistors used in an oscillator circuit is almost irrelevant. The lower power supply voltage used in transistor circuits has reduced the crystal overdrive problem to more manageable proportions. And to get better frequency stability, oscillator circuits are now routinely designed with low power output, since it costs so little to add an amplifier stage.