Sinusoidal oscillators

Abstract

One might truly claim that an oscillator is the most essential, important and valuable instrument of all electronic communication devices in present use. Radio frequency oscillators are widely used in the generation of carrier waves for telecommunication systems and in the construction of non-lethal e.h.t. supplies. Industrial heaters of dielectric materials depend on r.f. oscillators. Also in the heating of electrically conducting material such as metal ingots, the induction coils are fed from power oscillators operating at lower frequencies. When transistors were not yet invented and valves were in common. use, the sinusoidal oscillators in those days employed rather cumbersome means of frequency and amplitude control. The whole set up was rather bulky due to the size of the valves. Because of these, frequencies well into the v.l.f. and u.h.f. ranges were not easily achieved. The transistor era then started. Frequency ranges, amplitude control and size of equipment improved immensely. The fet could practically replace any valve operation with slight modifications to the circuitry. The need for high power for the operation, as previously required by valves, was now eliminated [...].