Practical Designing of Measuring Signal Generators
The commercial production of generators in the USSR, Russia and foreign countries began several decades ago. During this period, a great number of different circuits—from the simplest ones based on two lamps or transistors and a RC circuit to complex indu
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Practical Designing of Measuring Signal Generators
The commercial production of generators in the USSR, Russia and foreign countries began several decades ago. During this period, a great number of different circuits—from the simplest ones based on two lamps or transistors and a RC circuit to complex industrial generators—were proposed. Certainly, it is impossible to consider them in one book. Therefore, we have to limit this overview only to some industrial oscillators from the leading world manufacturers,1 and only to those of them that, in the author’s opinion, represent the key milestones in the history of generators. Since the development of the first industrial oscillators, they have been steadily improved: enhancement of designs, application of advanced materials and technologies, addition of new components. At the same time, their electrical circuits have become increasingly complex. Designers have been continuously improving all parameters of generators by introducing frequency-determining circuits with optimal combination of components, original engineering solutions aimed at stabilizing amplitude and minimizing nonlinear distortions. Since one of the key parameters that determine a long service life of RC measuring signal oscillators is a low harmonic distortion of the output voltage, we shall analyze their circuit designs in terms of reducing the total harmonic distortion. It is demonstrated in Chaps. 6 and 7 that the total harmonic distortion is mainly determined by the amplifier and the oscillation amplitude stabilization circuit. Therefore, we shall carry out the analysis in this direction. Initially, the oscillation amplitude stabilization was achieved using the natural nonlinearity of amplifiers in the oscillating system. However, it became clear soon that the low distortion level could not be achieved, so the designers focused on using inertia nonlinear elements, such as incandescent lamps and thermistors, in the stabilization circuits. Without getting too deep into the history, we can note that one the first industrial generators is the model 200 A designed by Hewlett-Packard [1]. Its driving oscillator (DO) was implemented on the basis of two pentodes. An incandescent lamp was used for stabilization of amplitude. Later, in 1938–1946, 1
The oscillator circuits presented below are simplified; therefore, the author is not liable for their proper functioning and metrological characteristics.
Yu. K. Rybin, Measuring Signal Generators, Signals and Communication Technology, DOI: 10.1007/978-3-319-02833-0_9, Springer International Publishing Switzerland 2014
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9 Practical Designing of Measuring Signal Generators
the whole family of generators (200B, 200C, 200CD, etc.) was developed on the basis of this device. Among Russian industrial RC generators, the measuring oscillator G3-33 [2] should be mentioned. It was commercially produced during the 1970s. Its DO was based on two high-vacuum pentodes with a resistance-capacitance phasing Wien circuit. The thermistor TPM-6/25 was used for ampli
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