| 摘要 |
916,033. Valve oscillator circuits. SOLARTRON ELECTRONIC GROUP Ltd. July 10, 1959 [July 21, 1958], No. 23384/58. Class 40 (6). [Also in Group XXXV] In a sinusoidal oscillation generator, the voltage waveform is sampled over a small part of a cycle near a peak, compared with a reference voltage and the difference used to generate a correcting pulse which is combined additively with the generated waveform so as to maintain the sampled amplitude constant. As shown, amplifiers 10, 11 each have a phaseshift of 90 degrees with unity gain at the oscillation frequency, effected by series resistors 12, 13 and feedback capacitors 14, 15. The oscillation is maintained by a feedback amplifier 16 having unity gain. The sum of a sinusoidal output voltage from amplifier 10 and a negative reference voltage from a source 17 is applied to a gate 18. The gate 18 is opened at a positive peak of the output voltage from the amplifier 10 by an amplitude selector 23 deriving clipped positive and negative-going pulses from a summation of the output of amplifier 11, rectified by a diode 19; the output of amplifier 11, reversed in phase by an amplifier 20 and rectified by a diode 21, and a portion of the output of amplifier 10, reversed in phase by an amplifier 26 and rectified by a diode 21. The output pulse from the gate, representative in amplitude and sign of the difference between the sampled amplitude and the reference voltage is fed to the input of the feedback amplifier 16 to modify the output waveform of the amplifier 10 so as to maintain the sampled amplitude constant. It is stated that the amplitude correction can be applied n times per cycle, or every nth cycle, where n is a positive integer. To ensure constant peak amplitude from the commencement of oscillation, the oscillators 10, 11 are clamped by switches 51, 52 that are simultaneously opened to start the oscillation. Specification 849,903 is referred to. |
