Oscillators with Automatic Control of the Threshold of Regeneration

The frequency of an oscillator operating just on the threshold of the oscillation generation is determined-as is well known-by the constants of the circuit only; i.e., it does not depend on the operative conditions (supply voltages) of the system. The operation in this critical state for an ordinary dynatron oscillator as well as for a dynatron with back coupling can be continuously secured by means of an arrangement working automatically. Its principle is as follows: The oscillating circuit of the dynatron feeds a rectifier which, in turn, supplies the rectified voltage to the inner grid circuit of the dynatron tube (tetrode) in such a way that its bias becomes more and more negative when the oscillation amplitude increases. Owing to this arrangement the amplitude maintains itself continuously in the critical region for which the frequency stability is very high.