Frequency control technique applicable to either voltage- or current-feedback magnetically-coupled switching-transistor oscillators

Through the use of nonlinear circuit techniques similar to those normally associated with series-connected magnetic amplifiers, it is possible to modify the basic circuits of almost all of the numerous types of magnetically-coupled switching-transistor multivibrators so as to provide for frequency control of these circuits by means of a low-level dc control signal. Using two well-known types of such inverter circuits as examples, this paper describes the basic principles involved in this frequency control technique and discusses the operation of two test circuits. A primary advantage of this frequency control method is its physical simplicity and low cost.