Build Your Own Transistor Radios

Chapter 13Oscillator Circuits

In Chapters 8, 9, and 10, oscillator circuits were used as local oscillators and converters (mixer and oscillator combination). In this chapter we will explore some “simple” analyses of a one-transistor oscillator circuit and a differential-pair oscillator. Both of these types of inductor/capacitor (LC) circuits have been used in some of the superheterodyne radio designs, and in a sense, this chapter is a “tutorial” on how these circuits work in more detail.

Although the oscillator circuits presented in this chapter are “simplified” for analysis sake and for ease of building and experimentation, the basic oscillator principles still apply. For example, the one-transistor circuit will use capacitors for “stepping ...