When you have studied the material in this chapter you should be able to:

• describe the use of positive feedback in the production of both sine-wave and digital oscillators;
• explain the conditions required for a circuit to oscillate;
• sketch simple circuits of sine-wave and digital oscillators;
• discuss the problems of amplitude stability in such circuits;
• describe the use of crystals in producing highly stable oscillators;
• explain the effects of positive feedback on the stability of a circuit.