NPN sawtooth signal generator

摘要

A sawtooth generator can also be built with a single transistor operated in a highly unusual manner. Here the NPN transistor is wired the wrong way round in the circuit, with a positive voltage on the emitter, and the base lead is left open. The voltage on the capacitor gradually rises to approximately 9 V. At this point the transistor suddenly starts conducting and discharges the capacitor to approximately 7 V.