Automatic source switch for domestic audio system - has source level detectors to latch monostables when signal reaches threshold and connect active source t preamplifier

摘要

A signal level detector (45) for each channel activates a monostable (50) and connects the source to the preamplifier using a MOS switch (52), maintaining the connection as long as the signal is uninterrupted for a preset period. A group of inputs can be used with one detector by multiplexing and testing each signal level periodically. - Also a source can be assigned priority by connecting the output of its detector to one input of a monostable. In such a case, the other sources are grouped on the alternate input using an AND gate.