Short-cct. and overload protection for amplifier - has temp-sensitive resistor and series resistor controlling transistor cut-out switch

摘要

The short-circuit and overload protection, for an amplifier, has its cut-out element triggered both by overcurrents and by increases in temperature. The cut-out element consists of a transistor switch at the input of the amplifier being protected and controlled by a second transistor. A resistor is connected into the amplifier's input line and the voltage drop across it is used to control the second transistor. A temperature-sensitive resistor acts as bias resistor for a third transistor whose collector output is coupled to the second transistor's base input.