SCHALTUNGSANORDNUNG MIT EINER BRUECKENENDSTUFE.

摘要

The bridge network output stage comprises two push-pull amplifiers (1,2) operating in class A/B mode whose outputs are applied to the loudspeaker (6). The output of the first amplifier is also applied, via a potential divider (1,13), to the input of the second amplifier. The two amplifiers are mounted on a heatsink that includes a temperature sensor (14), e.g. a NTC or PTC resistor. The voltage across the sensor, caused by the biasing current flowing through it, is monitored by a Schmitt-trigger (15) that turns on a switch (16) at the max. permitted temperature. The switch connects the positive supply (25), through a resistor (19) and diode (18), to the second amplifier, putting it into saturation mode, with its output now grounded by a second diode (26). This results in the output power being reduced to one quarter of its normal value.