Overload protection circuit for loudspeakers - incorporating interrupting relay and power and frequency measuring elements

摘要

The loudspeaker is protected against overload by a relay (4) which interrupts the circuit when an integrator (6) evaluating the load exceeds a set level in a specified time. The interruption is maintained until the level is again within limits. The integrator is frequency weighted so that the reference level falls with rising frquency. The timer is made inversely proportional to the magnitude of the signal level. A further circuit (16) detects the level of dc or sub-audio frequencies and opens the relay is these exceed the permitted value. The relay is typically solid state.