Patent ID: 8525536

Claim:
A loudspeaker load testing circuit for detecting the impedance of a loudspeaker, the loudspeaker load testing circuit comprising: a loudspeaker having a first terminal and a second terminal; a test signal generator that is connected to the first terminal of the loudspeaker to provide a test signal of a defined bandwidth to the first terminal of the loudspeaker; an energy-storing element having a first element lead connected to the second terminal of the loudspeaker and a second element lead connected to a reference voltage; and a measuring unit that compares an output signal value at the second terminal of the loudspeaker to determine if the output signal value exceeds a threshold value, where the test signal generator comprises a microcontroller, and an amplifier that provides the drive signal, where the test signal generator further comprises a signal shaping circuit connected to an output pin of the microcontroller for providing the test signal.