The LM3876 is an integrated power amplifier designed for high-end applications. This video shows a LM3876 (LM3876TF) and the respective muting circuit under test on a breadboard. The muting circuit is designed so that it mutes the LM3876 once the amplifier is turned off. It uses a TLP521-1 optocoupler to control the current coming from the mute pin. As you can see, bypassing the optocoupler's transistor will disable mute at turn off. The oscilloscope measures the voltage drop across the resistor connected to the mute pin of the LM3876. Connected to the output is a Visaton FR 10 4Ohm driver, reproducing the music "Lullaby" by "Ghost".

P.S.: Sorry for the poor sound quality! The MP3 player that I normally use to record the soundtrack was being used as a signal source for this test.

Created: October 15, 2011

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