In the many years that I've been designing and building opamp and other 'small signal' circuits, I've never had one fail because its output was shorted. Most opamps are perfectly happy to have their outputs shorted, but as a matter of course I always include a 100 ohm output resistor to ensure stability if the opamp is connected to a reactive load such as a length of shielded cable. Until the relay is activated, the signal is muted, and because the contact resistance is typically only a few milliohms, there's no need to add resistance to the circuit that provides the audio signal (typically an opamp). The relay is wired so that the normally closed contacts simply short the signal to earth (ground). I've described a remote receiver and transmitter that uses a relay for muting, and of all the methods available that is one of the simplest. Providing the ability to mute an audio stream is both very common and in many cases, essential. ![]() 2 - JFET (Junction Field Effect Transistor).
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