Simple mute based on a micro relay and a BC549 for switching. Pedal friendly and compact it can retrofit to a variety of circuits as an add-on, or incorporated into your own build. The PCB module can be configured for standalone use or in various mix and match combinations.
This is a very reliable circuit, and automatically un-mutes the signal when there is no power. To mute the signal, a transistor is turned on that energises the relay coil and pulls the signal to ground. The relay is a miniature DPDT (double-pole, double-throw) type. This switch has an incredibly short set and release time, around 3ms, so it operates much more effeciently than a standard mechanical switch. The goal is to minimize clicks and pops in the audio circuit while turning the mute on and off.