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Topic: Need to completely mute audio using transistors (Read 536 times) previous topic - next topic

lboily

I've currently trying to build my own circuit that will trigger different audio and select audio channels. Currently the ground from the audio input is the only ground connected to the audio outputs. It does mute the audio channels, but not completely. If I try and connect the audio ground to the Arduino ground, the muting is more effective, but there is a lot of noise added to the audio. Any ideas how this could be done better?

Grumpy_Mike

Quote
Currently the ground from the audio input is the only ground connected to the audio outputs
In order for the transistors to switch correctly you need to connect the audio ground to the Arduino ground. Or the transistors need to be the output transistor of an opto isolator.

What is the diode doing in the base of the transistor? It only stops the transistor from turning on fully.

DVDdoug

I think you'd do better with an analog switch chip or relays.

I assume these are line level signals?

Are you trying to mute by shorting-out the signal?   That's not a good idea unless you know it's OK to short the circuit/device that's providing the signal.

MarkT

This is a job for dual-supply analog switch chips or signal relays. 
For instance MAX349/MAX350 are analog multiplexers with shift-register controls (like a 74HC595) and
handle dual supply for +/-5V analog signal swing, and are available in DIP.

Small signal relays will be more expensive, but avoids need for bipolar supply and is completely isolated which is probably a good thing from the point of view of hum pickup etc.
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