To develop a cross-platform audio library, I need to switch between computers with different OS frequently to check if my code works on different platforms.
It’s annoying to unconnect the speaker from one computer and then connect it to another one again and again. Therefore, I made a device selector that can switch the audio source of the speaker by simply flipping a switch.
The circuit is super easy. It’s nothing more than a switch.
The above circuit diagram is for stereo(2-channels) speaker. If the speaker layout is 5.1(6-channels) or 7.1(8-channels), we need to replace the 9-pin switch to 21-pin or 27-pin switch.
In fact, the circuit is just a simple track selector, so it’s not only an audio source selector for a speaker, but also a speaker switcher for a computer. That is, you can either share one speaker with two computers, or share one computer with two speakers.
In general, it needs \((n + 1) * (k + 1)\) pins/wires to make a device selector for one n-channels output device with k (n-channels) input sources, or k output devices with n-channels and one (n-channels) input source. The first \(+1\) is for the ground wire, and the second \(+1\) is for the input or output device.