I need to send an audio signal over 3 meters and back again on the same line (the plan is to put an on/off switch and a volume regulator at the end of the line).
Additionally I would like to send 12 volts power in the same cable, with small amperage.
Is it possible to use an Cat5 Ethernet cable for that purpose? I have those in abundance, and want to avoid buying a dedicated cable for that purpose.
I would use following signals:
- Audio Right In
- Audio Left In
- Audio Ground In
- Audio Right Out
- Audio Left Out
- Audio Ground Out
- 12 V +
- 12 V –
I think a good question to ask here is: what kind of audio signal?
If you can spare e.g. an Opamp per channel and end, plus the power for that, and a terminating relatively low resistor (e.g. 120 Ω, 47Ω, or even less), then you'd waste power, but you'd get a very stable transmission.
Don't do that – your twisted pair cable is meant for differential pairs. So, instead of transmitting ground (which is just a recipe for all kinds of avoidable hum and DC currents), convert your single-ended audio on the transmitting side into a differential one, and transfer that on a twisted pair (blue / blue-white, and so on):
Converting from single-ended to differential can be done using inverting op-amp circuitry, or opamps with differential output, or dedicated differential line driver ICs, or signal transformers.
Nah. Ethernet cable's not a good conductor of current, so you'd avoid this.
Also, if you use a signal transformer on the end, you can just use the center tap to impose DC over your differential audio signal, and can avoid having dedicated power pairs. That's how Power-over-Ethernet works!