How can i send Audio+dc suply by 2 wires

[ataul]

hi friends

I want to make 3 station intercom connected every station by 2 wire all 3 station will have own circuit powered by central power supply and audio signal goes to each other by same wire. is it possible?

 

[dknguyen]

It's possible...whether or not it's worth it to try is another story. This is done sometimes with RF signals and power...the difference is that RF signals are always much much higher frequency than the DC power. Audio and the frequencies of DC power supplies overlap so the DC and audio are going to be interferring with each other. Audio is going to make you have lousy a lousy power supply and the DC noise is going to make your audio noisy.

 

[ataul]

Thanks dknguyen, i have try to send audio signal + dc to 20 feet distance but i am not satisfied, now i think my concept was wrong.

 

[q5101997]

The concept is good. Try this. Assume two transmitters/recievers for now. Simply add the audio to the DC supply through a capacitor for the transmittor. Then tap this off the DC at the receiver through another capacitor. 10µF should do.

 

[ataul]

I have create a diagram see it.

 

[dknguyen]

I have create a diagram see it.

THat is correct. You might want to stick inductors to filter the AC audio out from the DC Power supply (similar to how you use the caps to filter out the DC power supply from the AC audio) so the RX/TX get clean power. From your diagram it looks like the TX/RX are being powered directly by the PSU (no extra regulator or onboard circuitry to regulate and help clean the power), and if that is the case it could help your system work much better.

 

[Jules_Theone]

I've seen a transformer connected in series with the DC to transmit data over power lines, simply only the AC transmits through the transformer and depending on turns ratio the signal can be amplified. Also the audio is isolated from the DC.

 

[JimB]

I have create a diagram see it.

You need to decouple the power and signal.
A good PSU will kill any signals on its output due the the action of the decoupling and smoothing capacitors. Same for the power decoupling capacitors in the amplifiers.

Modify your diagram as I have shown below.

The chokes let the DC supply pass through, but block the audio signal.
The capacitors pass the audio signal but block the DC supply from entering the amplifiers.

JimB