Coupling signals onto DC power lines

[jhendrix]

I have a system with a master and multiple slaves. I currently have separate power and communication wires. (I'm using cat 5 cables). I would like to only have 2 wires and run the communications on the power wires using FSK.

I'm thinking of pulling the signal off with a capacitor and then feeding it into an opamp.
What I'm having trouble is getting the signal on to the power lines. I've thought about using a transformer (like what's in a modem) to inductively couple the signal onto the power, but I'm having trouble designing a circuit to do this.

Any help would greatly be appreciated.

Thanks
Jeff

 

[dipnirvana]

I hope, i have understand properly.

Check in the figure i drawn for you. Connect your amplifier/transmiter to the side of C and DC wire in the end "C1".

The value of C and C1 will depend on the frequency of FSK signal . also , core of transformer will depend on the frequency , too[/img]

 

[jhendrix]

I just found a device that does what I'm looking for

https://www.sparkfun.com/commerce/product_info.php?products_id=9185

I'd like to design a simpler version of this circuit.