I would like to use this circuit to send a signal over the a live wire;
Assuming the live wire on the right carry the signal;
simulate this circuit – Schematic created using CircuitLab
This would work? The signal can be between 1 kHz to 12 kHz.
PS. I have an electrician background, installing and maintaining equipment on 127/220/380/440V, so I understand the safety issues. I'm careful.
This is going to take some work. The biggest problem is the 1 kHz is fairly close to 60 Hz, being only a factor of 16 different. A simple filter will (at best) reduce line frequency by a factor of 16 compared to your tone. So, if you inject 1 V rms into the power line, your received signal will (again, this is best case) have 1 V rms at 1 kHz, and (120/16) or 7.5 V rms at 60 Hz. Since your proposed input to a uC is presumably a simple digital 0/1, you're going to have a hard time detecting the smaller signal.
In EE terms, you need a good low-pass filter, and a single cap isn't going to cut it.
Furthermore, transistors don't work "from back to front" as you seem to think, so you can't just take the transmitter circuit and swap inputs and outputs as your figure seems to think.
You'll need to do some research, both on low-pass filters and on comparator circuits. There are lots of comparator ICs on the market, and you would feed the comparator input with the output of your selected low-pass filter, which would only pass frequencies above some frequency like 500 Hz.
We're not a design service, so I'll let you get to work.
I assume, that "reading" the signal works simplified very similar to sending it. I would try and decouple the two rails with a capacitor/highpass and amplify the noise (of which hopefully a good portion is the signal). Just make sure you filter all the frequencies you don't want.
