FM over AC power line

[DJ_ReL@X!]

Hi, does anybody know a cheap and easy way to transmit FM signals over the AC power line? :shock:

 

[JimB]

Yes, but it is certainly illegal in the UK (and the rest of Europe).

For a start it is banned by the EMC regulations.

JimB

 

[DJ_ReL@X!]

In Mexico, where i am, it's not illegal. It's only a tiny project. I would need no more than 10 meters from Tx to Rx. I'm using LM565's for modulation and demodulation. AC power line is 127 V @ 60 Hz :roll:

 

[JimB]

I had a quick look at the LM565 data sheet and the maximum operating frequency is about 500kHz.

What you need is a high-pass filter which will present a low impedance path to your 500khz signal, but a high impedance to the 60hz mains.

Other things to consider:

Any wideband noise on the mains will interfere with your signal and you will get a high error rate or it wont work at all.

Safety. You need to consider the components connecting the circuit to the mains, they need to be rated for mains voltage and provide reliable isolation. An HF transformer would be a very good idea.

Must you use the mains? Is it not possible to run a separate cable?

JimB

 

[DJ_ReL@X!]

What you need is a high-pass filter...

Any wideband noise on the mains will interfere with your signal...

You need to consider the components connecting the circuit to the mains, they need to be rated for mains voltage and provide reliable isolation. An HF transformer would be a very good idea.

Must you use the mains? Is it not possible to run a separate cable?
JimB

Would it work if i make air core transformers to provide isolation and filtering with a series capacitor (rated 250 V)?

I must use the "mains". The circuit won't be used actually to transmit information. I'm going to show it working once with some signal. That's all.

I don't know what to do if wideband noise is present.

 

[williB]

google .. Circuit cellar...
they were working on a HCS home control system.. that used transmission of info over the powerline...
maybe you could convert the interface to fit your needs...