I've always wondered how they added a frequency to carry data or inject a 48v power line to power an arduino via ethernet.
But, what's the rules, i can inject as many AC frequencies providing it's different into an existing being used AC line?
for example, if i decided to power my house from a 22vac low voltage line around the home, what could you "inject" and how? diodes? timing?
cjdelphi:
But, what's the rules, i can inject as many AC frequencies providing it's different into an existing being used AC line?for example, if i decided to power my house from a 22vac low voltage line around the home, what could you "inject" and how? diodes? timing?
Isn't the "power" in Power-over-Ethernet DC?
Can i inject an AC signal into an existing AC line? eg a data line?
For injecting an RF carrier into mains wiring I'm not sure - there are a lot of different standards: Power-line communication - Wikipedia.
For power-over-ethernet the data signal is already balanced and transformer-coupled so you only have to replace certain centre-tap ground-connections with the power rail I believe - although for ether with spare pairs (100Mbit) power can also simply be wired through the spare pairs.
cjdelphi:
Can i inject an AC signal into an existing AC line? eg a data line?
Yes. The X-10 standard has been one method used for several decades for sending and receiving signalling information over a typical household AC power wiring to allow remote control of lighting and other consumer devices. Here is a pretty good write up on the method the standard uses and even gives example of interface circuitry that can be used. http://www.x10pro.com/pro/pdf/technote.pdf
Lefty
There's also an X 10 Library in the playground and the X 10 modems can be found on Ebay. I bought 3 for about $15.00 Ea.. In an hour, 2 for a project I'm working on and one spare. There are 2 types TW523/PSC06 duplex or TW513/PSC05 simplex. Lefty pointed put that there is an active forum that 'looks' OK with more than a few Arduino users... Too.
Bob