Ethernet Over Telephone Lines (or Whatever Cable)

I can hear the voices saying:

Hey buster we have internet over telephone lines and its called ADSL (or VDSL).

Thats true. Thats very true.

But have you ever considered how much a VDSLam costs? Totally out of the hobby budget. At least my hobby budget that is. So shouldnt be other ways around to transfer internet, apart from laying ethernet cables?

Oh yes and we call it WiFi. But as wifi is implemented for more than a decade, people have discovered that it has its own problems. Poor reception, noise signals from all over the neibhourhood, highly variable throughput that has to do with sitting this or that way on the couch.

I have to admit laying ethernet cables is the best way to transfer ethernet. But its not always convenient. I live in an apartment house and even though I have 4-5 ethernet cables going around, I cant really reach my neighbour and share my network with her.

So we tried this other solution called Homeplug or Ethernet over Power. This is essentially a very nice solution of transferring ethernet through power cables (110V - 220V). And it works. Sort of. The problem is power cables are very noisy, specially if your fridge or other motors work, and to be truthful we didnt like the idea that we wont have a connection every time I put the washing machine. And for our purpose (transfering network through different apartments) it was nearly impossible due to the circuit breakers. It worked but the speeds where slow and the noise from the cables interrupted the connection every few hours.

So I thought there are those other cables that go around the apartments. Yes the telephone cables. If you are lucky enough so that the telephone cables are twisted CAT3 or CAT5 then you can transfer internet directly (you need 2 pairs). I have succeded to reach 20-30 meters with old CAT3 cable. But my telephone cables are the old type, not twisted not anything because the building is old.

The problem is there is no ready made solution for telephone cables thats affordable (yep no point in being a rich hacker). So I thought if the Homeplug goes through noisy power lines, it should be a piece of cake going through telephone cables. And somebody somewhere would have done it.

Well only one part of the equation is true here. Yes homeplug protocol can work through telephone lines, but actually I have found only this one and even though inspiring, I didnt feel comfortable of feeding 110V on my telephone cables. Its not that they dont stand it. Telephone cables regularly have at least 50V on them, but I wouldnt like to shock the unsuspecting technician who will wonder around the switchboard box of your building.

Its kind of not cool, if not outright dangerous.

So my idea and this instructable, is how to hack a cheap 30-40 euro pair of Homeplug devices to deliver ethernet over the telephone line WITHOUT the 220V.

As I was searching for pictures on the net from different powerplug boards I found those people on openROV who actually did it too! So many kudos go over to the openROV people and they have lots of pictures of different boards.

Here it goes

words of warning . This is a very easy hack but you have to be somewhat confident around electronics and really careful around the 220V . We dont hack anything on the 220V side of the circuit, on the worst case scenario we just isolate the signal from the 220V.

So do this at home carefully, but if you are not confident invite a friend or your mother or anybody who is, for a coffee to help you out.

I hate those hypocritical don try this at home notices that then show an awful bunch of cool stuff that you really wnat to do at home. So just be careful and be respectful around the 220V , dont plug anything before triple checking, use a multimeter all the time and things will go fine :)

It doesnt matter much what generation they are. The fashion today is the 1000Μbits variety but this hack works with ANY kind of homeplug. My hack was done with an "old" pair of 200Mbits homeplugs. Anyhow like in wifi those numbers are purely theoretical (you wont get more than 60mbits from a 200mbit homplug).

The idea is simple. The homeplugs work by injecting the signal to the power line, so we would like to separate the signal BEFORE it is injected back into the 220V. That would render it safe.

Unfortunately every homplug device is a little bit different from the other so its not possible to say, go to jumper 2 and 3 and take the signal from there. I hacked a pair of devices from the same company and they both had a different layout on the board. Ok thats the bad news. The good news is that ALL homeplugs look more or less the same and the point you have to intervene is always the same.

So my job here is to give you guidelines of what to search for and where to find it.

Ok first step is open the homeplug device. Of course when its off power, right?

This can be a little bit of a pain in the ass because of those "security" screws. I have a set of security bits, but if you dont have one go on, break them. You can glue it back together with some hot glue afterwards.

There are two usual ways a homeplug device board is constructed. Usually It has two separate boards connected to each other via some jumpers. The boards are connected back to back more or less like an arduino shield. The one board is the 220V board (1 on the picture). you can tell that easily because its the one connected to the 220V, it has a couple of transformers etc. Be carefull with this one as it has 220V going around.

The other board is the electronics board (2 on the picture). This one is quite safe to play with as it usually has 3-12V going around.

As I told you the boards vary. Some new "tiny" ones have only one board with both 220V and electronics on the same piece of board. Thats more of a bummer but not much. If you look close, you will see that the board lines are electrically isolated between the two different sections. That means that on the board you will see the something close to the neutral zone on borders. A place on the board with no components and no lines on it.

From the two boards I hacked, as I told you I found two slightly different topologies which was a bummer for me, but a boon for you :)

the boards can look very complex but what you are really looking for is quite simple and straight forward. You are looking for the place where the ethernet signal gets injected back to the 220V. So actually the place where the signal gets back to the 220V part of the board. This is the small piece that looks like an inductor.

Actually it has 4 cables. Two going in from the electronic board and two going out to the 220V. This is the isolation part of the circuit as those pair of cables are not electrically connected. (so that the 220V dont reach the electronics)

As you see on the first picture things were quite easy. The isolation part was on the electronic board and the other end goes to those two jumpers that you see I already bended. So here you dont have to do no soldering or anything. You check with the multimeter if the two jumpers connect to the one end of the isolation part, you bend the jumpers so the dont connect anymore to the 220V board and thats it. Done you did it congrats.

Things though got a little bit more difficult on the second board I opened. The topology was the same. Two boards, one for electronics one for 220V. On the picture you see the 220V board, because someone thought its a good idea to put the isolator there. So here you have to desolder the 2 cables that go into the 220V (the left part of the isolator in the picture), and attach two cables yourself. Be VERY careful not to leave any exposed leads.

So essentially we are ready to test.

So now open 2 holes on the plastic so that your signal cables can pass through, assemble everything carefully and just connect them to the power.

Not tripping a fuse is the first successful test.

Second is to check with a multimeter the signal cables that you hacked. Well it goes without saying that they SHOULDNT show 220V AC :)

Then just connect the cables in between them, connect some ethernet cables on the homeplug devices and

VOILA you ve done it :)

Now experiment with something a little bit further away from the 2 meters you did the test with :)

Theoretically homeplug devices can go easily up to 300m cable, but your milage may vary.

Ours went from the second floor , to the basement where the tel switchboard is and then back up to the third floor where my friends appartment is . And it works like a charm :)

Some tips, and ideas

• The way we did the hack allows for power to be transfered upon the cables. Thats why we put our cables AFTER the isolation part. So actually you can have a functioning phone line (50V) and the homeplug device at the same time. I will try to also see if you can have adsl using a splitter, but thats for further research.

• On some boards (like the second one I hacked) its easier to take the cables BEFORE the isolation. Actually it would be as easy as on the first board, I just had to bend the two jumpers that connect the signal from the electronic to the power board. If you dont feel so confident desoldering cables that go to 220V, then just do it that way.

There is though one problem with that. As long as there is no isolation on the signal part, be sure that the cables you use have no power themselves. If they do, they may actually burn the electronic board.

• You dont actually need the 220V board per se. The electronic board works like a charm if you find the input lines (again jumpers that go from the power board to the electronic board) and feed them with power (some boards use 3.3V some up to 12V). So that means that you can have an internet connection to a remote station that works with batteries (lets say a lodge in the woods).

The reason I used the 220V board was just the convenience of supplying the powerplugs through their own supply.

So happy hacking , I hope I didnt make things too complicated for you (its my virgin instractable) , if you have questions just fire-away , I will check the comment section regularely

PS After some tests we made in real life, here are the results.

Type of Powerline adapters (200Mbps, nominal)

Max real speed in optimal conditions (70-80Mbps)

Connection: old copper telephone wires, monoclonal, not twisted

Distance: around 40-45meters total

Ping time 5-6ms!

Speed transfer (plus minus 8MB/sec or 60-65Mbps)

Im really impressed of how good and stably it works!

It is possible to get better speeds using a newer type of Powerline adapters like the 500Mbps or even the 1000Mbps, but I dont have one around to test :)