Mar 232018

So last week, I came home to no power, which of course meant no Internet because the ADSL service is still on mains power.

This is something that’s been on my TO-DO list for a while now, and I’ve been considering how to go about it.

One way was to run 12V from the server rack to the study where the ADSL is. I’d power the study switch (a Cisco SG-208), the ADSL modem/router (a TP-Link TD-8817) and the border router (an Advantech UNO-1150G).

The border router, being a proper industrial PC is happy with any voltage between 9 and 32V, but will want up to 24W, so there’s 2A. The ADSL modem needs 5V 1A… easy enough, and the switch needs 12V, not sure what power rating. I’m not sure if it’ll take 15V, I’d be more comfortable putting it on an LDO like I did for the Linksys switch and the cluster nodes. (Thanks to @K.C. Lee for the suggestion on those LDOs.)

With all that, we’re looking at 3-4A of current at 12V, over a distance of about 5 metres. The 6 AWG cable I used to hook panels to solar controller is obviously massive overkill here, but CAT5e is not going to cut it… it needs to be something around the realm of 12 AWG… 20 at the smallest.

I have some ~14AWG speaker cable that could do it, but that sounds nasty.

The other approach is to move the ADSL. After finding a CAT3 6P4C keystone insert, I dug out some CAT5e (from a box that literally fell off the back of a truck), slapped my headlamp onto my hard hat, plonked that on my head and got to work.

It took me about an hour to install the new cable. I started by leaving the network-end unterminated, but with enough loose cable to make the distance… worked my way back to the socket location, cut my cable to length, fitted the keystone insert, then went back to the ADSL splitter and terminated the new run.

There was a momentary blip on the ADSL (or maybe that was co-incidence), then all was good.

After confirming I still had ADSL on the old socket, I shut down the router and ADSL modem, and re-located those to sit on top of the rack. Rather than cut new cables, I just grabbed a power board and plugged that in behind the rack, and plugged the router and modem into it. I rummaged around and found a suitably long telephone cable (with 6P6C terminations), and plugged that in. Lo and behold, after a minute or two, I had Internet.

The ugly bit though is that the keystone insert didn’t fit the panel I had, so for now, it’s just dangling in the air. No, not happy about that, but for now, it’ll do. At worst, it only has to last another 3 years before we’ll be ripping it out for the NBN.

The other 3 pairs on that CAT5e are spare.  If I want a 56kbps PSTN modem port, I can wire up one of those to the voice side of the ADSL splitter and terminate it here.

I think tomorrow, I’ll make up a lead that can power the border router directly from the battery.  I have two of these “LM2596HV” DC-DC converter modules.  I’m thinking put an assortment of capacitors (a few beefy electrolytics and some ceramics) to smooth out the DC output, and I can rummage around for a plug that fits the ADSL modem/router and adjust the supply for 5V.  I’ll daisy-chain this off the supply for the border router.

We’re slated for Hybrid Fibre Coax for NBN, when that finally arrives.  I’ll admit I am nowhere near as keen as I was on optic fibre.  Largely because the coax isn’t anywhere near as future-proofed, plus in the event of a lightning strike hitting the ground, optic fibre does not conduct said lightning strike into your equipment; anything metallic, will.

By moving the ADSL to here though, switching to the NBN in the next 12-24 months should be dead easy.  We just need to run it from the junction box outside, nailing it to the joists under the floor boards in our garage through to where the rack is.  No ceiling/wall cavities or confined spaces to worry about.  If the NBN modem needs a different voltage or connector, we just give that DC-DC converter a tweak and replace the output cable to suit.

We of course wait before switching the DC supply until after we’ve proven it working from mains power in the presence of the installer.  Keep the original PSU handy and intact for “debugging” purposes. 😉

There is an existing Foxtel cable, from the days when Foxtel was an analogue service, and I remember the ol’e tug-o-war the installer had with that cable.  It is installed in the lounge room, which is an utterly useless location for the socket, and given the abuse the cable suffered (a few channels were a bit marginal after install), I have no faith in it for an Internet connection.  Thus, a new cable would be best.  I’ll worry about that when the time comes.

On the power supply front… I have my replacement.  The big hold-up with installing it though is I’ll need to get a suicide lead wired up to the mains end, then I need to figure out some way to protect that from accidental contact.  There’s a little clear plastic cover that slips over the contacts, but it is minimal at best.

I’m thinking a 3D printed or molded two-part cover, one part which is glued to the terminal block and provides the anchor point for the second part which can house a grommet and screw into the first block.  That will make the mains end pretty much as idiot-resistant as it’s possible to be.  We’ll give that some thought over the weekend.

The other end, is 15V at most, I’m not nearly so worried about that, as it won’t kill you unless you do something incredibly stupid.