Fire Protection


For quite a while now I’ve had 2U at the top of the rack consumed by an APW Fire Protection Unit. This clever bit of kit, found by chance on eBay for £15, will extinguish a fire using FM200 gas (with some nitrogen thrown in) when detected by either of it’s two optical smoke detectors.


Until today it hasn’t been plugged in for more than half a second because the alarm appears to be broken inside (or I need to do some sort of configuration which isn’t possible without a manual) and so it was far too noisy to use. The alarm is deafening and certainly does it’s job, but is obviously a little eager to make itself known. Just in case this was an indication that the gas might be released I disconnected the fillament in glass stopper on the end of the canister (later reconnected when I was happy it’s only the alarm that is broken).
To solve the alarm problem I have been forced to snip one of the wires to the sounder so that I can use it. This shouldn’t affect the operation of the unit, though it wont be able to give any audible indication of a fire. There is a visual indicator on the front to back it up. To replace to the audible function I will install a standard household smoke alarm.


I’m just waiting for a backup to complete before I hand over power management to it. In the event of a fire, it will instantly cut power to anything that it feeds, which in this case will be most things that are connected to the UPS. Unfortunately the UPS shutdown functionality isn’t compatible with my UPS since it uses basic status signalling, so if a fire does break out it had best not be in the UPS.

Getting NUT working with a Compaq T2400h


Several months ago I posted some information on the cable to connect a Compaq T2400h to a standard serial port. This weekend I finally got around to trying out the information that I found. I now have the 2.4KVA UPS at the bottom of my rack cabinet talking to my Ubuntu-based fileserver, boron.

The first step was to create the cable. This requires a 9 pin female ‘D’ connector and a matching male connector. For the cable I used an offcut of CAT5, though normally serial cables do not use twisted pair (usually just parallel wires).





The software part is done using NUT, for which there is a package included in the Ubuntu distribution. This software talks to the UPS, monitors it’s status and allows other computers to check the status. The monitoring applications are then responsible for shutting down the computers attached to the UPS should power fail and the battery become critical. So far this is just boron and my Windows machine, aluminium. The latter uses WinNUT to shut down Windows when needed.

There were a few problems getting NUT to work with Ubuntu. First off, the package doesnt put any configuration files in the /etc/nut path, so I had to go hunt for the examples and copy then modify them. The next problem was with permissions for the serial port. For testing purposes I tried running the protocol module as root, but this introduced different permissions problems. The solution was to add the ‘nut’ user to the ‘dialout’ group, which is one group that has access to the serial ports. To my relief this got everything working.

These are the parameters that I can access over the serial connection:

simon@boron:~$ upsc compaq@boron
battery.charge: 97.22
battery.runtime: 1620.000
battery.voltage: 0055.50
battery.voltage.nominal: 0048.00 upscode2
driver.parameter.input_timeout: 5
driver.parameter.manufacturer: Compaq
driver.parameter.port: /dev/ttyS0
driver.parameter.use_pre_lf: yes
driver.version: 2.0.5
driver.version.internal: 0.84
input.voltage: 0244.50
input.voltage.maximum: 0276.00
input.voltage.minimim: 0162.00
input.voltage.nominal: 0230.00
output.current: 0001.95
output.frequency: 0050.00
output.voltage: 0215.10
ups.delay.reboot: 000
ups.delay.shutdown: 000
ups.load: 21.875
ups.mfr: Compaq
ups.model: UPS 2400 VA FW -0023
ups.power.nominal: 2300.000
ups.serial: E########
ups.status: OL TRIM

These are the resources that I used to get the UPS/NUT combo working:

iPod remote control interface mockups

Here are some initial interface wireframes for the iPod Touch remote control. I’ve not shown all of the menus because that would be quite a bit of work. These three should give you an idea of what I intend to do though.

Main menu

The main menu summarises the major systems of the house. Clicking on one of the buttons takes you to more controls for that system. The colour of the buttons indicate the overall state of the system – green = OK, yellow = warning, red = error, grey = disabled.



The audio controls will list the 4 zones, with a drop-down menu next to each button to select the audio source. Clicking the large button switches the zone on or off. Pressing the ‘Use for all’ button copies the settings of the selected zone to all the other zones.



The large buttons display a thumbnail of the live video from the cameras. Clicking on the large button will show the full video feed (resized to fit the iPod’s screen). Cameras can be disabled for privacy.


Sensor boxes

Whilst pondering over what sensors I could put around the house, I ventured upon the idea of having a ‘sensor box’ per room. This would be based upon something like the Netiom xAP, which would connect various sensors to the house’s IP network. Some of the sensors in each room would be different. Here are some examples of the sensors that would be common to all of the rooms:

  • Temperature
  • PIR (motion detector)
  • Door contact
  • Window contacts
  • Light

Room specific sensors could be:

Entrance hall:

  • Current meter
  • Intruder alarm status (triggered/armed)
  • Door bell


  • Back door bolt contact
  • Oven/hob state

Each of these nodes can then be queried, via the xAP protocol in this case. Temperature could be recorded, although at present our combi-boiler would probably not allow for remote control. Motion detection and door contacts can be used to determine which rooms are occupied, and along with the window sensors could be used as a secondary security system. The light sensors would be used to control the house lights.

Having one single ‘node’ to talk to would do away with having lots of independent sensors that would probably all communicate differently. Thanks to having picture rail throughout most of the house, there won’t be a problem with hiding the wiring. I’m not sure how big the boxes would be, but I dont think they would be massive. I just need to find the money to build a prototype.

Conserving energy in an automated home

In the same way that the saying “you’ve got to spend money to make money” works, sometimes it’s also necessary to spend energy to save energy. An automated home may have more gadgetry than normal homes, but if set up correctly these little power-consumers can help to save energy. While the debate about whether the apparent global warming trend is the result of our actions, it can’t hurt to try to reduce energy use (or rather, conversion) as much as possible.

Continue reading “Conserving energy in an automated home”

Wiring the house


Before we moved into our new house, I lifted some of the carpets and floorboards and installed some runs of cat5 and speaker cable. In total there are 24 cat5 cables and 4 pairs of speaker cable. I’m not sure the length of network cable that was used, but a rough estimate is 400m – not quite as impressive as some other installations I’ve seen details of, but it’s a fair amount to pull on your own! I know exactly how much speaker cable was used though, because I used the whole reel – 100m.

Continue reading “Wiring the house”

Project Names

I have currently have a two different naming schemes in use, to identify my various computers and networks. My home network is called ‘elemental’, and each node attached to the network that has an IP has a name taken from the periodic table of elements. The computer I’m typing this on at the moment is called ‘aluminium’ … because it’s got an alumimium case. My external severs are under the ‘sol’ network, which currently only has one node called ‘earth’.

Now I’ve had the idea of naming my various projects. I just need to come up with a naming scheme. Maybe subatomic particles? There are enough of those to keep me going for a while, especially once CERN get the LHC (what a lovely retro site) experiment running. Let’s try that:

  • Project Electron – The rack cabinet (contains most of the other projects)
  • Project Gluon – Cat5 wiring (holds stuff together, in a network sense)
  • Project Quark – Audio distribution system (Quark in DS9 is a Ferrenghi … has big ears … can hear well …)
  • Project Proton – Security & surveilance (can’t think of an excuse)
  • Project Neutron – MythTV install

Of course, unless I’m going to name things after various versions of some of the particles (up quark, down quark etc.), it is actually quite limited for the time being. And not being a physicist (beyond A-level) doesnt help.

I can’t think of any other schemes at the moment.

Hmm, this has turned into quite a monologue. I think I’ll shelve the idea for the time being, unless someone can come up with better suggestions.

My DIY 19″ Rack

The (almost) completed rackThis project started off as being a cheap way to have a 19″ rack in which to mount my growing amount of equipment and future projects. It turned out to not be as cheap as I’d hoped, and it’s taken several months of intermittent work to (almost) complete, but I’m pleased with the results.

There are still a few finishing touches to be done, such as adding the top, adding the lock to the rear, mounting the new bolts to the front door, cutting out the bottom ventilation hole and adding some fans. Future modifications could include adding lighting and environmental monitoring/control.

Below is a photo log showing how it was done.

Continue reading “My DIY 19″ Rack”