So I hooked up the spare drive, got Windows 7 installed, played around for a little while then got bored with it.

Reverting my computer back to its normal configuration was easy. Just remove the spare drive and re-connect the old ones. So I did that, and powered back up and glanced at the side of my perforated case. ‘Funny’, I thought, ‘I don’t remember having an amber LED inside the computer… and what’s that sound? Cables hitting a fan?’. Then came the smell. ‘F^&*ck!!’

After the reflex move of yanking the power cord, I removed the side of the case and extracted one of the drives to find the scene below.

I think there may be a flaw in the design of the SATA power connector, which means that if it’s slightly dislodged then the 5v rail and ground can short out quite spectacularly. And when you have a high-power PSU, the over-current cut-out threshold is set too high so there’s no protection from things like this.

The drive which was damaged is part of a RAID 0 array, meaning that half of the data of my running system was on it. I have 2 independent methods of backup for my main computer: daily file backups of all important files (photos, source code, documents etc.) and a manual perdiodic backup using Norton Ghost. If the worst came to the worst, I should eventually be able to recover all my important stuff and theoretically a complete system image. However, last time I tried to restore from Ghost, the result was very unreliable and had to be dumped.

So, before I considered going down the route of backup restores I thought I’d have a go at repairing the drive.

It looked like only the board had become damaged, and at that only the connector and nearby soldering (the copper tracks had melted into balls) was affected. Ebay is your friend when it comes to finding rare parts, so I started there. I needed an exact match to the drive that I was trying to repair, since I needed a controller board which would work with the internal drive mechanics which should still be working fine.

The first order was a disappointment. The listing was slightly misleading, as it listed the exact model I wanted but the model I received was an equal size but completely different configuration.

The second order wasn’t as bad, but didn’t work. It was manufactured at a different plant, and used slightly different chips and a different firmware version. Although the drive spun up, none of the computers I tried it with would recognise it at all.

2nd replacement drive - didn't work

After wasting a chunk of money, I looked at the corner of my desk and whaddya know … an excact matching drive! Lesson: look around for things hiding in plain sight before wasting money. The matching drive was originally paired with the damaged one, but got replaced when it sounded like it was dying (turned out to be something else).

The identical drives which provided the solution

So, swapping the board from the twin drive to the broken one solved the problem. 2 weeks later I had a working machine again.

I normally only have the one machine on constantly, my server boron. It’s a fairly old self-built P4 with an old Radeon 9600 AGP graphics card, which puts out more heat than most of my newer machines. When idling, there’s enough heat to keep the cabinet at a mild temperature on these cold nights, but the room is not so easily heated. In summer, there is the opposite problem of too much warmth which on really hot days can only be solved with air conditioning.

With a temperature sensor or two, I could set up boron to run a CPU-intensive task (such as a BOINC project like Folding@Home or Seti@Home) when it’s cold to produce heat while at the same time doing something useful. While it’s not an efficient way of heating a room, you gain both heat AND processed data, rather than just producing heat and nothing else like an electric heater would.

If I had more (quiet) computers in my room, I could keep them off most of the time, then turn them on automatically (using Wake-on-LAN, for example) when heat is needed to do some number crunching.

This idea could be applied to an entire house, like my future self-built house (still in the dream stage, and probably will be for at least 15 years). The heat produced by computation could be put to use heating a house in winter, directly using the warm air, or just helping to heat hot water in the summer by using a heat exchanger to pre-heat the water going into the boiler.

In fact the same could be, and probably is, applied on a commercial scale in newly designed efficient corporate buildings, where the heat from server rooms and networking closets is used to improve the efficiency of heating and hot water provision. Many new well-designed buildings take into account natural air flow, attempting to minimise the amount of energy required for environmental control. Such a use of the inefficiency of necessary electronic systems would add to this eco-design.

Back in the present, in my current location, using the machines I have, this could be accomplished quite easily by setting up a computer-connected thermistor measuring the ambient room temperature and some simple software to monitor the temperature and start/stop intensive tasks as necessary. Not difficult or expensive at all. It could also be applied to the MythTV box, sodium, downstairs in one of the coldest rooms of the house.

If you know of anyone or any buildings that use something like this, I’d be interested to hear about them. Please add a comment below if you are aware of any instances of this idea in use.

A few months ago we were given a couple of old laptops by some relatives. I cleaned both of them up, gave one a fresh install of XP Home and the other Ubuntu. The former has now become the family PC and the latter is sitting on top of some draws in my room unused because the power supply connector is nearly unusable.

Being the lazy person I am, wanting to be able to watch TV and surf from the comfort of my bed, I decided I needed a laptop that actually works. When someone on the UKHA mailing list pointed to an offer on Amazon for an Acer Aspire One L150 (white) for £199, I decided I had to go for it. I wasn’t too keen on the white netbook though, so I paid a little more for a lovely blue number.

It came well packaged in a nice compact box. I was at work when it arrived, and didn’t have much time to play with it, but I powered it on and filled in the details it requested on first boot. After that I had a brief play with the interface.

The specially designed RedHat linux-based UI is very friendly for a novice user, categorising everything into 4 groups. I used it for a few hours at home, eventually realising that while the interface is perfect for a normal person, power users who want to do more than just web surfing, checking emails, writing documents or playing solitair are stuck. There is no option to install extra software and no (easy) way to get a console window up.

Ubuntu to the rescue! I got out my USB DVD-RW drive and installed the only version I had at the time (8.04), with mixed results. Hardware support on that version was very flakey, and when I tried to upgrade to 8.10 through the Update Manager it died completely. On my second attempt I downloaded the ISO for 8.10 and installed again. After some tweaks it was working nicely, or at least the important stuff was (screen, keyboard, touchpad, wireless, ethernet). The webcam also works, thanks to V4L. I’ve not bothered testing the microphone, but I know the SD card readers don’t work. I don’t plan on using them anyway, and if I do need to then I can just boot into the original OS which is still stored in a (shrunken) partition.

The performance is surprisingly good. It’s just fast enough to run a MythTV frontend, meaning I can watch recordings or live TV without turning my TV & attached MythTV box on. The onboard graphics card even copes with the special window manager effects included in Ubuntu. Web browsing is reasonably smooth.

I have ended up buying a wireless mouse because the touchpad is very fiddly when browsing. The keyboard is just smaller than a normal laptop keyboard, which takes a little getting used to but it’s still quite quick to type.

Battery time is nowhere near the 3 hours claimed on Amazon. Ubuntu estimates it at 1 hr 55 mins from a full charge, although it seems a little less than that when I’ve tried running it completely disconnected. Wireless probably zaps a good bit of power, but if you don’t have a power supply to hand then it’s unlikely you’re going to have an ethernet cable to hand either, so most of the time wireless needs to be on while on battery power. An extended life battery can be purchased for about £50, which I’m guessing would give a real world runtime of about 3 hours. If I find myself using this netbook a lot then I might buy one.

All in all it’s a nice little computer. Build quality is very good, as is the performance. I would recommend it to anyone who’s looking for a light-weight netbook to do light tasks (i.e. don’t plan on playing Left 4 Dead on it).

The CurrentCost power monitor has become very popular amongst amateur home automators and those technically-savvy who want to keep an eye on how much electricity they are using (and ultimately how much they are going to have to pay in bills). A couple of months ago I purchased the CurrentCost device and a USB cable to connect it to a computer from eBay. Having just seen their eBay store, it looks like they’ve got a fantastic new model on the way, but this article is about the older version.

By itself the device works very well, providing an at-a-glance view of current power use and a history over several periods of time. There is a simple bar chart showing the relative amounts of power used in the previous day, split into day time, evening and night. However if you want a clearer understanding of how power use changes day-to-day or even over a decade, connecting the device to a computer will provide the ability to store every reading in a database and/or produce live graphs of usage.

Several people have written articles on how to do the logging, each using a slightly different method (and language) to do so. Most of them are for linux though, but any programmer should be able to port the ideas across to a different platform such as Windows or Mac OS. For my implementation, I followed this guide on jibble.org.

This is what my perl script turned out like:

#!/usr/bin/perl -w
# Reads data from a Current Cost device via serial port.

use strict;
use Device::SerialPort qw(  ARAM :STAT 0.07 );

my $PORT = "/dev/ttyUSB1";
my $ob = Device::SerialPort->new($PORT);

$ob->baudrate(9600);
$ob->write_settings;

open(SERIAL, "+>$PORT");
while (my $line = <SERIAL>) {
    if ($line =~ m!<ch1><watts>0*(\d+)</watts></ch1>.*<tmpr>([\d.]+)</tmpr>!) {
        my $watts = $1;
        my $temp = $2;
        print `/usr/bin/rrdtool update /var/scripts/currentcost/powertemp.rrd N:$watts:$temp`
    }
}

Note that because I’m connecting via a USB port, the serial port name is different. The baud is also 9600 rather than 2800. I have set this script to run at startup (detatched from the console) so that it is always running in the background.

I have also produced another simple script, which is run every minute as a cron job.  The script generates the graphs from the data stored in the RRD file, and uploads them to my web server via SSH.

#!/bin/sh

rrdtool graph /var/scripts/currentcost/power-10min.png --start end-10m --width 323 --end now --slope-mode --no-legend --vertical-label Watts --lower-limit 0 --alt-autoscale-max DEF:Power=/var/scripts/currentcost/powertemp.rrd:Power:AVERAGE LINE1:Power#0000FF:"Average" > /dev/null
rrdtool graph /var/scripts/currentcost/power-60min.png --start end-60m --width 323 --end now --slope-mode --no-legend --vertical-label Watts --lower-limit 0 --alt-autoscale-max DEF:Power=/var/scripts/currentcost/powertemp.rrd:Power:AVERAGE LINE1:Power#0000FF:"Average" > /dev/null
rrdtool graph /var/scripts/currentcost/power-day.png --start end-24h --width 323 --end now --slope-mode --no-legend --vertical-label Watts --lower-limit 0 --alt-autoscale-max DEF:Power=/var/scripts/currentcost/powertemp.rrd:Power:AVERAGE LINE1:Power#0000FF:"Average" > /dev/null
rrdtool graph /var/scripts/currentcost/power-week.png --start end-1weeks --width 323 --end now --slope-mode --no-legend --vertical-label Watts --lower-limit 0 --alt-autoscale-max DEF:Power=/var/scripts/currentcost/powertemp.rrd:Power:AVERAGE LINE1:Power#0000FF:"Average" > /dev/null
rrdtool graph /var/scripts/currentcost/power-month.png --start end-1months --width 323 --end now --slope-mode --no-legend --vertical-label Watts --lower-limit 0 --alt-autoscale-max DEF:Power=/var/scripts/currentcost/powertemp.rrd:Power:AVERAGE LINE1:Power#0000FF:"Average" > /dev/null
rrdtool graph /var/scripts/currentcost/power-year.png --start end-1years --width 323 --end now --slope-mode --no-legend --vertical-label Watts --lower-limit 0 --alt-autoscale-max DEF:Power=/var/scripts/currentcost/powertemp.rrd:Power:AVERAGE LINE1:Power#0000FF:"Average" > /dev/null

#Copy locally
cp /var/scripts/currentcost/*.png /var/www/currentcost/

#Upload to mars
/usr/bin/scp /var/scripts/currentcost/*.png root@192.168.2.3:/var/www/vhosts/currentcost.elemental.killswtch.net

You can see the result on the Power page of this site. The graphs at the moment are fairly basic. The Jibble article includes some extra data in the graphs, which I will probably add at some point. For the moment though it does the job very well.

The CC device is located downstairs, in the living room. Thanks to the serial output connector being an RJ45 socket, it was very easy to plug it into the exising CAT5 network (which I’m very glad I did) and run the signal to the cabinet in my room where it is then broken out through the RJ45 patch panel, through the RS232/USB cable and into the fileserver boron, which hosts the scripts.

Over a year after it began, the whole-house-audio project is complete. 4 rooms around the house can now be filled with the sound of any of (currently) 4 audio devices thanks to a mixture of hardware and software.

The project had a slightly rocky start, with a prototype not functioning at all and partly destroyed amplifier (which was thankfully fixable by replacing a couple of components). A software alternative was considered at one point, to avoid too much expensive hardware. The hardware solution proved to be less complex and more likely to work.

The living room, dining room, kitchen and master bedroom are host to a pair of speakers each, connected to matching 240W rack-mounted amplifiers housed in my home-made full-height 19″ rack cabinet. The cables that carry the audio signals to the speakers were installed along with 24 runs of CAT5 before moving into the house.

The audio is routed to the amplifiers via an 8×8 VAMS-0808 AV matrix switcher, which allows the 8 outputs to take their inputs from any of the 8 available sources. Only 4 of each are currently in use, so there’s plenty of room for expansion.

4 audio sources are connected via simple custom-altered CAT5 cables, which simply transmit line-level signals over the existing twisted pair infrastructure installed in the house. These sources are currently the DAB radio in the kitchen, the TV in the living room, the computer in the dining room (for playing CDs) and a second DAB radio in the master bedroom.

I’ve written the software to control it all using .Net (C# of course), running on mono on linux. There are four components to this:

1. To control the matrix switcher, I have written a library which communicates with the VAMS-0808 via an RS232 serial connection. The software can perform any of the operations that can be performed via the front panel of the device, apart from switching power on and off.
2. The amplifiers are connected to an APC AP9212 MasterSwitch Power Distribution Unit which was bought with this project in mind. Controlling this is slightly less straightforward and not quite as elegant. The library that I’ve written for this communicates through the telnet interface of the MasterSwitch to turn devices on and off.
3. Combining these two libraries is a simple web server which presents an equally simple XML-based web service. The service allows room inputs to be changed and switches the amplifiers on and off as necessary. This runs on a low-power disk-less computer running Ubuntu, hidden within the rack cabinet.
4. A touchscreen web interface acts as a front-end to the entire system. The simple menu system uses iUi for a clean touchscreen-friendly design. As with the web server this runs on a low-power machine, although this one has a small hard disk and runs Windows due to technical issues with the touchscreen.

There is currently just the one controller front-end, located in the dining room. To listen to the kitchen radio, for example, all that is necessary is to select the ‘Kitchen DAB Radio’ option from the main menu, then select which of the 4 rooms to play it through – or all of them if you are going to be wondering around most of the house.

Future extensions

Thanks to building the web interface with iUi, the system is compatible with the iPod Touch and iPhone, so they can instantly act as frontends for audio control. A second fixed controller may be added in the master bedroom in time, if there’s enough money available. Each front-end costs about £200 in hardware, depending on what bargains can be found on eBay.

The matrix switcher supports both audio and video. Only the audio channels are used at the moment, so there is the very real possibility of using the remaining 4 output zones to connect to TVs around the house and adding some AV sources. This way it’s instantly converted into a whole-house-AV system. The video signals can be carried over the twisted pair CAT5 cables like the audio, but will require a little more hardware to preserve quality. This hardware is relatively expensive, although savings can be made by building the equivalents by hand. Following the tradition of this project, that’s probably what I’ll do. I have done it before while I was at university and it works beautifully.

One thing that has been lacking since the first build of the rack is ventilation. With both sets of doors closed, the inside can get quite warm, especially when iron is turned on. Not any more though, having just completed the installation of 2 active ventilation zones, lighting and a low voltage power supply system complete with rack-mount control panel.

Air is drawn in at the bottom of the rack by 5 quiet 80mm 12v fans, positioned behind a perforated 2U panel inside the front panel of the base. The air is blown vertically into the cabinet from the bottom through a similar 1U perforated panel. Although the draught is barely noticeable, the difference it makes to temperatures at the front of the rack is significant.

With this ‘air curtain’ alone though, the back of the rack still gets very warm. To solve this I’ve installed a relatively huge 200mm ‘Big Boy’ fan into the newly-added top of the cabinet. This sucks out the warm air and dispenses it into the containing room. Together these fans keep the entire cabinet cool.

To power the fans I’ve used an old ATX power supply. In order to make replacement easy when the supply fails, no modifications have been made to it. Instead, I bought a 20-pin molex connector so that I could just plug the ATX connector straight into my system.

The PSU is connected to 4 switches that are mounted on a 1U blanking panel in the front of the rack. I wanted some fancy switches, so I splashed out on some nice chromed illuminated ones from China (via eBay). There’s one green DPDT switch, which switches the PSU on and off, and three blue SPDT switches which control power to the two fan systems and some lighting.

The lighting illuminates the front of the rack, and is there purely for decorative purposes. I had considered using cold-cathode tubes, but the seller that I got the switches from also sells strips of LEDs encased in a flexible transparent rubber-like substance. They are sold in various lengths, but I thought 96cm would be OK for what I wanted (at the time I bought it to experiment with, thinking that it could illuminate the wall behind my desk). This strip is now mounted on the left-hand front door.

The audio system that I’m building requires 2 low-power computers: 1 for the touchscreen controller (not using an iPod Touch for the moment) and 1 to act as a webserver and serial-console server.

Once again eBay has come to the rescue, and by searching for ‘geode’ – a low-power processor for Thin Clients & Small Form Factor (SFF) PCs – I found the 2 machines that I needed. These are the specs:

magnesium (the black one)

• 800 MHz Geode
• 256 MB RAM
• 6 GB CF drive
• Onboard graphics, audio, serial, parallel, USB & 10/100 ethernet

£70 + P&P

potassium (the grey one)

• 300 MHz Geode
• 256 MB RAM
• 6 GB 2.5″ IDE drive
• Onboard graphics, audio, serial x2, parallel, USB & 10/100 ethernet

£35 + P&P

Magnesium is used as the client machine, and potassium runs a custom-made webserver and the control software for the VAMS-0808 Matrix Switcher.

Both came pre-installed with Puppy Linux, a lightweight distribution designed for low-power machines such as these. It runs surprisingly quickly, but to make it easier for me to maintain I decided to install Ubuntu.

On such slow computers it took many hours to get Ubuntu installed on magnesium alone. I initially installed to the CF drive that came with the machine. However I found it to be quite slow, so I followed a guide for running Ubuntu via network boot and removed the CF disk. I did the same for potassium. Both booted off of the fileserver, boron.

Unfortunately during installation, I found that the slower of the machines has a tendancy to overheat causing the machine to hang. To get Ubuntu installed I had to remove the case. This has now been rectified by installing a blower to get at least some air circulating. This is the only fan in either of the machines. Magnesium gets quite hot but has never crashed because of it. It also sits in a cooler environment, and is much better engineered.

Sadly I’ve been forced to install Windows XP on magnesium purely because I couldn’t get the touchscreen to work under linux despite spending more than a day trying to. While it was detected, and it detected touches, the calibration was completely off and there was no way to configure it. Rather than waste any more time I decided to switch to Windows and everything has worked beautifuly since then. To accomplish this I’ve had to reinstall the CF disk since as far as I know XP Pro can’t do diskless booting.

Shots of these computers in use and more information on their roles to come soon.

One of the things that has been lacking in my bedroom is a TV. I can watch recorded TV programs, DVDs and other videos on my PC, but not at the same time as relaxing on my bed. While I had a week off work I was looking around the Dabs website and ventured across a real bargain of a TV (now discontinued). It supports full 1080p HDTV as well as being a relatively huge 37″ all for just £539. I couldn’t pass this by, so I spent a while doing investigation work and finally decided to take the plunge and buy the thoroughly indulgent item.

When I designed the rack, the idea was that I would eventually get an LCD TV and it would be mounted to the side of the rack. However, it now contains so much equipment that the weight has become a bit of a concern. To avoid problems with the rack castors collapsing under the load – or even the floor of my bedroom doing the same – I decided to mount it in a more traditional location, on the wall at the foot of my bed (though I had to turn my bed around to make it the foot).

Now I needed something decent to connect it to, with the ability to run MythTV and watch video at possibly 1080p resolution. Boron used to live in a HTPC case, but it started getting a little crowded and warm and with the construction of my rack the innards were moved to a 19″ case. That meant that I’ve had a spare high-quality case lying around doing nothing for a while. Now I had the opportunity to bring it back into service.

The Core 2 Duo in my gaming machine has done nothing but impress with its performance and cool running, so I knew what I wanted to base this new machine around. The E7200 2.53GHz was the cheapest Core 2 available on Dabs, so into the basket it went. I wasn’t too bothered about having a high-spec for the rest of the system, and indeed it needs to be farily quiet and cool so for graphics I went with the Asustek Radeon HD3450 256MB and a cheap-but-capable Gigabyte motherboard.

The processor ended up getting swapped for the slightly slower one in aluminium, so I got a small upgrade for gaming at the same time. For the OS I’m currently experimenting with MythBuntu for amd64. I’ve also taken another look at LinuxMCE, which I might give a go some time.

The new machine was named barium, and sits fairly neatly under my bedside table.

There are 4 audio zones in the house, each requiring it’s own amplifier and pair of speakers. I’ve just purchased the last of the amplifiers, which completes the selection of hardware that’s necessary within the cabinet. I took the opportunity to rearrange the order of things in the rack a little to tidy things up.

We recently had our latest electricity bill in, and it was pretty huge. To try to reduce the next bill, reduce the heat output of the cabinet and speed up the network I decided to combine 5 switches into one.

Before now all devices in the house have been connected to one of 3 switches: a 5 port gigabit switch (4 usable ports, 1 for uplink), a 24 port managed 10/100 switch, and a 4 port managed gigabit switch (3 usable ports, 1 for uplink. These switches used a combined 51 watts, and are on continuously, although lately I’ve switched the 4 port gigabit switch off to reduce the noise levels in the cabinet.

I have now replaced these 3 switches with a single 24 port unmanaged gigabit switch. It was a 2nd hand purchase from eBay, and had 2 faulty fans. I’ve replaced one of the fans and left the other disconnected with no problems so far. This switch uses about 17 watts of power.

In addition to consuming 34 watts less, I’ve also freed up 1u of space. With all the amplifiers, computers, networking equipment etc. space is starting to become a premium and the weight of the rack is becoming a concern.