Powering non-PoE devices from a PoE switch

A brief note explaining how to use a standard Power Over Ethernet (PoE) switch to power non-PoE equipment.

Introduction
These days Power over Ethernet (PoE) switches are standard in larger organisations as they are typically used to connect desk phones on users desks using one cat-5 or cat-6 data cable.  This one cable provides both the data and power connections that the phone needs and saves time, effort and power (and therefore costs) in the modern office.

Increasingly you will find PoE is being used in homes and smaller business to power WiFi access points or small security / CCTV cameras where the savings are even more noticeable.  For example, if you decide to install a security camera outside your house you can easily see that only having to run one cable to the camera greatly simplifies the installation and saves on installation costs as no separate power socket or adapter is needed.

The only drawback to this approach is that you have to already have a PoE switch and you would normally need to buy a PoE-compatible camera. At least - you did need to buy a PoE-compatible camera.  This note explains how you can use a normal 12V / Ethernet camera and a nice piece of technology from TP-Link - the TP-LINK TL-POE10R PoE Splitter.

What is Power over Ethernet?
Power over Ethernet or PoE is a general term that is used to describe systems that pass power alongside data on twisted-pair (Cat-5 or Cat-6) Ethernet cables.  There are several common techniques used to transmit this power but in this note I'll stick to the IEEE 802.3 standard which defines the power supplied to be typically 15.4W or 25.5W for PoE+.

Anyone wanting to learn more about other alternative PoE systems are encouraged to look at the PoE entry on Wikipedia.


What is a PoE Switch?
A PoE Switch is just like any other Ethernet switch - except it is designed to provide 15.4W of power, on demand, down the Ethernet cable to the end device along with the Ethernet data signals.  Similarly, a PoE+ switch can provide upto 25.5W.  In my network I use a 24-port PoE+ Gigabit Ethernet switch similar to this TP-Link T1600G-28PS JetStream 24-Port Gigabit Smart PoE+ Switch.  You should consider one of these - or maybe a smaller 4 or 8 Port Gigabit PoE Switch to power your IP cameras if you are looking to do the same in your home or small business.

What is a PoE Splitter?
A PoE Splitter is a small device that passes the Ethernet data signals from input to output and at the same time draws power from the incoming PoE signal and provides a stable output power feed suitable for small devices such as a camera or WiFi access point as this diagram from TP-Link's user guide shows:

You can see from the diagram that this little device supplies power AND data to the end device but only has one cable connecting it to the switch.  To illustrate this the image below shows that I have powered a small 5-port Cisco switch from the unit.  The purple wire on the left connects to my PoE switch; the grey wire passes the Ethernet signal from the splitter to the Cisco switch and the black wire supplies power from the splitter to the switch.

In my next project I will be using this splitter to power a Raspberry Pi together with a Camera Module and LED light source as I construct a wildlife camera to watch the wildlife using the small pond in my garden.

I hope this note has been of use to you. I'll refer to it when I write up the Raspberry Pi outdoor wildlife camera project.

How to mount Google Drive on Linux

A short tutorial showing you how to install google-drive-ocamlfuse on a Linux Mint 17 system to access the contents of your Google Drive

Introduction
Most linux users who have tried to access their Google Drive contents will realise that there isn't an official Drive client for Linux yet - despite the wide availability of Drive clients for Windows and for Android devices.  Luckily there are alternatives available and this article shows you how to install google-drive-ocamlfuse on a system running Mint-17.

What is google-drive-ocamlfuse?
Technically, google-drive-ocamlfuse is a FUSE filesystem backed by Google Drive, written in OCaml. It lets you mount your Google Drive on Linux in a folder you choose during setup.  It has the following features:

• Full read/write access to ordinary files and folders
• Read-only access to Google Docs, Sheets, and Slides (exported to configurable formats)
• Multiple account support
• Duplicate file handling
• Access to trash (.Trash directory)

The version I installed at the time I wrote this was google-drive-ocamlfuse 0.5.16.  The software is hosted on GitHub and more information is available on the project's GitHub page.

Installation instructions
The author has set up a .deb repository for installation under Ubuntu 14.04, 12.04 etc.  This means that any ubuntu derivatives (such as Mint) can use the same repository to install google-drive-ocamlfuse. To do this, open a Terminal window and enter the commands below

$ sudo add-apt-repository ppa:alessandro-strada/ppa
$ sudo apt-get update
$ sudo apt-get install google-drive-ocamlfuse

Once this has completed you need to configure google-drive-ocamlfuse to suit your system. First run google-drive-ocamlfuse without any parameters

$ google-drive-ocamlfuse

This command will create a folder (~/.gdfuse/default) containing the configuration files for the application and will also open a web browser asking you to confirm that you want the application to access your Google Drive.

Once access has been authorised the web browser will close and you will be returned to your Terminal window. You can then mount your Google Drive folder in your filesystem. In this tutorial I decided to keep things simple, so I created a Drive folder in my home area and configured google-drive-ocamlfuse to mount my Google Drive at this point.

$ mkdir -p ~/Drive
$ google-drive-ocamlfuse ~/Drive

When you've done this you should see the files appearing as part of your new ~/Drive folder, depending on the speed of your Internet connection. Now be aware that there are two things you need to understand in order to get the best from this tutorial:

• The first is that your Google Drive is mapped from the web. The files in your Google Drive stay in the cloud and are not synchronised with your local hard drive. This means that files take a while to open and close, as they are literally coming in from Google's servers. It also means that no Internet access equals no access to your Google Drive files. You can get round this by using rsync to sync or mirror another local folder with your Drive folder but that is a tutorial for another day.
• The second is that the mount of your Google Drive is lost after a reboot or if you log out of your session. To get around this I added a couple of steps to the installation instructions you normally find so that your Google Drive reappears at the start of a new session.

Automounting your Google Drive
Open a Terminal session and create a shell script named gdfuse in /usr/bin.

$ sudo nano /usr/bin/gdfuse

Copy and paste the following lines into the script changing $username to match your username:

#!/bin/bash

su $username -l -c "google-drive-ocamlfuse -label $1 $*"
exit 0

Give the new script exec permissions

$ sudo chmod +x /usr/bin/gdfuse

Now edit /etc/fstab

$ sudo nano /etc/fstab

And add the following lines like this: (but remember to change uid and gid and /path/to/your/gdrive in the line below to the values of your username and of the path to your Google Drive folder accordingly.)

# Google Drive Automount
gdfuse#default /path/to/your/gdrive fuse uid=1000,gid=1000 0 0

You can then use mount to mount your Google Drive (again, with your Google Drive path in place of my example):

$ sudo mount /path/to/your/gdrive

That should be it. To test this, reboot the workstation and log back in again. After your desktop is ready you should see the Drive folder once more in place and if you click on the folder your Google Drive files should be visible again.

One final touch I did was to alter the file icon for my Drive folder so that it looked like a Google Drive folder.  I downloaded a suitable Drive icon from the web and adjusted the Properties of my Drive folder so that it showed the Google Drive icon instead.

I hope this tutorial has been of use to you. The steps involved took about ten minutes to complete and finally I have access to my Google Drive contents from my Mint workstation.

Adding new users on Mint 13 XFCE?

I've been advocating using Linux Mint 13 XFCE (codename MAYA) as a replacement operating system for older computers that were running Windows XP.  It's simple to use, fast, capable of most basic uses and, importantly, it's free!

I have also used Mint 13 on a number of occasions for single-task systems that just require a single user to do a single job.  But today I went to add a second user on a small system I am testing and I found that the basic installation of Mint 13 XFCE does not include the graphical tools to add new users.  You'd expect to find these by clicking  on Menu then selecting System and then Users and Groups.

Here is a simple one-line command to add this tool back in:

Open Terminal and enter the following line:

$ sudo apt-get install gnome-system-tools

Once the command has finished executing you can find the graphical tools to add users under System --> Users and Groups
Enjoy!

How to install an SSD in a Dell D430 laptop

Speed up your laptop with a solid-state drive
You may know from elsewhere on my blog that I have a tiny Dell D430 laptop that I use for portability when I'm out and about and want more power than just a tablet alone.

I'd been looking at ways to speed the laptop up and started to look specifically at replacing the 1.8" 4,200rpm 60G Toshiba hard disk with something a bit faster.  The Toshiba drive is tiny and very low powered, but it is sloooow.  Indeed, it is so slow that it ranks 3189 out of 3192 - literally fourth from the bottom - of Passmark's November 2014 Hard Disk benchmark!

No prizes for guessing I need to replace this to get some performance out of this laptop. The obvious direction is to install an SSD - or a Solid State Disk. The question is - How?  The Dell D430 hard disk sits under the battery and is shown outlined in red in this photograph.  You can see that there's no room for a physically larger hard disk.

Add to this the fact that the hard disk interface on the Dell D430 is a PATA or IDE interface and that would normally rule out any SATA devices too.

The only options we have therefore is to replace the disk with a purpose-made SSD that is designed to fit a 1.8" format or to seek an alternative format.  There are a few 1.8" SSDs available (there are a few shown here) so an easy approach would be to buy and install one of these. However, I was looking for something that would likely outlast the Dell, so I looked at using an mSATA SSD and running it using an mSATA to ZIF Adapter.  Not only is the mSATA SSD cheaper to buy, it's transferable and usable in other computers and laptops should the Dell die in the future.

Here's how I did it.  To start, I wanted a clean build of a new OS, so I took a backup of my data from the old hard disk before I started this procedure.  The old disk had Mint 13 on it but I wanted to move to Mint 17 with the new disk and this is best done with a clean install on the new disk.  I'm therefore going to assume that you won't need my help to manage your data or your OS - just the procedure for swapping the old disk for an SSD.

You'll therefore need:

Tools:
a small cross-head screwdriver
possibly a wooden toothpick and a wooden coffee stirrer.

Parts:
An mSATA Solid State Disk (I chose a 120G Crucial m4 mSATA SSD like this)

An mSATA to ZIF adapter card

 

Method:
Start with the laptop powered down and the battery removed

Step 1 - Undo the two screws on the disk caddy

Step 2 - Lift and slide the caddy so it is freed from the plastic clips on the base of the laptop

Step 3 - Gently lift away the disk caddy and put it somewhere safe - with the two screws.

Step 4 - Locate the pull tape on the disk plug. Gently grip and pull this straight up to disconnect it

Step 5 - Lift the old hard drive clear

Step 6 - Ease the rubber case away from the old hard disk. Don't stretch it and don't use anything metal to loosen it.  If necessary use a wooden stirrer to ease the rubber free of the drive.

Step 7 - When the rubber case is loose, gently pick open the ZIF connector lock (it should just flick up, but don't force it)

Step 8 - Here the lock is free and the ZIF connector is ready to have the cable removed.  Slide the rubber case over the connector so you can remove the drive.

Step 9 - Gently pull the connector from the drive.  Use a toothpick to ease it out if it is sticky. Put the drive somewhere safe.

Step 10 - Start to assemble the SSD and the adapter.  Undo the two screws on the adapter

Step 11 - The SSD and adapter are ready - now to connect it up.

Step 12 - Pick open the ZIF connector on the SSD adapter and offer it to the cable.  Make sure the cable goes into the connector and not under it.  Note that here I have inadvertently put the cable in the wrong way round.  More on this later.

Step 13 - Here is the SSD with the cable connected the right way round.  The cable should sit so that it curls or wraps over the top of the SSD.

Step 14 - curl the cable loosely over the top of the SSD and place the SSD top-down in the rubber case.  It will be a loose fit.  Don't worry, it will be fine.

Step 15 - Offer the SSD in the case to the Dell laptop and connect the blue plug to the disk connector on the laptop, pressing it gently so that it clips into place.

Step 16 - Re-attach the disk caddy to hold the SSD in place.  Don't forget to do up the two screws.

Step 17 - Re-connect the battery

That's it, done.  Now turn the laptop over and turn it on.  If you enter the BIOS while the laptop is booting, the new SSD should show itself by advertising its capacity on the Device Info screen as shown here.  If you've managed to get the cable the wrong way round (see Step 12 above) you'll know because there would be no disk found by the BIOS!

For me, I next inserted a prepared USB stick with the install ISO of Mint 17 Cinnamon on it and set about installing a clean, fresh copy of Mint 17.  When this was complete, I then tweaked it from the guide here and tuned it for an SSD using this guide.


Addendum:
Two months after I completed this upgrade I experienced a little problem.  my laptop died.  Well, more exactly, I'd let the laptop go to sleep as I was busy elsewhere.  When I resumed the laptop the system didn't come back to life.  After a power off/power on the system still did not boot.  A view in the BIOS showed no hard disk found.

The SSD had died on me.

Slightly worried by this (my British stiff upper lip here...) I began to search Crucial's web site for a Returns page for SSDs when I chanced upon this article:

Why did my SSD "disappear" from my system?

It turned out that my SSD had suffered from a bug in its firmware and had apparently 'died' as a result of this bug. After following the steps in that article I once again had an operational SSD.  In that article you are also advised to update the firmware of the SSD and this I completed from following the instructions in the SSD Support page

I once again have a fully working Dell D430 with a 120G SSD on board.


Well?  How fast is it?
Let's be clear. You won't get the full speed from your new SSD with the old 100MB/s IDE disk interface on the Dell!  That said; the performance of the Dell is greatly improved by the addition of the disk.  For me, the laptop now boots from power-on to the log-on prompt in a little over twenty five seconds (the BIOS alone takes 8 seconds of this).  And then, from entering my password, it takes a further twenty or so seconds until the desktop is operational. Not bad!

As you'll see from the comments below I was asked what the measured speed differences were.  I must admit, when I first installed the SSD I didn't measure the performance, but I've since popped the old disk back in and run before-and-after speed tests.

The two tests I carried out are simple but indicative. The first uses the Linux dd command as described in Systembash's post to measure write speeds:

$ dd bs=1M count=512 if=/dev/zero of=test conv=fdatasync

When this is run it produces an output like this (this was run on the old Toshiba hard disk)

512+0 records in
512+0 records out
536870912 bytes (537 MB) copied, 36.4651 s, 14.7 MB/s

and the second test uses the hdparm command from Unixcraft's post

$ sudo hdparm -tT /dev/sda

This produces an output like this (again, for the old disk)

/dev/sda:
 Timing cached reads:   1090 MB in  2.00 seconds = 545.34 MB/sec
 Timing buffered disk reads:  32 MB in  3.07 seconds =  10.43 MB/sec

If you run the dd test above, don't forget to delete the test file when you've finished testing - it's 512MB in size!

$ rm test

The results for the Toshiba 60G hard disk and for the Crucial SSD on my laptop are shown in the table below:

Computer	Boot time	dd write speed	Cached Read speed	Buffered Read speed
D430 with Toshiba disk	90s	14.7 MB/s	545.34 MB/s	10.43 MB/s
D430 with Crucial SSD	41s	27.4 MB/s	775.91 MB/s	77.20 MB/s

You can see that the SSD is distinctly faster that the older Toshiba disk, but not by as much as you would expect.  This is due to the restrictions in the D430 design.  Dell built the D430 laptop around Intel's low-power 945GMS chipset and, while the chipset supports both SATA and IDE interfaces, Dell decided to use the much slower IDE interface rather than the SATA interface in the D430 design.  It is this IDE interface that is holding back the performance of the SSD in this laptop.

Conclusion
If you have an old Dell D420 or D430, why not try this upgrade on it rather than just throwing it out.  My costs for this were around £75 (about $120 or €95) (you can click on any of  the orange text in this blog post as they each link to suitable products and articles that back up the points I make).  You can even buy a Dell D430 to do this yourself - a good D430 can cost as little as £50/$80 on ebay.

Running Mint, it is still plenty fast enough for Internet browsing, simple office work and light picture editing.  I'm even coding on it, running IntelliJ while I learn Java.  The device does get a bit warm (I'll get round to improving the cooling later on (using the same approach as I did in this Blog post)) but the battery lasts two and a half hours and it's so light.  the casing is magnesium, so it's very strong and the keyboard is plenty big enough even for my fat fingers.

Fixing the Blinking LED on Intel WiFi cards

Introduction
I've recently got hold of a Dell D430 laptop and installed Mint 13 Maya on it intending to use it as a small laptop to carry around with my photography kit as it's small, light and lasts two hours on a battery charge. Installing Mint wasn't a problem, and I've been surprised how quick the laptop is to use. All the components work as they should and the laptop is fast becoming the first device I reach for when I want something done quickly in the field.

However, like many people, I've had one gripe with whole set up - the annoying flashing WiFi LED just below the screen. This happens because Dell, like many other manufacturers, uses an Intel WiFi chipset in their laptops and the Intel developers who put together the Linux drivers for the chipset decided in their wisdom to make the LED 'flash' to indicate that it was passing traffic. This has annoyed so many people that a quick search will reveal a large number of solutions on the Internet where people in one way or another have 'fixed' this problem in their own particular environments.

So why do I feel the need to write another?

Well, after trying a fair few of these solutions none of them actually worked on my setup. This is not to say that these other solutions do not work - just that I wasn't successful getting them to work for me. So I've written a blog explaining how I turned off the LED rather than just a prescriptive 'do-this-then-that'.

Step One - understanding how to tackle the problem
The Intel WiFi drivers are usually installed as a family of modules that work together with the linux kernel to set up and run the WiFi chipset. Judging by the people with the same hardware as me, at least one of the module names contained the letters 'iwl', so, armed with this, I listed the modules by typing this comment into a Terminal window:

$ lsmod | grep iwl

This gave me the response

$ lsmod | grep iwl
iwl3945                73111  0 
iwl_legacy             71134  1 iwl3945
mac80211              436455  3 iwl3945,iwl_legacy
cfg80211              178679  4 iwl3945,iwl_legacy,mac80211$

So I now need to find out which of these files contain the control for the LED. This leads me to:

Step Two - installing some Linux diagnostic tools
We will need to look at the capabilities of each of these modules to see which one(s) can control the LED and to do this we need to download sysfsutils. This is a set of utilities built upon sysfs, a virtual filing system in more recent kernels that lets you investigate a systems' device tree. To install the tools open a terminal window and in the window type:

$ sudo apt-get update
$ sudo apt-get install sysfsutils

Once the install is complete, you can run the systool command on each of the modules to see which module has a parameter option to control the LED. (in the examples below I chop the end of the report off to save space and make the response more meaningful):

$ systool -m iwl3945 -av
Module = "iwl3945"

  Attributes:
    initstate           = "live"
    refcnt              = "0"
    srcversion          = "301B04B4010DED41B0830D0"
    uevent              = 
    version             = "in-tree:s"

  Parameters:
    antenna             = "0"
    disable_hw_scan     = "0"
    fw_restart          = "1"
    swcrypto            = "1"

  Sections:
    .altinstr_replacement= "0x00000000"
    .altinstructions    = "0x00000000"

    [ -- some output removed for clarity -- ]

$ systool -m iwl_legacy -av
Module = "iwl_legacy"

  Attributes:
    initstate           = "live"
    refcnt              = "1"
    srcversion          = "275221577F5CCA15EDB6755"
    uevent              = 
    version             = "in-tree:"

  Parameters:
    bt_coex_active      = "Y"
    led_mode            = "0"

  Sections:
    .altinstr_replacement= "0x00000000"
    .altinstructions    = "0x00000000"

    [ -- some output removed for clarity -- ]

$

You can see from this that the module iwl3945 does not have a parameter option to set the LED mode but iwl_legacy does have such a parameter - the line led_mode = "0" in the list above. So, to stop the LED flashing we need to configure iwl_legacy to switch the LED on for WiFi active and off for WiFi inactive. But what setting for led_mode should we use? The answer lies in the output of another command:

$ modinfo iwl_legacy
filename:       /lib/modules/3.2.0-23-generic/kernel/drivers/net/wireless/iwlegacy/iwl-legacy.ko
license:        GPL
author:         Copyright(c) 2003-2011 Intel Corporation 
version:        in-tree:
description:    iwl-legacy: common functions for 3945 and 4965
srcversion:     275221577F5CCA15EDB6755
depends:        mac80211,cfg80211
intree:         Y
vermagic:       3.2.0-23-generic SMP mod_unload modversions 686 
parm:           led_mode:0=system default, 1=On(RF On)/Off(RF Off), 2=blinking (int)
parm:           bt_coex_active:enable wifi/bluetooth co-exist (bool)
$

What we want is option 1 - On(RF On)/Off(RF Off). Now we need to configure the module to control the LED this way.

Step Three - making the change.
To make the change to the LED we need to unload the iwl_legacy module, change its configuration file and finally reload the module. In sequence then:

$ sudo modprobe -r iwl_legacy 
FATAL: Module iwl_legacy is in use.
$ 

If you see this, then you've made a mistake. You will need to unload the other iwl module first, as this module is preventing the other from being unloaded. (you will naturally turn off your WiFi connection at the same time, so be careful!) :

$ sudo modprobe -r iwl3945
$ sudo modprobe -r iwl_legacy 
$ 

Now the modules are unloaded you can make the changes.

$ cd /etc/modprobe.d
$ sudo nano iwl_legacy.conf

In nano enter this line then save the file and exit nano.

options iwl_legacy led_mode=1

Now re-start the two modules

$ sudo modprobe iwl_legacy 
$ sudo modprobe iwl3945
$ cd ~
$

Finally check that iwl_legacy is properly configured - and check on your laptop that the LED is behaving as it should.

$ systool -m iwl_legacy -av
Module = "iwl_legacy"

  Attributes:
    initstate           = "live"
    refcnt              = "1"
    srcversion          = "275221577F5CCA15EDB6755"
    uevent              = 
    version             = "in-tree:"

  Parameters:
    bt_coex_active      = "Y"
    led_mode            = "1"

  Sections:
    .altinstr_replacement= "0x00000000"
    .altinstructions    = "0x00000000"

    [ -- some output removed for clarity -- ]

$

Assuming all of the above has been completed and you have a non-blinking LED, the last thing to do is to shut the laptop down completely and then restart it - just to make sure the configuration works the next time it is used.

Conclusion
You should now have a laptop without a blinking LED.  You may also find this approach to tackling the blinking LED problem may be useful with other WiFi chipsets and it would be good to know if this approach helps you stop that annoyingly blinking LED too.  Please add a comment below and let me know.

Update following Mint 17 (Qiana)
I've just updated my D430 to Mint 17 (Cinnamon) and had to repeat the steps in this blog article to stop the blinking LED again!!  You'll be pleased to know that I used the same approach as I presented in this blog and everything was the same except one of the files has changed its name in the new release.

iwl_legacy is now called iwlegacy. This means that this blog article is still valid for Mint 17 - except wherever you read iwl_legacy you should substitute iwlegacy instead.  This also applies to the line you need to put into iwlegacy.conf:

options iwlegacy led_mode=1

Good luck!

Charging your Smartphone while on the move.

Hands up anyone who has had their Smartphone run out of battery just when you needed to make or take that call? Or you turned up at a meeting and you needed to call your boss. Or, more importantly, perhaps your tablet died during the climax of that film or in the final stages of your game.

Or perhaps you're going camping or hiking at the weekend and you want to be sure you can charge your phone while you're away.

I have found a simple solution to all of the above: a charger you can carry with you and use on the go. In fact, all it is is a Rechargeable Battery Pack that you carry with you.

 

When you get the low battery warning from your phone or tablet simply plug in the battery pack, charge your phone and continue using it. It's so simple.  The battery pack I use comes with a built in short microUSB cable so it plugs directly into my work Blackberry or my own personal Sony Xperia Z2.

If I had an Apple iPhone or iPad I could plug in an Apple cable and charge my Apple device just as easily from the USB port.  I'd like to point you at an Apple micro USB to Lightning adapter, but, as usual, Apple won't let me do that.  You'll have to search for these yourselves - or you could get a non-Apple phone and avoid these restrictions altogether.

The Rechargeable Battery Pack will charge my Blackberry around three times and my Xperia one and a half times. You should get two full charges out of the pack on most phones - including the iPhone.  That should be enough for a couple of days use without needing a charger. The charger has four blue LEDs on the top that tell you how much charge is in the unit.  Four LEDs lit means the pack is fully charged; two LEDs lit shows the pack is about half-charged.  The pack is as quick to charge your phone as a high-power normal mains charger.

And an added bonus for me - this battery pack even runs my Raspberry Pi!

Technical Specifications:

• Capacity: 5000mAh, Lithium-polymer battery capable of charging two smartphones at the same time.
• Charges iPhone 2 to 2.5 times, Charges Galaxy S4 about 1.3 times.
• Max output: 5V / 2.5A.
• Suitable for Android and Windows Smartphones, iPhones, iPads and Tablets (you will need to buy an Apple adapter as none are included)
• On a high-power charger the pack is fully recharged in 3.5 hours.
• On a normal charger the pack is recharged in about 6 hours
• Size: 5.1" x 2.75" x 0.31".  One of the thinnest battery packs available.  It's designed to stack behind your phone and you can still use the phone with the charger held behind it

Conclusion

There's simply no excuse.  For the little amount this unit costs - and the convenient size - you really should carry one with you at all times.  It will save you - or your friends - time and time again.

Upgrading to LED lamps really pays for itself!

I've been replacing my older tungsten bulbs for years now, starting with compact fluorescent lamps (CFLs) and more recently directly with LED lamps

Although I'm already saving money having switched to CFLs I'm getting fed up with the low light output, the long start times and the noticeable way the light output decays with time so that all too quickly the lamps become next to useless.  An example are the candle lamps I have in my dining room.

The light fitting held eight 40W tungsten lamps so the room was nice and bright, but at a total of 320W was very expensive to run (over £110 per year using the lamps an average of six hours a day).

I replaced the tungsten lamps with eight 7W compact fluorescents and for a while these have been OK but lately the light output has faded and the electronic ballasts used in the bulbs have started to whine, so these replacements have not only become annoyingly dim but also annoyingly noisy!

They have got to go.

I've been looking for a suitable replacement for these for a while - and while it is easy to justify buying LED bulbs to replace tungsten or halogen lamps you do have to be careful replacing the compact fluorescent lamps because the power savings are nowhere near as great.  However, I think I've found a bargain.  I've found a source of a triple pack of Duracell 4w LED Candle Light Bulbs at a very good price.

Not only are these slightly cooler colour temperature than the old compact fluorescent bulbs, but they are cheaper to replace and run at an even lower wattage so I will make savings when these are fitted.  To prove this I knocked up a quick spreadsheet calculator that you can download here

In the spreadsheet I have assumed that a unit of electricity costs about £0.15 and that the lamps are run for an average of six hours per day.  From this:

• A 40W tungsten lamp costs £13.10 per year in electricity and may need to be replaced twice.
• The 7W CFL costs £2.29 per year to run and may last five years.
• The Duracell 4W LED lamp costs a miserly £1.31 per year to run and should last 10 years. 

When you factor in the lives of the other bulbs and their replacement costs the Duracell LED lamp will pay for itself as a replacement for the compact fluorescents in under two years - and as a replacement for the 40W tungsten bulb in about three months!

You can use the calculator to work out how much you can save, but do bear in mind that if a lamp is only used an hour or so a day (perhaps in a cupboard under the stairs) it may not be worth replacing it at all with an LED lamp.  Just enter the details of the lamps you want to compare in the yellow boxes and adjust the electricity costs and hours per day to suit you and the rest of the sheet re-calculates for you (it should be easy to convert to other currencies too but I'll leave that up to you).

Addendum:
The new LED lamps arrived today and they're all fitted. They're bright with a good colour balance and are noticeably brighter than the old 7W compact fluorescents so that's a good start.  They're instant-on, which means I get light immediately I turn the switch on (not 30 seconds to two minutes afterwards) and they're silent.  No more whistling and whining from the lamps!

Technical Data:

Energy Rating	A+
Power consumption	4W
Lumens	250
Lumens/Watt	63
Colour Temperature	2700K (Warm White)
Expected life	25,000 hours
Power Cycles	approx. 40,000