My new Chromebook

Those of you who know me personally will probably have heard me talk about how much I like Chromebooks. I like Chromebooks. Not because ChromeOS is amazing, or I love Google (they’re both OK.). Mostly because they are cheap, reasonable quality computers and absolutely because you can run Linux on them. My latest purchase is an Acer Chromebook 14 and here I’m going to describe how I installed Linux on it.


Here’s the outside – very shiny aluminium, I’ve yet to run it under the laser engraver. I’m still trying to decide what I should put on the lid.

whatsapp-image-2016-12-15-at-21-46-27As you can see it has a really nice, vibrant 1080p screen. This was one of the things which sold me on it. I should add that I bought the 4/32GB version with the HD screen. The 2/16GB version comes with a standard definition LCD so it’s definitely worth the upgrade.


To install Linux, first flip over your new computer and void it’s warranty by opening the back. There are 10 screws to remove and the cover will snap off. Note that not all screws are the same length, so be sure to take note for re-assembly.


With the back removed you’ll be greeted by the insides of the machine. We need to remove the write protect screws which prevent modifications to the BIOS. img_20161215_224310

Here is one of the screws, located next to the Wi-Fi module. I unscrewed it, covered the electrical contacts on the motherboard with some plastic (PVC or masking tape would probably be the best thing if you have some), and put the screw back in. Since this laptop has apparently two write protect screws it’s probably better to replace them for mechanical stability into the future.


And here is the other screw, the same procedure applies. It is located at the top of the motherboard next to the battery. When both screws are masked or removed, you can replace the back of the laptop (it will snap into place as you put the screws in) and boot the machine.

First boot into developer mode  – press and hold the Esc and Refresh keys together, then press the Power button (while still holding the other two keys), then at the recovery screen —the screen with the yellow exclamation point—press Ctrl+D. Everything on the device will be wiped and you’ll have to re-login and re-configure the Wi-Fi. When this is done (it might take 2 reboots), head on over to MrChromebox for the bios modification script. I’ve used scripts from in the past, which have been excellent – however the Acer Chromebook 14 (model CB3-431) is a Braswell based device and MrChromebox seems to have the better BIOS payload at the moment. When the device restarts (after you’ve configured Wi-Fi again) don’t login, but instead press CTRL+ALT + => to get into the CROSH shell. The username is chronos and there’s no default password set.

From here you can download the BIOS update and the script to upload it. I flashed a new SeaBIOS (RW_Legacy) and also changed the boot flags to shorten the developer screen to 1 second. After this I rebooted the machine and inserted a USB key with the latest Gallium OS image onboard. Specifically, I downloaded the nightly build targeted for Braswell (so it’s a bit bleeding edge) and then flashed it using Win32DiskImager as per these awesome instructions. When powering your Chromebook back up, make sure that the USB key is inserted and press ESC at the SeaBIOS screen to open the boot menu, from which you should choose USB. From this point Gallium OS installation was straightforward, completed by following the prompts on screen. Unless you perform some additional steps, this process will completely erase ChromeOS from the device and give you a formatted 32Gb eMMC drive with Linux with any free space left for your use. Unfortunately the eMMC (like the RAM) is non-upgradeable.

It’s worth noting that my first choice OS for this device was Ubuntu, however due to some graphics card driver issues, it doesn’t boot (yet). This is why I’ll be running Gallium OS at least until Ubuntu catches up. So far I’m very happy with the new OS, however it’s worth noting that there are still some open issues with Gallium OS on the Acer Chromebook 14, most significantly the soundcard doesn’t work (and in some cases has been melting). I anticipate these things will get fixed in time, however there’s no guarantee. I plan to acquire some bluetooth headphones which will make the sound issue irrelevant for most use cases.


I’m really grateful to Mr.Chromebox and John Lewis, and a bunch of Linux gurus way smarter than me for doing all this work to get Linux running stably on these nice, cheap laptops. I hope this little not very in depth guide has cast some light on the process of installing Linux on your Chromebook and in particular the new all aluminium Acer Chromebook 14. If you do try to install Linux, it’s entirely at your own risk (and you’ll invalidate your warranty in the process) – however, I would say it’s definitely well worth doing if you succeed. Best of luck!



Dear Brexiteer. What we need you to do now.

Pretty much spot on!


So well done, first of all. You listened to the arguments, the same ones I listened to. You heard all the same information I did, you listened to the same debates that I did, but you voted to leave. And you won. I take that – it was a democratic process and sometimes in the democratic process you lose, as I have done.

The referendum has activated the political energies of people who haven’t been interested in politics for some time, so we are told, and many of them are like you, who voted to leave. So here’s the plea of the losing side to you now.

Firstly, don’t stop – don’t stop with your political passion and activism, because we need you now. We need you to be active, we need you to keep talking to the people who you trusted with this vote, and we need you to…

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The summer of Summer Student – 10 year Reunion!

10 years ago this summer, I arrived for the second time in Geneva for a 12 week internship at CERN. It was without doubt the best summer work placement I did in between leaving school and getting my first ‘proper’ job. Here is a picture of me, 10 years ago taken at about 5am half way up the Jura mountain headed for a sunrise breakfast after partying all night at a “kitchen party”.


The real purpose of this post, beyond reminiscences about a great time in my life and the lives of many others, is to encourage all of you who were part of it to come back to CERN this September for our 10 year reunion. Myself and some of the other former summies who are still lucky enough to be in residence are putting together some activities, which will include a tour of some surface buildings, possibly a guest lecture/screening of memorable photos and video messages from anyone unable to attend, a visit to the Kitchen in Building 38 (where the KP’s began) and probably dinner (possibly somewhere slightly more posh than R1) and drinks afterwards.

The date for your diary is Saturday 19th September, afternoon and evening.

Partners, spouses, boyfriends, girlfriends and children are all welcome. If you want to attend please drop me a line/facebook/email and I’ll send you the exact details!

There is also a facebook event you can join.

jimmy jura and the sunriseFor those who are unfamiliar with the CERN summer student programme – Official Page,  or haven’t had the pleasure of ever being a summer student the basics are (or at least used to be) as follows:

  • Up to 13 weeks paid internship at the CERN site in Geneva
  • Students selected from member states on the basis of an application form to be submitted in December of the preceding year.
  • Each student is selected for a technical project broadly aligned to his or her field of study, and supervised by a researcher or CERN staff member
  • All students are encouraged to attend a 6 week lecture course, covering all aspects of Physics from the very small (High Energy Particles) to the very big (Astrophysics), as well as many more practical details on how to construct and operate CERN scale particle accelerators, including signal acquisition and computing.
  • This experience is shared with approximately 150 other official summer students and countless more less official summer students who have managed to get to CERN for the summer.

Since I finished the programme I’ve done as much as I can to promote it to university students I’ve run into over the years. However the subject of this post is ALL THE FUN I had during my summer, outside of office hours!

Being in the heart of Europe with 150 other highly educated young people from all across Europe and beyond, all in receipt of a reasonable salary (which at the time was little short of a fortune by our meagre student standards), was a recipe for lots of fun. We had fun in many ways, and I have over 1000 photos in a shoebox at home which testify to the majority of our escapades. Here are some particular highlights, described mostly for the benefit for those who weren’t there or who have forgotten:

Fondue on the Roof

One lunchtime I was sitting in the restaurant with my friend Jakub and we decided to organise an exclusive rooftop fondue on top of one of the accessible roofs on the campus. We invited selected friends, and set off for the roof one evening that week with our sleeping bags, a fondue set, some warm clothes a guitar and a harmonica. And some red wine. It got rather cold at night, and I had a horrendous headache the next day. But it was all worth it.

Swimming in the lake at Annecy

Having lived mostly in London for the preceding 12 years of my life, I wasn’t too accustomed to the pleasures of life ‘in the wild’ such as dipping your toes in rivers and swimming in lakes. One sunny Saturday day I hitched a ride with some of my mostly Danish friends to the Aguile du Midi cable car, returning via Annecy. They had located a tree leaning over the lake with a rope swing. I’ll always remember how the cold the water was when I dropped in off the end of the rope and ended up fully submerged in the lake. Nobody told me to breath in before letting go, fortunately I didn’t swallow that much! Later that evening we had pizza on the lakeside and watched the spectacular annual Annecy Fireworks.

The front of the 2005 Summer Student T-shirt

Kitchen Parades

A hand-me-down term from unknown previous summer students, our weekly (Wednesdays, if I recall correctly…) party session, was referred to as a Kitchen Parade. Presumably this is some corruption of a Kitchen Party by a non-native english speaker, quite probably under the influence of intoxicating liquor. Like many informal aspects of the summer student programme, these parties were spontaneously (and excellently) organised by random groups of students, each taking their turn. Typically a party collection was taken in morning lectures by passing an empty cereal carton along the rows of seated students in the main auditorium, with the ‘fee’ for the party scrawled on one of the box flaps in Swiss Francs and an equivalent in Euros. Someone always managed to find a car and head to the supermarket for the prerequisite large quantities of alcohol. Some of the more memorable party themes were:

  • Bad taste party (come in fancy dress, so long as it’s in poor taste)
  • Toga party
  • Cross dressing party (boys dress as girls, girls dress as boys…)
  • Scotish/Irish party (whiskey drinking obligatory)
  • A delicious dinner cooked for us by the Italian students (more dignified than your typical party)
  • Lots of others I can’t remember.

Field trips

We all took advantage of the weekends to visit major cities nearby, from downtown Geneva, across into Italy, France and also more central Switzerland. I personally enjoyed a great trip to Zurich with quite a few awesome people I’m still in touch with, and a weekend in Milan and Turin that included seeing the breathtaking Last Supper by Leonardo Da Vinci. Visits to the Last Supper are typically booked up years in advance by tour groups and organised parties, however a fellow summer student passed on some truly amazing and invaluable advice (I’m not sure if it still works today… if you are successful please let me know!). When we arrived at the church of Santa Maria we sat on the benches and waited for a tour bus to arrive, before pouncing on the tour leader to ask if they had any spare tickets – as for any given coach party there are always going to be a couple of people who cancel or are ill, so can’t use their tickets. On our second attempt we were successful and purchased three tickets for ourselves at face value from the guide!

The names of all the 2005 summer students. It would be great to hear from as many as possible to find out what you're all doing now!

The names of all the 2005 summer students. It would be great to hear from as many as possible to find out what you’re all doing now!


The real purpose of this post, beyond reminiscences about a great time in my life and the lives of many others, is to encourage all of you who were part of it to come back to CERN this September for our 10 year reunion. Myself and some of the other former summies who are still lucky enough to be in residence are putting together some activities, which will include a tour of some surface buildings, possibly a guest lecture/screening of memorable photos and video messages from anyone unable to attend, a visit to the Kitchen in Building 38 (where the KP’s began) and probably dinner (possibly somewhere slightly more posh than R1) and drinks afterwards.

The date for your diary is Saturday 19th September, afternoon and evening.

Partners, spouses, boyfriends, girlfriends and children are all welcome. If you want to attend please drop me a line/facebook/email and I’ll send you the exact details!

Raspberry Pi for Radiation Testing

Today I’ve been working on a radiation qualification test for three different types of bridge diodes.

Top view showing transformer, resistors, terminals and bridge diodes under test.

Top view showing transformer, resistors, terminals and bridge diodes under test.

The test set-up is as follows:

1) Pair of custom PCB’s located within the radiation test area

2) MCA24 cables (24 cores) linking the test area to a safe zone for the measurement electronics, 230V power is also available within the test zone.

3) Two identical custom PCB’s in the safe area, used for pin-out from the MCA24 cables with their Sub-D 25 (Think parallel port!) outputs

4) Two Arduino Mega 2560’s with 15 of their 16 analogue inputs used to measure the output voltages of the bridge diodes at regular intervals throughout the test, outputting blocks of data (100 samples per channel, taken consecutively) over serial at 9600 baud.

5) A Raspberry Pi B+ running command line raspbian, with modifications to auto-login and run a simple shell script at startup.

The Input voltage to the bridge diodes is approx 19V (from a 230/12 volt transformer with no load), and the RMS DC output is 4.8V. The 100Hz ‘lumpy’ DC is read into the Arduino ADC’s via a potential divider network with one 8.2K Ohm resistor on top and a 3.3K Ohm resistor on the bottom – the more observant will note that this will produce clipping at the peaks, however I hope with the lengths of cables (voltage drop and capacitance) between the test and safe zones, that this will not be an issue. In any case the aim of the exercise is just to verify that radiation doesn’t cause any unexpected catastrophic failures in the diodes, so a continuous saturation reading isn’t a particular issue as I’m looking for dramatic changes in behaviour.

Samples are sent over the serial port at 59 second intervals (there’s a microsecond offset too so that it will wrap over the 100Hz waveforms, rather than locking in at a particular offset.

And the bottom of the PCB with the 5 remaining bridge  diodes. These should have been on the top, but I made a mirroring error with the package in the design software.

And the bottom of the PCB with the 5 remaining bridge diodes. These should have been on the top, but I made a mirroring error with the package in the design software.

In setting up the hardware (Arduino and Pi) I wrote this sketch for the Arduino’s and this script for the Pi. Along the way I found this helpful resource on how to login automatically on the Pi and run a script by default on boot. The other thing to add is that the script needs to be set as executable with sudo chmod +x before it will run.

Photos of the setup to follow when I get it mounted.

Britain: For the Love of God, Please Stop David Cameron

A nice little reminder that austerity is negatively correlated with the economic growth required to pay debts.

Benjamin Studebaker

On May 7 (this Thursday), Britain has a general election. I care deeply about British politics–I did my BA over there and will return to do my PhD there this fall. But more importantly, David Cameron’s government has managed the country’s economy with stunning fecklessness, and I couldn’t live with myself if I didn’t do my part to point this out.

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The death of consumer electronics…

What do you buy for the man who has everything? An Omega watch of course… 

Last night I was talking two a couple of my engineer friends at a party (As an Engineer I obviously get invited to, and organise great parties), about the future of consumer electronics. My conclusion was that everyone already owns 90% of everything they’re going to need in terms of consumer electronics:

Landfill Mobiles

  • Smart Phone
  • Tablet
  • Laptop
  • Television/Projector
  • WiFi Router
  • DSLR camera/compact camera/mirror-less camera
  • Action camera
  • In-car GPS
  • Bluetooth Speaker

Beyond these ‘headline’ product categories, there’s no prospect for growth. I already own as many of all of the above items as I require. The consumer electronics industry is no longer about the fulfilment of needs (probably it never was) but more the search for novelty. What will we do when everyone already has 2 tablets, 3 bluetooth speakers and all the electronics retailers have closed?

There are two trends I can see:

1) Niches of niches – Every category is being sub-divided into 10 sub-categories, waterproof smartphone anybody? Mirror-less cameras are basically SLR’s for people with small arms, hands and fingers. Likewise having an MP3 player and a smart phone, and an action camera and a dash-cam. I want a product X in pink…etc.

2)Churn of churn – I’m writing this on a MacBook Pro I bought for a ridiculous sum of money in 2009. It still works perfectly, however I’ve seen plenty of other laptops go to landfill. Today you can easily pick up a reasonable spec plastic laptop for £300, when just 10 years ago you would pay £1000 for something with an equivalent historic market position. Take into account some inflation and today’s cheap laptop costs more like £100 in 2004 money. In summary, the cheaper the thing, the more often you need to replace it.

The main case study in these conclusions is Samsung. Which currently makes 1000’s of different smart phones (Android and Tizen), tablets, telephones, wearables, MP3 players, televisions, robot vacuum cleaners, laptops, computers etc. They have a massive share of the Android market, however these devices are the middle and low end of the smartphone and tablet sector, where margins are significantly less than those commanded by Apple who still hold the high ground. Consequently, Samsung need to shift a lot of product to make even close to the same headline figure as their fruity competitor, who make at least 40% margin (about $250 per phone) on the iPhone 6. Further, they’re heading into all kinds of strange and wonderful product categories (I’m mostly talking about their Gear range), for which consumer demand still seems unproven and recorded sales volumes so far are lamentably low, leaving to significantly reduced profits.

My conclusion for effect 1 is that companies are going to be pouring ever more R&D money (or perhaps consumers, via crowd-funding, as the recent Sony epaper Smart Watch campaign in Japan has shown), for ever smaller product niches. This inevitably means lower volumes. For effect 2, margins have fallen drastically on big ticket items, which is hurting tech companies. The only way to compensate for the lower margins is higher volume, which is achieved in part though the lower price, and in part through a shorter product life-cycle.

I bought a chromebook earlier this year and I love it. I’ve ripped out ChromeOS and it now runs Ubuntu very capably, however it’s never going to last as long as my 5-year-old MacBook. I like it because it’s light, portable and fast, consequently it’s also more likely to get destroyed when I take it out of the house. Where am I going with all of this?

There isn’t enough world for everyone to buy a new set of gadgets every 6 months. We’re going to run out of rare earth metals (that we can reach to mine economically anyway) and choke on toxic waste (if the CO2 doesn’t get to us first). The solution is higher quality, durable products with more in common to those produced in the 1950’s than the 2000’s. I want a laptop that lasts 10 years, a mobile phone that lasts at least 5 and so-on. Once you’ve hit the spot with decent hardware, selling novelty can be all about the software (which is more or less the Apple model these days).

The benefit of all of this? We’ll be a lot richer for it (in terms of natural resources), spend less time in shops buying junk and more time and money buying software which consumes only electricity – that could be generated renewably, or from Nuclear power. You might say that it’s elitist and undemocratic to push for higher quality items and the prices. How the worlds poorest 2Bn people are going to get the benefits of the internet if we raise the cost of a smartphone from $50 to $500 is a problem for another post. 

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Top Tips for Caves Ouvertes, Geneva

This year will be my 4th Caves Ouvertes in the canton of Geneva. Here are some tips to help newbies get the most out of what is arguably the best day of the year to be in Geneva.

The vinyards of Satigny

For the complete beginner, Caves Ouvertes is the annual opening of (almost) all wineries in the Geneva canton of Switzerland. This gives you the chance to try an enormous variety of local wines for free. Most places open between 9-10am and close around 5pm. My top tips for getting the most out of your day are:

  1. Glass (for drinking) – The small size wine glass, normally branded with the logo of Caves Ouvertes for the year will set you back about 5 CHF. I have almost enough of them to use at dinner parties. Provided you can get it home in one piece it’s a great souvenir.
  2. Transportation (for yourself) – Most of the caves (at least in the Satigny/Dardagny region) aren’t far apart. You can get out to the vineyards from Geneva on the local train from Cornavin. When you’ve arrived you can walk between a few of the caves, or alternatively TPG runs a fairly comprehensive shuttle bus service, which might even be free. However since it’s an immensely popular event the shuttle busses often get full to capacity (especially with people heading in to Dardagny at the end of the day), so you might have to wait a very long time. Like many veterans of caves ouvertes, my prefered means of transport is cycling. Obviously you should take care not to cycle dangerously if under the influence of a large quantity of wine.
  3. Transportation (for your purchases) – I normally take a large rucksack with me to accommodate my purchases throughout the day. If you’re a real big spender and happen to live in Switzerland most places will deliver a case or more to your door for free after the event. If you’re only interested in buying the odd bottle you will have to be prepared to carry it around. Also make sure that your chosen luggage has a safe compartment where you can store your glass for those rare moment when you’re not drinking out of it.
  4. Things to bring – In addition to a large rucksack to store your wine, I can recommend bringing a couple of bottles of water (to stave off dehydration, especially if you’re cycling), some sun cream (on the off-chance it isn’t raining), a waterproof (on the off-chance it isn’t sunny) and a fleece for the dual purpose of insulating the bottles against each other and insulating you if it gets cold in the evening. The fleece will also come in handy for drying off your glass in between caves.
  5. What to buy? I’m a big fan of using Caves Ouvertes to stock up on local produce. I’ve had difficulty locating the Cave de Geneve Bacarat Grand Cru in the supermarket (NB this is the top of the range Bacarat, I definitely recommend it), only the regular stuff seems to be on the shelf in the Coop. Chasselas is the entry-level white wine for the region, which can be extremely refreshing when served chilled on a hot summer afternoon. A few caves (such Domaine de la Clé de Sol in Chouilly) specialise in rare varieties of grapes that are no longer mainstream in neighbouring France following the great wine blight of the 19th century. There are also some interesting sweet white wines to be tasted, including the Schreube which is a very distinct sweet white. In the red wine selection most caves offer Gamay as the entry-level bottle, which I find to be slightly watery for my tastes. My recommendation for red wine is the Gamaret, which has a much stronger taste, higher tannin content and goes very well  indeed with beef. Another recommendation if you’re planning to buy wine is to bring cash (Swiss Francs of course), since paying buy card can take a while when the caves are busy. Another note for buying wine is that normally you’ll have to go to the desk to pay, where they will then give you a receipt which you take to the depot (normally next door or across the courtyard) to get your wine.
  6. Where to go? I normally start off from around CERN and head towards Dardagny, via Chouilly, Peissy and Satigny. One day I’d like to go to the other side of the lake, I’ve heard rumours that it’s also very good, especially if you have a bike since the caves are farther apart. Dardagny becomes something of a party town with live music and food stands in the main street. Domaine des trois etoiles in Satigny normally has a good live band as well as great views over the city from the vineyards. Here is a link to an excellent google map with the positions of all the caves in the Geneva region.
  7. What to eat? A hard day of wine tasting calls for some serious nourishment. Most places will provide something for you to eat as you taste, ranging from literally a few crumbs of bread in some places to a gourmet selection of cheese and charcuterie in others. Prices for food also vary from free all the way to expensive. A lot of caves also have food stalls with home-made fayre, or if you’re in one of the larger towns there will probably be plenty of food market stalls to choose from.
  8. And finally, if you’re had a superb day wine tasting don’t forget to drink plenty of water before going to bed!

A gateway to the chateau in Chouilly

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Druk White Lotus School – Video O&M’s

When the solar power system at the Druk White Lotus School in Ladakh was first commissioned in October 2008, a number of key operations (start-up, shut down etc.) were filmed to facilitate future operation of the system. Here is an index of the videos, hopefully it will prove useful to those now in charge of the system.

Videos (Youtube)

How to turn on the system

Data Storage operation

Switching from Grid to Generator supply

Surge Protector periodic inspection

Fault Clearance Procedure


General isolation use procedure

MCB Box contents – description

Cleaning procedure

Starting Generator Procedure

Clear Warning from master inverter

DC Isolation procedure

Password entry

Battery Temperature Sensor Replacement

Generator – Turning off procedure

Arduinopower – One from the archive

An Arduino based desktop power meter
Arduino Power mock-up

This page is all about my attempt to build a desktop scale power meter, based on the arduino platform. It was a project I worked on for some time in 2009, before I decided to buy a house and lost all my free time to mortgage calculations. In the end I produced the first prototype, but the power readings were not as accurate as I’d hoped for, though all of the interfacing between the arduino and the ADE 7753 worked fine. None the less, I’m happy for anyone who is in need of a reference design to pick this up and use it as per the Creative Commons license. All of the information below has been rescued from the site which I originally set up for the project and have now mothballed. I will upload the schematics and libraries to github when I have time, the source code is already on this blog here.

Latest (Updated 28/10/09)!

I’ve completed the first pass of the design, did the CAM scrips in EagleCad and sent it off to those nice people at to make it for me on the 13th October. All the current files in downloads are as my first ‘production’ version. I’m still waiting for the boards to arrive (they’re being posted Royal Mail unfortunately). I’ve also made some changes to the BOM, adding parts I don’t have in my big bag full of parts, so I’ll need to order a few bits & bobs before I can start soldering up the first one. Exciting! Today I also ordered a stack of books on Python, Apache and MySQL to sort out the PC end of the integration.

Progress as of 27/09/09

I’ve had a think about the things that the next version of this board should do. The list is at the bottom of this post.

Completely revised the PCB layout over the weekend with some significant (hopefully!) improvements. The Eaglecad autorouter now does 100% of the routing, with a little persuasion. The main issue I came across during design was the need for very large track widths to accommodate the 13A from a socket outlet, hopefully this is covered by having wide tracks on both sides of the board. I did look at introducing an earth/ground grid (just like on the Arduino board) but decided not to as it didn’t actually do very much due to the large clearances required for the mains tracks. Also worth noting, the transformer seems to be the wrong way round (tracks would be shorter if it was flipped 180 degrees) but this seems to make the autoroute more complicated! All the new stuff is on the download page. Should be ready to get one made any day now.

Also, I stumbled upon a reference design here and here, (maybe it was in the data sheet all along?) though they’re all in chinese so I’m not exactly sure what to make of them till I can get it explained by a chinese speaker.

Progress to date:

27/09/09, hopefully all the things wrong with the version from the 9th September have been looked at and fixed. I’ve done a ‘mock up’ using some cardboard and a scale print out. A picture of the mock up is at the top of the page. There are still a couple of tracks that look a bit too small/rough, but generally everything is at least 12mil wide, which should be plenty. The AC tracks carrying 13A are now double sided and 160mil wide with a decent separation between them.

09/09/09, I’ve done a preliminary circuit design and put the components on an Arduino shield. So far I haven’t got round to verifying the design in any way shape or form. The component list is at the bottom of this post.

To do:

Verify design a bit more

Check the PCB design is ok

Make one!

Test + write arduino code.


The idea is an accurate desktop scale power meter, suitable for measuring individual power usage at (say) a desk. Arduino is a great platform, so it seems like a good thing to base the design on. The idea is to make a plugable device that can be slotted on top of the arduino, called a shield. The principle of this shield will be to work with the Bluetooth Arduino and the USB Arduino duemilanove. The other ‘big idea’ is to include a power supply on board which can drive the arduino in both cases – specifically this is ‘challenging’ because the bluetooth arduino doesn’t accept much above 5V using it’s onboard regulator. The duemilanove accepts a wider range of voltages, so no problem.  Thanks should go to Duncan Wilson for his support in encouraging me to develop it this far (hopefully I can take it far enough to make something workable).

Why this project is a bit different to all the other power meters out there:

I’ve based the design on the Analogue Devices ADE 7753 IC, which is a custom measurement ASIC. This approach has a number of benefits, including having hopefully good accuracy and freeing up arduino processor and memory to do lots of other things more interesting than calculate power measurements. Communication (haven’t quite got that far yet) will be over an SPI type bus or similar.. Power measurement will be via a CT, with a resistive potential divider to measure voltage.

Version 2

(Yes I know version 1 still isn’t even anywhere near finished, but I had a list of things to add to it in my head already and thought I’d note them down here).

  • Additional ports/connector blocks to allow connection of an external CT and burden resistor
  • Revise the way the incoming ports are set-up so that the earth-neutral connections can be avoided or deliberately introduced without the need for jumpers
  • Somehow re-design things to allow XBEE compatibility, this is going to be a bit tough as the relay and other components are quite tall.
  • Add a decent amount of flash memory (8megish) to allow off-network recording
  • Include opto-isolators so that it can be plugged in via USB directly without risk of exploding the computer.
  • Develop/check pin outs for a display (probably using Sparkfun large LED display modules) to indicate energy usage, and also a PIR sensor to measure occupancy.

Circuit Diagram:

Latest 13th October 09

Eagle Cad Format – link to be added

PCB layout:

Latest 13th October 09 – the ones I actually got made

Eagle Cad Format– link to be added

Eagle Cad Library (with the ADE7753 chip in, the mask isn’t quite right!) – link to be added

Thanks to David Sjunnesson for some very good feedback in helping to get things right.

Component list:

 NPN darlington   transistor,TIP102 8A   Each   £0.62 £7.44
 2512 SMT thick film chip resistor,22R   1W   Each (In a Pack of 10) £0.15   £3.00
 ADE7753 1-phase energy metering SSOP   Each £5.00 £30.00
 PCB mount transformer,1VA 2×0-24V o/p   Each £2.39 £26.29
 AS-100 current transformer,15A   20-200kHz   Each £0.49 £2.45
 SMT Crystal,3.579545MHz 86SMX   Each (In a Pack of 5) £0.97   £9.70
 CRG0805 SMT chip resistor,1K 0.125W   Each (In a Pack of 50) £0.03   £3.00
 0805 X7R ceramic capacitor,33nF 50V   Each (In a Pack of 50) £0.033   £3.30
 0805 X7R ceramic capacitor, 25V 0.1uF   Each (In a Pack of 50) £0.022   £1.10
 0805 C0G ceramic capacitor,22pF 50V   Each (In a Pack of 25) £0.03   £1.50
 SRE Aluminium Radial Cap,35V,22uF   Each (In a Pack of 5) £0.12   £1.80
 GA Al electrolytic cap,10uF 16V   Each (In a Pack of 25) £0.11   £2.75
 SPDT PCB power relay,16A 5Vdc coil   Each £2.88 £28.80
 Rectifier diode,BAS316 0.25A 85V   Each (In a Pack of 50) £0.079   £3.95
 Reg Standard Lin Fix Pos 5V 2.2A   3TO-220   Each (In a Pack of 5) £0.42   £4.20
 CRG0805 SMT chip resistor,560K 0.125W   Each (In a Pack of 50) £0.03   £1.50
 CRG0805 SMT chip resistor,680K 0.125W   Each (In a Pack of 50) £0.03   £1.50

Efficient garment storage and retrival management operational systems

Mananaging a highly efficient garment retrival and storage operation isn’t as easy as you might think. The first mistake most people make when considering running such an operation is to think that it is easy. By following this guide you too can learn how to run, manage, operate, integrate and searate all your garment management functions for conference occasions. 


This article uses highly technical and specific terminology relevant to garment retrival and storage operations, please familiarise yourself with the terms below before moving on to the main article.

Garment – A thing somebody wears. Typically in winter this is a coat. When people come inside they usually take off their outer garment and have to put it somewhere. Storage and retrival of such garments is our business.

Cloakroom – Shorthand for a garment storage and retrival service.

Tickets – The lifeblood of your garment storage and retrival service, without a ticket the efficiency of garment retrival is heavily compromised.

Conference – A distraction from the garment retrival and storage service. People turn up to meet each other and listen to yet more people speaking about things which they find interesting. Do not let yourself get distracted from the main business of garment retrival and storage by the conference events. To do so is to invite chaos and disaster.

Garment storage and retrival unit  – another term for the individuals who actually do the garment storage and retrival operations. Like most individuals they can be motivated by smiles, praise for efficient operation, tips and chocolate treats.

Desk – an item of furniture which is used to prevent members of the public from entering the garment retrival and storage area. Should members of the public or conference guests get behind the desk then you will need to ask them to politely return to their designated area.


Like any well run organisation, the secret is a highly motivated team of dynamic individuals working together as one.

When thinking about and organising your garment storage and retrival operation, simply bear in mind these five points to avoid going wrong, making mistakes or disappointing your garment retrievers.

The five tenants of garment retrival, according to me:

Rule 1 – Respect the garments.

Garments are peoples prized possessions, you are being entrusted with them for just a short period of time and it’s important to take care of them. To ensure a successful relationship with your customers it you should avoid the following disrespectful activities:

  • Setting fire to things
  • Performing fashion shows with deposited garments
  • Loud music, especially when the music shows bad taste
  • Rain, wind or extreme weather events
  • Fighting (with anyone)
  • Excessive partying during the opening hours of the conference.

Rule 2 – Organise, everything.

Organisation is the key to success. Numbering everything is the key to organisation, which is the key to success. Tickets are the key to numbering everything, which is the key to organisation, which is the key to success. 

Because chaos leads to confusion leads to lost garments leads to fear leads to the dark side.

Because chaos leads to confusion leads to lost garments leads to fear leads to the dark side.

Rule 3 – No pets or live animals

Working with live animals in a garment storage and retrival service is to invite disaster, wether they be wild animals, strays or domesticated pets. When customers are checking in their garments be sure to inspect them for signs of animals hiding inside pockets or sleeves. Should you discover after the fact that a customer has deposited an animal in addition to their garment, their pet should immediately be moved to the lost and found desk even if it is very cute.

Rule 4 – Form an orderly queue

Persuading members of the public and conference guests to form an orderly and directed queue for the storage or retrival of garments. Equally, if your garment storage and retrival units get out of line be sure to put them in an orderly queue as well. 

For some reason this symbol reminds me of Halflife.

For some reason this symbol reminds me of Halflife.

Rule 5 – There is no rule 5

Because I got bored of this article at Rule 3, and probably so did you. Likewise, if you’re still reading this and haven’t realised it’s a spoof then the joke is on you 😉

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