Beatrix Released (Escape Pod)

Occasionally there is a short story that stands out to me head and shoulders above the crowd. Beatrix Released, by Shaenon K. Garrity, published on Escape Pod this week was one such story. This is a science fiction story, an origin story and a new unique perspective on Miss Potter, a dark secret, her challenges with strict parents and patriarchal authority. It is an ingenious take on maybe how we came to have all those delightfully anthropomorphic tales of small creatures. 

Escape Pod has consistently high production values and in this case they have unerringly matched the very best narrator to the story. Katherine Inskip is entirely believable as Miss Potter. Perhaps it’s her back ground as a scientist and a writer of stories that brings extra authenticity to the narration.

If you only listen to one piece of audio fiction this week, make it Beatrix Released.

Do one thing and do it very well

A design principal that has been proven to be successful is to design a thing to do just one thing and do it well. There are many examples of where this idea has been applied and seen to succeed. The original Ford production line had stations where each was dedicated to one task and designed to to that well. The GNU tools that are most often supplied as part of Linux are designed with the same principal. Each GNU tool is a small program that has one task and is designed to be excellent at performing that task. Like the stations in the Ford production line the GNU tools can be piped together to achieve complex tasks with each element doing their part really well.

So much to do so little to say, but fairy lights

Today has been one of those days where there has been so much to do, so much happening in the news and I’ve been so busy there’s been no space to think of a post for the blog. I’ve been driving for three and a half hours to get to the client’s site and back. I’ve not listened to any podcasts since the news has been to engaging, so nothing to report there as I’ve nothing positive or original to say about Brexit other than I hate portmanteau words and this one is up there with Brangelina; I guess thats not really positive.

fairy lights

The highlight of my day has been the Amazon delivery of LED string fairy lights. 10 meters long battery powered multicoloured fairy lights with a remote control. So at the weekend I can put fairy lights on the outside Christmas tree without having to trail mains cables out the bedroom windows.

I’m up early tomorrow to hit the road again so its an early night and no time to research a proper blog post. This will have to do

Weirdest TV fault

The BBC News at Ten

Our 10 year old 42 inch LG television has a really weird fault. It only ever occurs at the start of the BBC News at 10. During the theme music the screen will go blank and then the sound cuts out. It then appears dead for between 15 and 30 seconds. This will happen one or twice each time the program starts. This is the only program that it happens for. ITV news is fine, other programs at 10pm never cause this fault to trigger. The TV is not using anything fancy just a standard TV antenna. 

The set has done this for a couple of years now, it doesn’t get any better or worse, it doesn’t matter what the weather is. I can’t find any reason for this bizarre fault to occur. One of those strange unaccountable mysteries of life.

Open Bionics

Bionic 3D-printed arm ‘gives confidence’ to young amputees

I saw this story from the BBC today. Back in January 2015 I did an interview with Joel Gibbard about the Open Hand project for the Hacker Public Radio podcast. His Open Hand project has since evolved into Open Bionics which is now delivering his goal of providing affordable prosthetic hands, £5,000 rather than £50,000. Before Open Bionics, because of the cost of prosthetic hands, it has not been affordable to provide hands for children who need a series of different sized custom prosthetics as they grow. 

In the interview Joel spoke about the goals for Open Hand and Open Bionics, it is great to see this amazing project starting to deliver low cost prosthetics to amputees. The Open Bionics Hero Hand has come a long way from the early prototypes.

The interview is still available on the Hacker Public Radio archive, and can be listened to at:

T5 Camper Van Electrics

Space is at a premium when turning a modest sized van such as a Volkswagon T5 into a camper van. The obvious solutions are not necessarily the best or most aesthetically pleasing.

For the low voltage services such as the refrigerator, cabin lights and water pump it’s not sensible to rely upon the automotive 12 Volt battery, it will deplete the charge too much. So an additional leisure battery is required to supplement the power available. The additional leisure battery and the ancillary circuits it feeds need to be kept separate from the original power circuits, this is achieved by using an electronic split-charge-relay. The split-charge-relay only connects the automotive power to the leisure battery when the alternator is producing more than 13.6V. This allows the leisure battery to charge whilst the vehicle is running, but prevents the use of the automotive battery power at other times. It also prevents the heavy current demands of the starter motor from impacting the leisure battery, which is not designed for that kind of service.

There are a number of options for locating the leisure battery. My choice was to house it under the driver’s seat, rather than taking up space in the rear cabinets (space is at a premium there). For this you have to select a suitably size battery. I chose a Powerline Leisure XV190 battery which is low enough to fit. The battery is secured to a bracket in the base of the seat-box using a pair of heavy duty luggage straps to ensure that it is held firmly.

In addition to having low voltage circuits, it is also useful to add a mains power hookup to have 13A sockets available in the rear cabin. For this we need circuit protection, an RCD to protect the users and over-current protection for the cabling. It is important to use suitable impact resistant fire retardant mains cabling to connect up to the sockets, ordinary PVC flex or even twin and earth cabling is not really suitable. The mains feed also gives the option of installing a mains powered battery charger for when on site for more than a couple of days (that’s something I’ll add later).

From my research there appear to be a number of options as to where the mains hook-up connection can be fitted on a T5. Each has their own pro’s and cons:

  • A power hookup connector cut into the side of the van – looks ugly
  • A 16A connector on the underside of the rear behind the rear bumper – likely to get very dirty and corroded
  • Concealed behind the rear quarter panel – only suitable for tailgate models, quite a lot of fiddly work to add the hinges to the panel and might damage paintwork
  • Under the bonnet in the battery compartment – confined space – have to open bonnet to plug in

I went for the last option and worked carefully around the space issue. 

Most camper conversions I’ve seen, approach electrical circuit protection by installing a small consumer unit. There are three downsides to that approach:

  • They are not small, its an ugly metal box with a DIN rail, bus bar, RCD module and circuit breaker. You have to find the space to fit one (and space is at a premium) , it also has to be accessible so that you can reset the RCD or circuit breaker.
  • When you’ve found a space to fit it, that may not be close enough to the power inlet connector (it should be as close as possible since its there to protect the power cables in van), so its difficult to find a suitable place.
  • They are expensive overkill for the job in hand. You are only needing to protect a single circuit and are unlikely to consume more than 13A, at best the hookup is going to supply 16A.

I chose to use a metal clad RCD 13A spur instead of a consumer unit. At £15 rather than £70+ it seemed like a good idea, more importantly it is only 75mm square, so will fit into the limited space in the battery compartment under the bonnet. I built a connection board that fixed to the plastic bulkhead connecting the 16A fixed plug directly to the RCD. The hookup module is fixed to the rear plate (shown with all 3 parts temporarily assembled before being installed). This arrangement protects the circuit as close to the inlet as possible ensuring that there is no unprotected 240V cable in the vehicle. 

Once installed the hookup cable fits below the closed bonnet with enough clearance for the cable when closed. The bonnet can be locked down when the cable is connected, preventing unauthorised removal if the vehicle is left unattended.

Whilst having the cab stripped out to install the cables across the cabin floor, I took the opportunity to add more sound deadening. This has made a significant reduction in cabin noise.

Both the 240V cable and the split-charge-relay feed cable have to pass through the shield behind the battery and the bulkhead into the cabin. Ensure that the holes have rubber grommets and abrasion protection where the cables pass through.  The cables can then be routed across the floor of the cabin, under the centre console cover and routed along side the existing cables, to beneath the driver’s seat, where the leisure battery and first power outlet are located.

The little 6 way fuse box for the 12V ancillary circuits is housed at the front of the seat base adjacent to the split-charge-relay module where it can be readily accessed if required. To keep things in the rear clean and tidy the electrical panel is installed into the rear seat base cover. This is a great way to fit the electrical panel as it can be easily unclipped for maintenance or further additions.  A double socket at the rear of the worktop is wired in series with the single socket on the electrical panel again using the high spec cable.

There seem to be as many approaches to T5 camper van home conversions as there are people carrying them out. My approach is to leave the outside of the van as unmodified as possible whilst trying to provide all the facilities required. One thing is for sure no one home conversion van is the same as another.

The Allusionist

The Allusionist Podcast image

The Allusionist is is Helen Zaltman’s podcast about language, how its used, abused, bent broken and spoken, where language came from and how it’s changing. 

Since the first episode ‘Ban the pun’ back in January 2015, Helen has been delivering nuggets of knowledge about language. Now we are up to episode 90 ‘Dear Santa’ where we lear about what happened when 400 letters to Santa were delivered to a flat in New York.  The Allusionist has covered topics such as: lies hidden in dictionaries, emojis, the messiness of English, eponyms, Toki Pona the smallest language in the world, swearing, why the meaning of please changes across the Atlantic, the unofficial dictionary of San Quentin state prison, the etymologies of many words and the occasional place name, brand names and trademarks. The Allusionist is packed with information but delivered gently in a digestible manner.

Each episode also features a random dictionary definition word of the day. The most recent was ‘wayzgoose’ – a printer’s annual dinner or picnic. That word seems alarmingly familiar, but how would I have ever known that?

Indoor fountain

Today didn’t start as expected. The top of the tap on the kitchen sink broke away, turning it from a tap to an indoor fountain.  The copper in the, 8 years old, tap had eroded to the point where it was as thin as foil.

So work started late, delayed by emergency plumbing. It should have been a simple job. I selected a tap online from Screwfix that appeared to be substantially the same as the original, so that there would be the least potential difficulty. It didn’t work out that way.

The new tap is subtly different than the original. To be fair on the whole it appears to be better engineered than the original. Unfortunately it was let down by a slightly deficient fixing bracket and accompanying rubber pad. The fixing bracket reached less than 2/3 the way around the underside of the tap. It proved impossible to tighten the tap firmly in place so that it was fixed solidly to the kitchen sink. Although time consuming, fortunately I was able to reuse the bracket and ‘O’ ring from the old unit to make a secure fixing. Much time was wasted getting the tap fixed firmly to the kitchen sink.

Too thin in the middle to get a spanner onto

The new tails supplied with the tap for connecting it to the water pipes were longer than those of the original tap, so I had to dig out a pipe cutter from the tools in the barn to shorten the copper pipes. The tails on the original tap were push fit, the new tap required a fitting on the pipe to screw the tail onto. So this required a visit to the plumbers merchant to buy a couple of fittings. I now had all the materials to get the job done. The first connection to the hot pipe went fine. However the second fitting although substantially the same had been machined too close to the flats on the body meaning that it wasn’t possible to get a standard spanner in the space available to tighten it. So a second visit to the plumbers merchant was required to find a more sensibly machined fitting. Finally with the correctly manufactured version of the fitting I was able to get the job done.

Because of the design compromise saving a few pence on the fixing bracket and the poor quality control in the manufacturing of the fittings, what should have been a simple job taking less than an hour took more than twice that time. This may be one reason why plumbing is so expensive and also might be a reason that we have such low productivity in the UK.

Core Memory and the Apollo Guidance Computer

Before semiconductor memory, from around 1955 to the mid 1970’s computers used magnetic core memory. This required use of a little magnetic ring for each bit (binary digit) of information. Wires threaded through the rings were used to set the magnetic state of the rings, to clear and to read off the state (1 or 0) of each ring.

When I started training in electrical/electronic engineering I recall seeing examples of core memory in cabinets (like trophy cabinets) in the corridor at the college.

Magnetic core memory

Magnetic Core Memory – CC licensed by

Over the years the memory was miniaturised to a point where manufacturing required the wires to be threaded through the rings by workers using microscopes. The state of the art enabled densities of up to 32 kilobits per cubic foot. Magnetic core memory like that shown in the image above was read write memory.

For applications that required a computer program to be held in a read only memory there was core rope memory. A notable example of core rope memory use was the guidance computer used by the Apollo missions.

Apollo core rope memory

Apollo Core Rope Memory – image from Wikipedia

The core rope memory was more densely packed and required each bit to be threaded as a 1 or a 0.

This MIT video includes a tour of the construction of the Apollo guidance computer where you can see the incredible effort that was required to produce the computer and its rope memory modules.