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March 11, 2008

An Engineer in Wonderland: What do volt.seconds look like?

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Coulombs I can do.

They quantify charge and are proportional to the number of electrons shifted, and not too difficult to visualise as electrons are real little round things.

In a circuit they are being pushed up a gradient against their natural tendency to stay still, if you get my meaning.

Coulombs get an outing in CΔV=IT, that particularly handy formula for sizing reservoir and de-coupling capacitors.

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Posted by Alun Williams on March 11, 2008 1:29 PM | | Comments (4) | TrackBacks (0)

March 13, 2008

An Engineer in Wonderland: Green chandeliers don't sparkle

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I was speaking to someone from a big heritage organisation the other day, and learned that there is a hunt for ways to cut the power consumption of chandeliers.

These, apparently, were usually designed specifically for incandescent bulbs, or have been converted to them from either candles or gas.

At 10 lm/W, incandescent bulbs are not very power efficient, but they weigh very little and most importantly their optical output allows the chandelier to sparkle.

LED and compact fluorescent bulb replacements have been tried, but they failed the all-important sparkle test.

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Posted by Alun Williams on March 13, 2008 8:39 AM | | Comments (4) | TrackBacks (0)

March 17, 2008

An Engineer in Wonderland - There aren't 'arf some clever...

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Occasionally I get that I-wish-I'd-thought-of-that feeling.

And these cunning little tins produce exactly that.

The lid is firmly attached until by pressing the centre of the lid, the lid suddenly snaps down.
It moves a millimetre or so and, by distortions in the metal I never expect to understand, the clips around the edge spring apart allowing the lid to be lifted away.

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Posted by Alun Williams on March 17, 2008 8:32 AM | | Comments (1) | TrackBacks (0)

March 18, 2008

An Engineer in Wonderland - Gravia

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Civil engineers that I know are inclined to get a bit grumpy about architects, on account of their artistic flair getting in the way of actually designing buildings that work.

But it looks like one talented architectural student has learned his lesson in practicality early, and will probably check with the engineers before he releases any real designs.

US Virginia Tech student Clay Moulton designed the stunning Gravia concept - a gravity-powered floor lamp.

The 1.2m tall device runs somewhat like a grandfather clock, with just over 20kg of brass weights that descend slowly - in this case running a generator.

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Posted by Alun Williams on March 18, 2008 4:48 PM | | Comments (0) | TrackBacks (0)

March 19, 2008

An Engineer in Wonderland - Arthur C Clarke

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Arthur C Clarke died this morning.

Apart from the science fiction, he should be remembered for the article he wrote describing his idea for a global communication system based on three satellites in fixed positions spaced evenly around the globe.

In this, so one of the editors of Wireless World told me, he described the necessary technology so thoroughly that the article was used years later to defeat an attempt to patent geostationary satellites in the US.

'Alice'

(Pictured: Geostationary communication satellite Galaxy 15 from US firm Orbital. With a launch mass of 1.7tonnes, it is designed to operate for 15 years.)

Posted by Alun Williams on March 19, 2008 2:02 PM | | Comments (1) | TrackBacks (0)

March 20, 2008

An Engineer in Wonderland - My uncle, motorbikes, and lead-free solder

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It was a wistful day in the home workshop yesterday when I got down to the last bit of solder on the only reel I have ever owned.

I have always enjoyed making things, and this particular reel was given to me by my uncle years and years ago when I was a young teenager itching to try electronics.

The last few centimetres went soldering a diode into the wiring loom of my motorbike, which is fitting because on motorbikes is how I remember my uncle.

Now I have a dilemma.

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Posted by Alun Williams on March 20, 2008 8:02 AM | | Comments (3) | TrackBacks (0)

March 24, 2008

An Engineer in Wonderland - Nano-printing by explosive

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You can get a bit blasé about achievements at the various Fraunhofer Institutes in Germany. They are always doing clever things - take a look the ethylene sensor here: Infra-red sensor tunes fruit ripening

But its Institute for Chemical Technology has excelled itself by proving that explosive blasting in miniature can be used to make tools for hologram production.

I have seen explosive forming before - as a way of forcing aluminium sheet into moulds - but nothing with resolution "in the two-figure nanometre range" that Fraunhofer is claiming.

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Posted by Alun Williams on March 24, 2008 9:10 AM | | Comments (0) | TrackBacks (0)

March 31, 2008

An Engineer in Wonderland - Free LED lighting backgrounder

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Webinars are a bit of a lottery, but I came across an excellent one from National Semiconductor.

It is about white power LEDs, and includes a fair amount of detail on colour rendering.

Most of the information is generic, although Lumileds - a sponsor of the webinar - is the only LED maker featured.

I particularly liked the bit explaining why green leaves look grey when illuminated by 'white' light made using a balance of red, green and blue LEDs.

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Posted by Alun Williams on March 31, 2008 8:45 AM | | Comments (0) | TrackBacks (0)

April 1, 2008

An Engineer in Wonderland - bikes and loo brushes

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Generally I am amazed at how good stuff is.

For example, this weekend I spent a couple of hours fixing up a friend's cheap bicycle. It must have cost under £200, had been left out in the rain, and wasn't working too well. With a few careful squirts of oil, and a bit of spanner work, it was a proper bike.

Not a thoroughbred, but a vastly better bike than one you would have bought 20 years ago for a similar inflation-adjusted sum.

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Posted by Alun Williams on April 1, 2008 9:10 AM | | Comments (1) | TrackBacks (0)

April 8, 2008

An engineer in wonderland - Foxes and charging bloody Li ion batteries

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I once saw an artic fox in Norway.

The beautiful fluffy white creature trotted up and sat down only a few metres away, not at all fussed by a couple of cyclists sitting eating sandwiches.

Only I didn't get a photo because my camera had run out of film.

So when I bought a digital camera, I bought one that took easily available AA cells so that I could not run out of film or batteries.

And that worked well for a long time, until I wanted a camera with more than a 3x zoom.

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Posted by Alun Williams on April 8, 2008 11:00 AM | | Comments (2) | TrackBacks (0)

April 10, 2008

An Engineer in Wonderland - Why they won't let me be a mechanical engineer

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Given the problem:

How do you pump water into a boiler using only steam pressure from that boiler?

I would come up with some sort of piston-based steam engine connected to a piston-based water pump.

Which identifies me as a thermodynamic dunce - as a much cleverer no-moving-parts answer was invented 150 years ago; which I came across in a book on steam engine technology.

Basic thermodynamic theory flourished in the mid-19th century, which puzzled me until Richard Wilson, editor of Electronics Weekly, explained it thus: "Because they had big brains and nothing else to think about."

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Posted by Alun Williams on April 10, 2008 2:56 PM | | Comments (0) | TrackBacks (0)

April 17, 2008

An Engineer in Wonderland - A blog In praise of Jim Williams

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There are times when you read an article and realise the author has got right down to the bottom of the subject.

One such encyclopaedic treatise I came across a few years ago was a Linear Technology application note: 'Ultracompact LCD Backlight Inverters - A Svelte Beast Cuts High Voltage Down to Size' by Jim Williams.

I had never even heard of piezoelectric transformers when I started reading it, but by the end I could see their potential and knew exactly how I would try driving one if I ever had to feed a compact fluorescent lamp.

Jim Williams seems to have a knack of writing thorough applications notes - which I first came across in an old lab copy of a Linear Tech app note book.

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Posted by Alun Williams on April 17, 2008 3:39 PM | | Comments (1) | TrackBacks (0)

April 25, 2008

An Engineer in Wonderland - Domestic wiring madness?

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Years of experience, and quite probably many tragedies, have made the UK wiring regulations what they are - good, sensible rules - albeit written in a somewhat impenetrable form.

For all the right reasons, no power sockets or wall-mounted switches are allowed in bathrooms, and light fittings near the bath, shower and hand basin must be special water resisting types.

However, what I find a little nuts is that there seem to be no special rules for the room immediately under the bathroom - normally the kitchen.

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Posted by Alun Williams on April 25, 2008 3:35 PM | | Comments (12) | TrackBacks (0)

April 30, 2008

An Engineer in Wonderland - Slug-O-Cutor

Like many people last year, I had a slug infestation.

Now, I claim not to be a cruel person, but the little buggers were eating just about everything in the garden and I wanted them dead.

As I am not keen on the lingering death induced by slug pellets, or their effect on the food chain, an electronic slug-o-cutor had to be the answer.

I couldn't buy one, so one had to be invented.

At this point, don't get too excited, because I never did build anything for it seems that digging over most of the plot in preparation for laying a lawn also kills slugs.

But I enjoyed the design challenge, and this was my thinking.

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Posted by Robert Kotevski on April 30, 2008 8:00 AM | | Comments (10) | TrackBacks (0)

May 7, 2008

An Engineer in Wonderland - Wonderful generators in Freeplay radios

Freeplay wind-up radio

The generators in Freeplay radios have moved on a great deal from the original Trevor Bayliss design, and look quite superb.

I noticed this when squinting through the blue tinted plastic of a Freeplay EyeMax (pictured). [Recently featured in a Gadget Freak competition, btw - Ed.]

Bayliss' original leap of imagination was that a modern wind-up radio was possible, and he followed this up by developing one - coming up with a design that stored power in a spring.

The spring unwound through a set of gears that spun a small DC motor operating as a generator.

Effectively a Mark II, the next version was a better shape to grip when winding, and added a rather neat power-saving touch - a transistor shorted out the motor when its reservoir capacitor was full - which almost stopped the motor and effectively froze the spring until power was next needed.

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Posted by Alun Williams on May 7, 2008 1:31 PM | | Comments (0) | TrackBacks (0)

May 14, 2008

An Engineer in Wonderland - Henry Moore, engineering, and art

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In a break from working out how to stabilise mountain sides, Imperial College London was recently called in to rescue Henry Moore's Arch - a not unpleasant six metre tall stone sculpture that was taken down from a London park in 1996 because it was on the verge of falling down.

Despite its ultra-modern image, Imperial still has wonderful big materials testing machines lurking in its basements, and a startling amount of expertise in things rock.

It found that the sculpture's unusual shape combined with the poor location of the joints between its seven pieces, and the use of travertine which is a brittle stone, conspired to make it unstable.

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Posted by Alun Williams on May 14, 2008 1:12 PM | | Comments (1) | TrackBacks (0)

May 16, 2008

An Engineer in Wonderland - Loo roll holders, and a loo brush reprise

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Not that I am obsessed with loos, but I do like stuff that works well.

The traditional commercial loo roll holder has a large roll of paper whose momentum means it needs careful handling if the paper is not to break early, or the loose end is not to disappear from view.

This rather nice design, from Paperstream, still holds loads of paper, but in conventional low-momentum rolls.


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Posted by Alun Williams on May 16, 2008 2:55 PM | | Comments (0) | TrackBacks (0)

May 19, 2008

An Engineer in Wonderland - You can't just turn off CERN

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I have just read an article by those folk at the US Fermilab in their magazine Symmetry. They are collaborating with European physicists at the Large Hadron Collider (LHC) in CERN, Switzerland, and some of the numbers they reveal are mind boggling.

Apparently, when everyone goes home at night, they can't just turn the LHC off as it has two proton beams travelling around in opposite directions, each with as much energy as a train doing 120 miles an hour.

Letting them go off at a tangent would result in a hole "tens of metres long in any material"

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Posted by Alun Williams on May 19, 2008 12:37 PM | | Comments (0) | TrackBacks (0)

May 21, 2008

An Engineer in Wonderland - Teamwork, roofs and solar heating

w-b Worcester Bosch.jpgI spent 13 hours up ladders yesterday, acting as a plumber's mate fitting solar thermal panels. It was the first time for all three of us, which is why it took such a long time, but it was very satisfying.

Firstly because even with no liquid in, the panels were happily generating hot air from their outlet pipes. I know this shouldn't surprise me as I understand the theory, but it was nice to feel it in action.

Secondly, it was good to work in a team where everyone is competent and pulling in the same direction. No egos, no shouting, just dedication to doing a good job.

And lastly because the panels (2 x Greenskies FKC-1S solar panel, pictured) and fitting kit (Roof integrated FKI5 portrait basic 2 coll tile) supplied by the manufacturer, Worcester Bosch, were first class.

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Posted by Alun Williams on May 21, 2008 11:40 AM | | Comments (0) | TrackBacks (0)

May 30, 2008

An Engineer in Wonderland - Victorians, Eurostar and architects

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I travelled on Eurostar from St Pancras Station for the first time, and I am impressed, and also slightly disappointed.

I used to leave from Waterloo, and it was always a bit of an embarrassment when returning from Paris or Brussels as the mighty train dropped from 180mph in continental Europe to about 20mph as it bumped and clattered across Kent and crept into London.

Incidentally, I am told that the power electronics in Eurostar has its roots in the UK's Advanced Passenger Train - That ill-fated train which ultimately failed because the ultra-light drive mechanics that allowed it to run fast on standard rails was a technological step too far for its gearbox oil and drive shafts.

Allegedly, the APT had another successful spin-off - its tilting mechanism may be the one used in the Alstom-built Pendolinos that ply the West Coast mainline.

If anyone can confirm or disprove the above 'facts', I would be interested.  

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Posted by Robert Kotevski on May 30, 2008 2:28 PM | | Comments (1) | TrackBacks (0)

June 2, 2008

An Engineer in Wonderland - Arguing about solar heating

w-b solar panel boiler_type_6.jpgThe solar panels are up, and on a not-very-sunny day got the water in the domestic cylinder up from 22 to 40 degrees, an 18°C rise, requiring 20°C of additional heating to get the cylinder to its operating temperature.

The temperature rise in the cylinder would have been greater, as the panel exit temperature was 61°C, but the long feed pipes from the loft to the cylinder are not yet insulated.

But it got me thinking.

At the moment, the two panels are plumbed in parallel. 

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Posted by Alun Williams on June 2, 2008 10:23 AM | | Comments (4) | TrackBacks (0)

June 23, 2008

An Engineer in Wonderland: Alice on the road to Damascus - Am I wrong to doubt power floors?

victoria line.jpgA couple of years ago the BBC carried a report that the "34,000 commuters who pass through Victoria underground station at rush hour, for example, could theoretically generate enough energy to power 6,500 LED light fittings."

Being generous, allowing a fitting to be a single 5mm LED taking 70mW, that is 445W.

I use Victoria underground station, and although I haven't timed it, I suspect I spend about three minutes walking in it (and many more standing around on its platforms) each time I use it, so if that is true of everyone, there will be 34,000 x 3/60 or 1,700 people in it at any on time.

So 445W between 1,700 moving people is 0.26W each.

Hmm, not too bad so far.

Will anyone notice this?

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Posted by Alun Williams on June 23, 2008 3:51 PM | | Comments (3) | TrackBacks (0)

June 26, 2008

An engineer in wonderland - Designers I have known

lathe at night.jpgI have worked with excellent engineers.

On the desk of one I shall call Simon, was a piece of lathe work he produced as a teenager.

It was in three parts, one brass, one aluminium and one steel.

He had bored the brass cylinder, and cut a fine thread on the outside of one end onto which screwed the aluminium in the form of an end cap.

Together, the aluminium and the brass part formed a blind hole about 40mm across and 30 deep which sat on the desk like a cup.

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Posted by Alun Williams on June 26, 2008 4:04 PM | | Comments (0) | TrackBacks (0)

June 27, 2008

An Engineer in Wonderland - LED candles

led candles.jpgA friend showed me these amazing little things from Philips.

Basically, they are fake night-light-in-a-glasses based on LEDs. I didn't put one next to the real thing, but on their own or in bunches they flicker very realistically.

As far as I can see, there are only two small LEDs in each, plus a rechargeable battery and some kind of pseudorandom driver for the emitters.

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Posted by Alun Williams on June 27, 2008 2:22 PM | | Comments (2) | TrackBacks (0)

June 30, 2008

An Engineer in Wonderland - The best tin opener?

p38add.jpgOne of the neatest designs I have ever come across is the military folding tin opener.

I am talking about the little rectangular ones with a hinged tooth, sometimes known as P-38s.
For a few grammes of steel, you get something that opens food containers in under 10s, and is far less dangerous than the ram-in-and-chew-your-way-around portable type that leaves a nasty sharp edge on the container.

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Posted by Alun Williams on June 30, 2008 9:02 AM | | Comments (0) | TrackBacks (0)

July 1, 2008

An Engineer in Wonderland - Land speed records, and steam

SSC.JPGI am never going to forget those pictures of Thrust SSC with the shockwave angling back across the desert.

There is something magnificent and a little bit mad about land speed records.

A record attempt takes a lot of engineering.

Gone are the days when someone bolted a huge engine into a little tiny car and then just pointed it down a runway.

Which is a good thing in my opinion because a lot of talented people have ended up dead because they took too many chances, or didn't see enough of the potential problems.

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Posted by Alun Williams on July 1, 2008 3:33 PM | | Comments (0) | TrackBacks (0)

July 3, 2008

An Engineer in Wonderland - Waterwheels

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I have always had a soft spot for waterwheels, but like many things historic, thought they were all much of a muchness.

But Windmills and Waterwheels Explained by Stan Yorke has changed all that for me.

So fascinating I find difficult to put down, it has taught me that there were innovations in waterwheel design throughout their history.

For example, for thousands of years the central axle of water wheels carried power into the mill building.

Then some bright spark realised that you can bolt a great big gear to the wheel, and mesh it with a little gear to take power into the building.

The new drive shaft runs faster - so less gearing up is needed inside - and can be thinner because it is transmitting less torque.

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Posted by Alun Williams on July 3, 2008 8:12 AM | | Comments (2) | TrackBacks (0)

July 7, 2008

An Engineer in Wonderland - Cunning power transmission

wheal martyn.jpgThinking about waterwheels the other day reminded me of a power transmission scheme that I happened across while cycling in Cornwall.

Question:
Given a waterwheel on one side of a hill, and a pump on the other, how do you power one from the other?

Now I could come up with all sorts of schemes involving pulleys and chains, hydraulic pressure, and rotating shafts in tunnels.

None of which are as simple and elegant as one at the Wheal Martyn china clay mine (pictured).

No longer in use, although the mine is still active, the power is transmitted by a series of linked horizontal rods, each running on a couple of rollers.

Connected to a crank on the waterwheel, which does still work, the rods oscillate back and forth a metre or so.
 

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Posted by Alun Williams on July 7, 2008 8:01 AM | | Comments (3) | TrackBacks (0)

July 24, 2008

An Engineer in Wonderland - portable toilets

portable toilets.jpgThere is something wonderful about portable toilets.

Not only because they are the difference between privacy and bearing your bum in public, but because the construction is so neat.

There are a few simple plastic mouldings, which I assume are vacuum or pressure formed from flat sheets on a single-side mould.

Then there are pop rivets

A few bent bits of metal for fittings

A hand pump

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Posted by Alun Williams on July 24, 2008 8:53 AM | | Comments (0) | TrackBacks (0)

An Engineer in Wonderland - Madness in Battersea

30jul08BatterseaEM1 small.JPGBattersea power station in London, with its chimney at each corner, is an icon - not least for having made it onto the cover of Pink Floyd's Animals album and having been designed by Sir Giles Gilbert Scott - he of red telephone box fame.

There are plenty of other reasons to love the place, including a rather fine art-deco interior and it once having been part of a large CHP (combined heat and power) scheme that heated a housing development on the other side of the Thames.

But an odd thing is going down at the site, which has been derelict for years and is prime building land.

30jul08BatterseaEM2.JPGThe main building is well worth saving as is has two beautifully decorated cathedral-like spaces solidly built in brick - it is the biggest brick building in Europe.

However, those famous chimneys have to come down. They are fatally riddled with cracks - the result of an incomplete understanding of reinforced concrete when they were built.

Here comes the madness:

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Posted by Alun Williams on July 24, 2008 11:53 AM | | Comments (5) | TrackBacks (0)

July 29, 2008

An Engineer in Wonderland - A car alternator surprise

AliceAlterator2.JPGI was asked to have a look at a car that was not charging properly yesterday.

It is a kit car based on a Renault 6.

When I measured the battery, it was charging at about 13.8V - with and without the lights on. This is a bit on the low side for a car, but acceptable.

As the owner said it had not been charging at all, I thought I would pull the alternator brushes, just in case they were worn.

So we took the thing off, a SEV Marchal unit, and dismantled the back end where the brushes normally are.

No brushes. 

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Posted by Alun Williams on July 29, 2008 12:26 PM | | Comments (5) | TrackBacks (0)

July 31, 2008

An Engineer in Wonderland - Alice-machine interface

06aug08RadioOld2.JPGThese days, I own a car.

And as I have a car, I feel the need for Radio 4 and music.

So a year or so ago I replaced the standard worn cassette-radio with a CD-radio (left).

It cost £50ish from Lidl, and its major selling point was that it also played USB sticks and SD cards.

Incidentally, the necessary fitting kits, bought from Halfords, to convert Ford's non-standard radio orifice to fit a DIN standard radio cost almost as much as the new radio - thanks Ford.

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Posted by Alun Williams on July 31, 2008 3:31 PM | | Comments (1) | TrackBacks (0)

August 4, 2008

An Engineer in Wonderland - Roller clutches

roller clutch.jpgI am currently driving to work as my bicycle has a fault which is in danger of becoming a saga.

A long long time ago far far away, I bought a back wheel.

And within the back wheel was a novel freewheel mechanism based on a roller clutch rather than the standard pawl system that has served cycling well for a century.

A roller clutch is a bit like a roller bearing: It has two concentric cylinders, one inside the other, and between them are metal rollers.

The cunning bit is that, unlike a roller bearing, ramps cut into the surface of one of the cylinders - one ramp per roller- make the gap between the cylinders vary slightly above and below the diameter of a roller.

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Posted by Alun Williams on August 4, 2008 4:45 PM | | Comments (1) | TrackBacks (0)

August 8, 2008

An Engineer in Wonderland - Big Science