"Work in progress"

Colin Dancer


Update (7 April 2008)

Time flies and once again an age has passed without me updating my website.  It just seems there is so much to do that documenting any of it take second place!

MetaSwitch continues to march across the world, (recently boosted by a funding deal with Francisco Partners,) and I continue to play a key architectural role in ensuring it can meet future challenges as well or better than it has met past ones.

My art work with Paul also continues to go from strength to strength and we're currently working on a large show in London in October.  As before my focus is mainly, but not exclusively, on the engineering and science side, and this time includes not only vacuum and high voltage work, but also the production of some multi-ton, fine machined metal sculptures (exactly what they are will have to remain secret until the show opens ;-).

What else to say?

Personally one of the most interesting things which has come up recently is a question of "classification".  With various press-releases and books related to the art work, I'm frequently asked how I want to be described: "Artist", "Scientist", "Physicist", "Engineer"?

As should be obvious from my previous writings I'm against such narrow boxing in of what I or others, do or think.  I strongly feel it restricts people's view of what they or others are capable, and depending on circumstance I'll view the world from all of the above perspectives, sometimes several at once.

Having said that, if  I was really pushed, I suspect I would have to go with Engineer. Yes I formally trained as a physicist, and yes science gives me a unifying framework within which to understand and investigate the world.  However, ultimately, I want to do more than understand the world - I want to go out and build things which change it, and allow us to do things which wouldn't otherwise be possible.  If that doesn't make me an engineer, I don't know what does.

Where does that desire come from?  That's hard to pin down precisely, but there are a number of likely candidates.

I grew up with a father who was a jig and tool designer at W.H. Allens, (a medium to heavy engineering firm that built large diesel engines, steam turbines and the like,)  and from my earliest age remember being fascinated by what he did.  The yearly visits to "the works" left a particular impression on a little lad.  Going round the shop floor there were huge machines for machining parts of multi-MW turbines or engines, ultra-sensitive measuring stations what could quantify micron level surface roughness and massive heat-treatment furnaces belching out heat when the doors opened.  But most particularly I remember being allowed to step inside the crankcase of one of the large diesel engines prior to final assembly.

At home this engagement with engineering continued.  Lego was the starting point, but before long I was "helping" take apart and later put back together car engines.  And I still remember the day I was first allowed to use the Atlas lathe which my father had in the garage.  Taking a raw chunk of metal and shaping it into something precisely the shape you wanted was (and still is) amazing.

The one other things which really sticks in my mind while growing up was a BBC TV children's TV program.  I can't remember the presenter, but the title music was "The Montagues & Capulets" from Prokofiev's Romeo & Juliet, and it was all about great engineers: Brunel, Watt, Stephenson, etc. The program just left me enthralled to the idea of making things which could change the world and I have never lost the love. 

Interestingly, I know of at least three other people who were similarly entranced by that program and have gone on to be engineers of one form or another.

Sadly such programs now seem few and far between, but if anything this just increases my desire to pass on the torch to a younger generation...


Update (23 March 2006)


"A good many times I have been present at gatherings of people who, by the standards of the traditional culture, are thought highly educated and who have with considerable gusto been expressing their incredulity of scientists. Once or twice I have been provoked and have asked the company how many of them could describe the Second Law of Thermodynamics. The response was cold: it was also negative. Yet I was asking something which is the scientific equivalent of: Have you read a work of Shakespeare's?

I now believe that if I had asked an even simpler question -- such as, What do you mean by mass, or acceleration, which is the scientific equivalent of saying, Can you read? -- not more than one in ten of the highly educated would have felt that I was speaking the same language. So the great edifice of modern physics goes up, and the majority of the cleverest people in the western world have about as much insight into it as their neolithic ancestors would have had."

 C.P. Snow


It's a long time since I've done any serious work on my website, but I can only look on this as a good thing, reflecting the fact that I've not had an idle moment.  Even now I have time for no more than a quick update.

At "work" I've helped take my company http://www.dataconnection.com, from straight software, into the world of next generation telecoms http://www.metaswitch.com.  This has required us to progress for a smallish company supplying cutting edge software technology to a range of people from small startups to the major player  (Cisco, IBM, Microsoft. Lucent, HP, Nortel, etc.) to a much larger company, who in addition to what we did before, is now shaping the world of next generation telecommunication.

At "home", my partner and I have emigrated from London to Hampshire and the New Forest.  A huge change of lifestyle, but one that seems so far to be working out well, with free open spaces and a range of different landscapes never more than a minute away.

Through all this, however, I've maintained my passion for the beauty and wonder present in the everyday world, both readily apparent and also hidden unless viewed with the aid of  Science.  Deepening this vision was what drove me to study theoretical physics at Cambridge (and to build some of the "toys" documented below), and is the same thing that makes me want to fight against the "Two Cultures" so accurately (and painfully) captured by C.P. Snow.  

In both the arts and sciences, some areas & disciplines are easier to access and appreciate than others; both are often taught very dryly in schools, and both have their esoteric areas where few will ever venture. Having said that, it is in many ways easier for the uninitiated to get drawn into the arts.  It might take a life time of study to appreciate the full complexity of a Shakespeare tragedy, a Mozart sonata or Michelangelo's David, but for most people, even on the first exposure, there will be at degree of resonance.  If not, then there is a world of other artists and pieces out there fighting to inspire interest.

With the sciences things are different.  Many of the world's great wonders go overlooked, reduced to mere technologies contained in everyday devices.  Viewed in the right way fabulous things can still be seen, but the degree of instant engagement is often similar to that of a great musical work perverted into the muzak you hear in a lift.

This is not only sad, but is also dangerous. Unless people have a basic understanding of how the world works, and unless they learn how to weigh evidence and apply Occam's Razor, they leave themselves (in this increasingly technological world) at the mercy of others.  Humanity as a whole is facing some critical challenges and people need to be able to make sound judgments for themselves, not just be blindly guided by politicians or pressure groups...

Anyway, as luck would have it, about 3 years ago I met a very talented artist, Paul Fryer www.paulfryer.net . We hit it off straight away, and have since been working on a number of artistic pieces which bridge the gap between science and art. I'm enjoying the collaboration hugely, but am also hopeful that the resonance and visceral response which art can generate will inspire a wider audience to learn more about science.

The launch of our first big piece will be in mid-April and I'll hopefully find time to provide details of some of the underlying science after that.  In the meantime, I'll just say that we've found something much more interesting to do with the power required to boil a kettle!


(I was struck while writing the above text by the contrast with the earlier material which I've left below.  I think the best explanation is that the new material is trying to put over some serious thoughts to a broad audience, whereas the older material is just casual chat on a recreational subject to fellow techies C.) 


Update (16 August 2003)

Lots going on, but not much Tesla related.  My current top project is an evolution of the BatBlaster audio slalom device for vision impaired water skiers. It's provisionally called the LazerBlazer and the system outline can be found here (~500K PDF doc with hi-definition photos) or here (~100K PDF docs with lo-definition photos for faster loading).

Update (8 September 2001)

I've recently got a 3KVA mini-pig + ballast so larger sparks are on the way.  I'm also working on an MW54 jet engine and a Stirling engine powered by the heat of your hand.  

The later is particularly pleasing and I would thoroughly recommend looking at the engines on the Exergia website http://www.exergia.de

Update (28 May 2001)

Had a great day at Corby.  I'll update this page properly later, but for now here are some pics: Pictures from Corby 2001

Update (29 October 2000)

I ran the coil at full power last night at the Winter Teslathon in Cambridge.  After slight retuning to allow for the lack of a garage ceiling I was consistently getting 37" strikes to the building wall!  

Now all I need is that spun toroid...

Update (13 October 2000)

Lots has happened since my last update.  

  • I've built a new MMC using a modular design and RS rather than LRC capacitors.

  • My RSG has been upgraded to have a thicker disk, larger electrodes and a more powerful motor.

  • The strobe circuit has been tweaked to give a more solid lock.

  • I've clipped the leads connecting the MOVs into my NST filter circuit, as it turned out that I hadn't rated them correctly and they were stopping resonant charging of my tank capacitor.

  • I've temporarily increased the topload size by stacking  another ducting toroid on top (I've got a spun aluminium toroid on order).

  • My control box is finished including safety interlocks.

  • Using experimentation and the PSpice schematics on Richie Burnett's site I've phased my RSG for optimum spark length.

Taken together these improvements now mean that I can get good solid 24" discharges, but still only at 75% on the variac!

For now I've just updated the strobe schematic and included a new section listing some of my favourite Tesla coil links, but I should hopefully soon have some pictures of the new components and the coil in operation. 

Update (14 July 2000)

I've now included details of the zero-crossing strobe I'm using for adjustment of my RSG.

Update (3rd July 2000)

I've just fired my coil up for the first time tonight and it worked like a treat!  

With nothing more than rough scope tuning, and no adjustment of the spark gap phase I got 16" to an earthed target when at 65% on the variac.  I daren't currently go any higher as the arcs are bound to hit the low ceiling and thence the house wiring.

There's obviously a lot of tweaking to do in terms of primary tap point and gap phase, but I'm frankly quite pleased with 16" for a first effort.  I was particularly pleased with the rotary gap, which lit at only 10-15% on the variac, and gave nice controllable output from small 1" purple corona to 16" white hot arcs.  


My first serious Tesla coil, at Corby 2001.


Basic parameters

15 turn 8mm copper pipe primary (designed to tap at 10 turns)

5" x 23" secondary wound with 0.5mm wire

12" x 5" top-load made from dryer duct

14nF 10KVrms MMC (hanging below the center of the coil)

200bps Sync RSG made from a grinder

10KV 50mA NST

RC + MOV protection circuit



Construction Details

(Pictures are thumbnails.)

The primary is supported by 9 bars made from cable conduit.  The holes were drilled with the aid of a jig made using conduit clips and a nail to index one hole off the next.

Heavy duty cable from an old UPS is attached to the primary using a modified fuse holder.

The close-up also shows the cable conduit supports, and their attachment to the base using PCB standoffs.

The topload is 5" aluminium dryer duct formed round two 7" pie tins.  The two ends of the duct were attached to each other by stitching with cotton thread.

The stand-off (like the base legs) are made from PVC pipe fittings.

The secondary coil was wound on a PVC form intended to be used in a ventilation system.

The wire was placed at 48 T.P.I. with the aid of the lathe's screw cutting gearbox. 

It was given multiple coats of polyurethane varnish, each being allowed to dry with the form rotating. This gave a very smooth and even finished.

The top of the secondary is finished with an HDPE disk made from a cutting board, turned up and epoxied in place.  

Glued to the centre is the cap from a waste pipe access port.  This provides an easy means of attaching the top-load standoff.

The strike-rail is also 8mm copper pipe, flattened and attached to the supports using bolts.
Two views of the MMC tank capacitor.  It is made from three strings of 9 x 0.047uF 1500V poly capacitors from LCR.  
The capacitors are mounted on both sides of a small HDPE cutting board with 10Meg bleed resistors to limit the time the capacitor will hold a dangerous charge.
My 3000RPM 200 bps synchronous RSG, made using a small bench grinder from B&Q. 
The stationary electrodes are made from M6 brass machine screws, screwed through tapped brass bars, which in turn are bolted to Tufnol supports.

The disk is made from G10 PCB, with 4 flying electrodes made from M4 brass machine screws.

The electrodes are connected using copper track left on the back of the disk.
The motor was made synchronous by machining two flats on the rotor.

To get a good lock the flats needed to be 20mm wide.

(Note the rotor bars showing through the laminations of the core.)

To get the disk to run true the grinding wheel washers needed to be trued up.

The NST protection filter combines an RC filter with MOVs to clamp the voltage across the transformer.

The Colchester Bantam lathe which made the making of the coil much easier than might otherwise have been the case.

(Note, the screwcutting gearbox is currently removed for refurbishment.)

sync_strobe.jpg (28588 bytes) To help adjust my RSG, I've adapted a simple kit from Maplin to provide a 50Hz strobe synchronized to the zero-crossing of the mains.
Favourite Tesla Coil Links

Finn Hammer's homepage


A true craftsman who has done some wonderful work.

Richie Burnett's homepage


Without doubt the best Tesla coil theory page I have found.

The Pupman archive The place every new Tesla coil builder should start.

Final Words...

If you've any questions, opinions or advice on my coils or webpage, please feel free to contact me.



Before even thinking about building a coil, please read the safety information on the Tesla Coil mailing list site.



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