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RE: What now? I'm new

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Hi Ruben:

As to why single-ended coils are more popular than bipolar coils -
here's my take.
1) The formulas and guidelines for secondary/topload resonance are well
established for single-ended coils, but not so for bipolar coils.
2) Adjusting the primary-secondary coupling is easy to do in a
single-ended coil, but with a bipolar coil, you're stuck with whatever
it is.
3) With a single-ended coil, with proper top load design, it's possible
to achieve spark lengths far in excess of the secondary length.  With a
bipolar coil, you're doing well if you can get just the secondary
length, and more probably isn't possible.

A 4kV NST is definitely adequate for a small coil, and much, much better
than any ignition coil.  My minicoil uses a 4kV/20mA NST and I've gotten
16 inches of spark.  See http://www.laushaus.com/tesla/minicoil.htm.

For a how-to guide on building coils, I wrote up an outline of the
design process for building a coil, see
http://www.laushaus.com/tesla/howtodesign.htm. For a very good reference
on how coils work, I like to recommend Richie Burnett's site at
http://www.richieburnett.co.uk/tesla.shtml.  Hmmm, all of the links on
the site seem to be broken and Richie's email address bounces...

Regards, Gary Lau

> Original poster: Ruben van de Ven <ruben@xxxxxxxxx>
> Hi everyone,
> I'm new to this list and new to Tesla Coils in general. So I think I
> should introduce myself first (I don't know if it's common on this
> list to do so.)
> I'm Ruben and 17 years old, I'm from the Netherlands. I'm currently
> doing my sixth and final year of secondary school. In this year I
> have to work on a project (for the Dutch on this list: it is my
> 'profielwerkstuk'). This project has to be good before I can start my
> exams. I was free to pick any subject I liked, after some
> brainstorming I thought Tesla Coils would be a interesting subject,
> and probably a cool new hobby too :-)
> After picking the subject for my project I did some research about
> Tesla Coils: I browsed the web, where I found a huge amount of sites
> discussing Tesla Coils. And of course I found this list.
> Another source of information I found was a man who also made a Tesla
> Coil, using a description from a book about electricity 'for boys'
> from 1955 (for the Dutch: 'Het Jongens Elektriciteitsboek' in a
> chapter named 'Knutselwerkjes')
> This book wasn't an in depth guide into Tesla Coils, it's just a
> short description of how to build one. But the design of it differed
> from the ones that you make, and that I see everywhere on the
> Despite this I choose to work with this design because I saw one
> working and I know the one who made it. And because he never
> calculated anything on the design, I thought it wouldn't be very
> necessary to do so and I can always do it afterwards and point out
> some improvements in my report. That's why I never read a lot about
> TCs before I started building (I know that was a bad choice :-( ) But
> while working on the thing I got some questions and tried to answer
> them. Then I found things like resonance frequencies and I wondered
> what these values would be in my setup.
> Even tough the design differed I filled in some values that might be
> correct in javatc (http://www.classictesla.com/java/javatc.html) and
> I shocked: it was about 80% detuned :-P
> Altough this could be because of the values I filled in, it was
> definitely a high value. When I tried it a second time (with slightly
> different values) it said it was detuned for about 17% (which was
> still marked as high)
> To make it a little more clear to you I scanned some images from the
> http://rvdven.nl/tesla/coils.jpg
> http://rvdven.nl/tesla/setup.jpg
> Short description of the design with the values I'm using between
> Primary:
>      Diameter: 17cm
>      Turns: 10
>      Wire diameter: 2-3mm (2mm)
>      Length: 15 cm
> Secondary:
>      Diameter: 2.5-3 cm (2.5cm)
>      Wire diameter: 0,1 or 0.2 mm (0.2mm)
>      Length: 25 - 30cm (26cm)
> Capacitor (I have none yet):
>     20 plates of glass (13x18cm) with 19 plates of tin (10x20cm of
> which 10x16.5cm is between the glass plates).
>     Estimated thickness of the glass: ~ 3mm
>     I'm not sure about the capacity because I only found formulas and
> constants that used inches while I'm using (centi)meters. But I
> calculated it would be about 0.00428 uF (I hope this is corenct,
> nobody checked it yet.)
> Transformer:
>     The original design uses a ignition coil from a car but I use a
> NST: 4kV 50mA
> As you can see from these images this Coil isn't grounded but has two
> spheres on each end of the secondary coil. I know this will also
> work, the sparks just jump from one sphere to another (given that the
> two spheres are closer to each other than they are in the image.) But
> this design isn't really common (for I haven't seen one yet except
> the one in the book.) There must be a reason why this design isn't
> used that much, and I hope you can give me this.
> Another thing I was wondering is if one of you can point me to a
> guide (or maybe a book) that explains how TCs work and how I should
> design one. Step by step, from easy to hard. Because I found a lot of
> information, most of it is pretty specialized, like: how to design a
> capacitor, it's very usefull if you know how a TC works and what sort
> of capacitor you need, but well, I'm not that type (yet ;-) ) The
> amount of info and the language used a bit overwhelming for a newbie
> like me ;-) And if such a guide/book doesn't exist, then what is the
> best way to learn to design a coil. I can apply the very neat list of
> formulas I found, but I guess there are more things to think about
> than just formulas.
> I was also wondering if I designing/building TCs requires a high
> knowledge on electricity, because here at school we haven't had much
> (only some basic things about electric engines, how to calculate
> parallel/serial voltage/amperage/resistance.
> The last thing I would like you to ask (for now) is why there's
> hardly any information about NST with a lower output than approx.
> 8kV. I have a 4kV/50mA NST which seems quite a high voltage for me,
> but the information I can find is about at least 8kV. I understand
> 8kV means more fun, but why wouldn't 4kV suffice for a small design?
> I'd like to thank you for reading the very long mail, and thanks in
> Ruben van de Ven
> PS. I'm very sorry for the long read, it got a bit longer than I
planned ;-)