Re: Classic coil

Hello Hans,
            You ask.....

> I have been rereading my reprint of Teslas lecture to the
> Institution of Electrical Engineers in London. On page 15, he
> describes a small bipolar coil. Each of the  terminals of the coil
> is connected to a circle, one is 80 cm in diameter, the other is
> 30 cm in diameter. During operation of the coil, the discharges
> between the terminals produce a "luminous sheet" with an area of
> about 0.43 square metre. He states that he in earlier experiments,
> using bigger circles had covered an area of more than one square
> metre. This coil has 2 primaries with 96 turns in each, and two
> secondaries with 260 turns in each. When both the primaries and
> the secondaries are connected in series, this gives a ratio of
> conversion of about 1:2.7.
> It seems that a lot of people are designing coils with much bigger
> conversion ratios (1:67 for a coil with 1000 windings on the
> secondary and 15 on the primary). I would say that Teslas results
> with this coil are quite impressive. Why the big secondaries in
> "modern" coils ?

For a start, the primary energies he was using with those coils was 
rather small compared with our large coils. He could never have got 
the long flaming arcs with the early setups IMO. I am hoping to 
duplicate one of those coils because I am just as interested in the 
results he got with them. The single layer secondaries will allow 
much higher voltage production before breakdown than the bundled 
windings which I think is why he switched to them. The interturn
capacitance in the early coils would have been high and would have 
been the dominating secondary capacitance unlike the single layer 
coils where the capacitance is mostly isotropic. Be interested to 
hear other views on this. Those early coils would make great and 
fairly safe displays too. Definitely on the "have to do" list.