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Re: New Transformerless Tesla Coil
Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
Sent: Tuesday, September 03, 2002 1:45 AM
Subject: Re: New Transformerless Tesla Coil
> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
> Tesla list wrote:
> > Original poster: "Jolyon Vater Cox by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> > New Transformerless Tesla Coil
> > Today I finished preliminary trial of new transformerless mini-TC built
> > according to Antonio s calculations.
> > Capacitor: 255pF
> > L1: 61 uH
> > L2: 5.482mH 1004 turns of 40SWG ECW on 1 1/8" diameter vitamin pill tube
> This would be mode 9,10, as mine, but the terminal capacitance would
> be just 2.8 pF. The secondary coil alone has probably 2 pF.
> > Topload: 2" diameter plastic disc, coated with metal foil.
I see now...the Medhurst capacitance is 2.014715443 pF which leaves only
0.79518047pF for the topload -that is small!
That would indicate a smaller diameter -a wooden curtain ring covered with
> Did you try to add a breakout point to it?
A thumbtack balanced on the edge to be precise -got small blue streamer from
the point ,not much more -also got smaller streamers/ corona from the sharp
edges of the foil covering at the edges of the disc.
> > So far I have got faint 1/2 inch sparks to grounded wire with copious
> > and ozone generation (are fine RF sparks and corona are better at
> > ozone than bright low-frequency or DC discharges?); the TC is easily
> capable of
> > lighting a 20 Watt fluorescent tube from a distance.
> > Performance-wise, is this to be expected, only while it has been a
> > "miniature" so far, judging from the spark length there is apparently
> > magnification and I am anticipating using the TC with bigger capacitors
> > larger sparks.
> With a larger primary capacitance you can allow for more terminal
> capacitance, and more power available for sparks.
> > Could L1 be better designed -is the Q likely to be low? If I use larger
> > capacitor will a bigger topload bring it back into tune -or will it
> > become untuneable?
> If the ratio between secondary capacitance and the primary capacitance
> is retained, the coil can be tuned for the same mode (in this case,
> menaing that the two resonance frequencies are in a 10/9 ratio and that
> the energy transfer occurs in 5 cycles). For a different mode or a
> different maximum voltage gain one of the coils has to be changed.
> For such low power, wiring losses are probably small, but thick wire
> in L1 always helps. I used 1 mm wire.
SWG 24 is 0.022" which in metric is 0.5588mm
a bit small perhaps?
> > I would be interested to read of experience with transformerless TCs
> > with "mini"coils as I hope to build some easily portable designs capable
> > producing big sparks when running off integral batteries so maximum
> > buck" would be an advantage.
> > And are transformerless TCs likely to be more common in future?
> Their big problem is the association of the voltage gain with the mode.
> High gains are only obtained at the cost of many cycles for energy
> transfer. But is high gain really important if enough power is
How about using an ignition coil next?
> How much voltage is really needed at the output of a Tesla coil?
Hopefully, enough to produce suficient of a "light show" to make a good
scientific talking point!
> Antonio Carlos M. de Queiroz