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RE: Ultra tiny coils!



Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Derek,

Your super tiny coils are really cool!

You say 0.5pF at 140nH for the secondary. Ok, have been ill and have probably been taking too much cold "medicine" ;o) But:

if Fo = 1 / (2 x pi x SQRT(L x C)) = 1 / (2 x pi x SQRT(140e-9 x 500e-15)) = 601e6

I get an Fo frequency of 601MHz!!! That would put them far beyond any frequency I have every heard of for Tesla coils by about 10X!! Does that sound right for the Fo frequency?

What is the primary voltage and BPS rate ( just "roughly")? I should have plenty of power supplies in that range ;-))

I punched it into E-Tesla6 that does do 'mm' range stuff ;-) "Very" rough, but I did get Fo's in the 150MHz range!!

I would be surprised if ordinary poly caps work at all at that frequency... Might want to go to mica...

Very interesting stuff!!

Cheers,

        Terry




At 05:41 PM 2/8/2005, you wrote:

>THOSE ARE SUPER COOL!!! Sell me one!!!!!!!!!!

Sorry, I'm not going to sell you one, that's FAR to easy.

I will of course give you any information you require to make one for
yourself.

The Monopolar?? And Bipolar coils took me about 3 Hours to build each,
(excluding the 2KV PSU)

The Magnifier took me about twice as long, mostly trying to get it some
where in tune. I'm still not happy, but I've run out of small poly caps. So
it's the best I can do with what I have to hand.

The resonant peak of the non-magnifier coils is pretty wide, So tuning is
really easy once you are in the right ballpark. I didn't use any
calculations at all, I'm afraid that most of the TC design programs are a
long way out from reality with such small coils, probably due to stray
inductance and capacitance. When your topload is 0.5pF yes 500fF and your
primary is 140nH, exact measurement becomes tricky.

Have fun building them.. You wont upset the neighbours. You can run them on
your desk. You don't need an RF earth (any bigger than the SLA that powers
them). They cost very little to build and the only dangers are RF burns and
a nasty bite from a 1nF primary cap at about 2Kv

They are almost the perfect TC, if only they gave 10' sparks not 15mm sparks
;-)

Derek