Re: OLTC - Re: Primary resonators with very low L/C ratio

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jolyon Vater Cox by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

The TC advertised by  Edmund Scientific
http://www.scientificsonline-dot-com/ec/Products/Display.cfm?CategoryID=197425
is also a "kicker-coil" i.e. it is an an OLTC using a mechanical breaker.

It is interesting to hear the suggestion of replacing the breaker with an
electronic switch. With regard to this, how about using a blocking
oscillator, with  a feedback winding on the iron cored choke to maintain
oscillation, the TC primary and capacitor being connected in series across
terminals of the switching transistor, MOSFET or IGBT.
The blocking oscillator is electronic analogue of the induction coil, after
all!

Jolyon.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, July 10, 2003 7:23 AM
Subject: OLTC - Re: Primary resonators with very low L/C ratio


 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >
 > Hi,
 >
 > >Higher Fo frequencies really help this!  I was trying to get away with
 > >120BPS (AC resonant line charging) so to get power I needed larger
primary
 > >caps.  Which lead to lower Fo, which lead to very large Lsec, which lead
 > >to High series losses in the secondary...  For higher power coils,
 > >resonate charging (even at 360 BPS three phase) may not be an option.  To
 > >get very high BPS rates we seem to need a type of DC charger like Steve
 > >used.  My OLTC was a little too big for resonant charging and it's 120BPS
 > >limit.  But resonant AC charging does vasty reduce weight and
 > >complexity.  Probably great for a smaller or even "table top" OLTC...
 >
 > I should mention that we could also borrow the idea of the "leak tester"
 > recently discussed.  In a very real way, it is an OLTC too!!  AC line
 > current charges a very small cap and fires with a very high BPS rate (on
 > the AC cycle peaks):
 >
 > http://hot-streamer-dot-com/temp/030707-01.gif
 >
 > Note the 60uS burst spacing:
 >
 > http://hot-streamer-dot-com/temp/030707-02.gif
 >
 > 1 / 60uS = 16666 BPS!!  So instead of using super high primary currents,
 > they use super high BPS!!  One could replace the vibrating contacts with
 > solid state IGBTs or FETs to get lower loss and any BPS rate one could
wish
 > for.  A reasonably simple AC line rectifier charging a BIG filter cap
could
 > be used to provide DC charging to a small cap.
 >
 > I am not sure what cap size the leak testers use, but we can think it
 > through...
 >
 > 20000 BPS, 160Volts firing (rectified AC), 1000 watts....
 >
 > Joules per bang is 1000W / 20000BPS = 0.050J
 >
 > 0.050 = 1/2 x C x 160^2   C == 3.9uF
 >
 > With a 650nF primary you would get 100kHz for Fo.
 >
 > A 100kHz disruptive Tesla coil operating at 1000W and 20,000BPS would be
 > "different"....
 >
 > Something to think about....
 >
 > Cheers,
 >
 >          Terry
 >
 >
 >
 >
 >