Re: The OLTC II lives!

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Steve,

At 08:50 AM 1/27/2004, you wrote:
>Hi all,
>
>I have just got my new OLTC working. Here are some pics:
>
>http://www.scopeboy-dot-com/tesla/bigbang.jpg
>A single shot
>
>http://www.scopeboy-dot-com/tesla/ol2sparks1.jpg
>2kW input at 500bps. 48" streamers to air.

Of course, your coil's performance here leaves all the rest of use OLTCers 
in the dust :-))

I see you have 2kW doing 48 inch streamers.  Since the OLTC is a disruptive 
coil, I would think John 's formula would somehow apply:

spark length (inches) = 1.7*sqrt input power (wallplug watts)

I was just curious if your coil seems to match that equation?  At first it 
seems not to, but you have the charging circuit in there which may confuse 
things.


>http://www.scopeboy-dot-com/tesla/ol2sparks2.jpg
>Same, but shorter exposure
>
>Technical details: The OLTC II uses a 10" single turn primary, 10" x 30"
>secondary with 1700 turns, 24" x 8" toroid, 15uF 1kV MMC tank cap, and two
>1.2kV 600A Powerex IGBT bricks in parallel for a "spark gap". The peak
>primary current is around 5kA, but the bricks don't seem to mind.
>
>The tank cap is charged off the 240V AC line, via a voltage doubling
>rectifier, filter cap bank, and DC resonant charging choke/diode. Thyristors
>were used in place of diodes in the doubler, so the charging voltage can be
>adjusted from zero to over 1kV.
>
>At the moment I haven't dared to use charging voltages greater than about
>800V, but eventually I hope to crank it up to 1kV and get even bigger sparks
>:-0

:-))  I still have the two other IGBTs if you need them!


>Read about the project in gruesome detail on
>http://www.scopeboy-dot-com/tesla/
>
>Thanks to Terry Fritz who donated two IGBT bricks and a pile of CDE caps to
>this project, and also thought up the OLTC concept in the first place.

Thanks for making it work ;-)))

Cheers,

         Terry



>Steve Conner