The OLTC II lives!

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

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

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.

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

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.

Steve Conner