Re: Charging inductors for resonant charging

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

Original poster: "S & J Young" <youngs-at-konnections-dot-net> 

Jim,

The SPDT TSG was also my goal.  I tried it but could not prevent both gaps
from firing at the same time, which results in frighteningly loud filter cap
discharges, pegging ammeters, and current limited only by the resistance of
the charging reactor and one's ability to quickly shut off power to the DC
supply!  If you can get it to work smoothly like a SPDT RSG, I would
appreciate learning how you did it.  (Sorry, but even your pipe cap TSG
design, good as it is, didn't prevent both gaps from simultaneously firing.)

I also tried 4 TSGs in an H-Bridge configuration (no charging reactor) from
a very lethal stiff DC supply with even worse results (deafening BANGS from
shorts across the power supply because all 4 gaps would fire).  But a DPDT
RSG version of it worked great.  I abandoned it out of fear of and respect
for the 6 mFd 16 KV low ESR filter cap in the DC supply.

The SPDT RSG version doesn't seem to be noticeably more lossy than a SPST,
and it has the advantage of not needing the large charging reactor.  Both
the charging and discharging impulses are through the primary which may help
reduce losses.  I can do break rates down to 1 BPS with it no sweat, but had
to use a 50 Henry reactor to go down to 150 BPS without power arcing in a
normal single RSG configuration.  The disadvantage is it doesn't seem to
lend itself to the use of TSGs.

--Steve Young


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, January 29, 2004 11:01 PM
Subject: Re: Charging inductors for resonant charging


 > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Thursday, January 29, 2004 8:30 PM
 > Subject: Re: Charging inductors for resonant charging
 >
 >
 >  > Original poster: "S & J Young" <youngs-at-konnections-dot-net>
 >  >
 >  > Jim,
 >  > I have used the secondaries of MOTs successfully.  MOTs range from 6 to
 > 20+
 >  > Henry, so you may have to measure a few of them to get the value you
want.
 >  > If you want to control saturation, it only takes a few minutes to
hacksaw
 >  > through the core welds and put a small air gap in the magnetic path
(e.g.
 > a
 >  > few layers of masking tape).  I didn't bother to remove the magnetic
 > shunts.
 >  >
 >  > I don't know what your end use is, but if it is a TC, consider using a
RSG
 >  > configured as a SPDT switch.  This is used to charge the tank cap, then
 >  > discharge it through the primary.  Your power supply is totally
 > disconnected
 >  > from the tank circuit as it discharges.  In this configuration, the
 > charging
 >  > reactor only needs to be around 0.2 Henry and can easily be made with a
 > few
 >  > air coil solenoids in series to withstand the voltage.
 >
 >
 > The application is a triggered spark gap TC (actually, more than one, fed
 > from a large, stiff (and mindbendingly lethal) DC supply).  Interesting
 > idea, though of SPDT configuration. Two triggered gaps, one to charge the
 > tank, one to discharge it.  Hmmm.. elegant, albeit probably a bit lossy,
but
 > heck, what's a few kW.
 >
 >  > --Steve Y.
 >  > .