RE: New TC Topology

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

Original poster: "Stephen Mathieson" <s.mathieson-at-charter-dot-net> 

Use a good ground and attach a scope to a second ground to time the
reflected pulses (from China?) If you fire your coil to coincide with the
reflected pulses they will get bigger and bigger. That's what Tesla did in
Colorado Springs. Beware, your neighbors may not take kindly to lightning
coming out of their water faucets!

Stephen A. Mathieson

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, September 25, 2003 10:37 PM
To: tesla-at-pupman-dot-com
Subject: New TC Topology

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

List,

I tried a different DC resonant charger TC topology - one I haven't seen on
the list before.  It worked well.

My DC supply feeds a reactor and deQing diode as usual.  This feeds a RSG
acting like a SPDT switch.  In the first electrode presentation, it charges
the tank cap in series with the primary.  In the next electrode
presentation, the second gap is across the tank circuit, creating the main
bang.  The cycle repeats, and the DC supply is completely isolated during
the main bangs.

The advantage is that the DC supply never sees a short across its output, so
it can't power arc.  Very nice!  The spark in the gap that charges the tank
circuit is much less intense as compared to the discharge gap.

Another advantage is that the reactor can be considerably smaller than
usual. It must be large enough to limit the charging current to the tank
cap, but not so large that the cap doesn't finish charging before the
electrodes move apart.  I tried 200 mH and it works like a champ.  Mine is
made of four 50 mH sections to distribute the peak voltage across it.  I
needed about 50 H (3 MOT secondaries in series) for the normal topology.

A third advantage is the BPS can be as slow as one desires without fear of
the dreaded power arcs.

So what about efficiency degradation caused by the additional charging cycle
gap?  With the usual DC resonant charging topology, a five foot streamer
between twin 4 x 23 inch coils required about 960 DC watts.  The SPDT
topology required about 100 additional watts for the same five foot
streamer.  For me, it is a small price to pay to avoid RSG power arcing,
ammeter needles whacking past full scale, variac trying to jump out of its
core, etc.

Try it - you will like it.

Steve Y.

P.s.  I suppose one could call this topology a half-bridge.  Larry Robertson
posted to this list his results of a similar DC resonant charging topology
that is a full H-bridge.  It also is a good performer, but the RSG is more
complex since it must function as a DPDT switch.