Re: VTTC/SSTC Spark Appearance Comparison

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 4/1/03 10:31:04 AM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:


>So my question is, why are VTTC arcs perfectly straight, and SSTC
>arcs not? Don't they work the same way? They both (VTTC and SSTC)
>switch CW power into the primary right? I know exactly how SSTC's
>work, but I've never looked into VTTC's, so can someone please inform
>me exactly...exactly...what the primary sees in a toob coil? If you
>can describe, or link to a waveform, it'd be great.


Justin,

Not all VTTC's produce straight sparks.  Many of them produce the
same sort of branched sparks as SSTC's produce.  There are many
factors that affect the spark appearance.  Some of the factors are;
tuning, power supply, component spacing, feedback adjustments,
RF envelope shape, pulse rate, secondary design (maybe), etc.

For example, my 24" spark dual 833A coil gave branched sparks
until I replaced the plate transformer with an MOT.  Then the sparks
became very swordlike.  When I re-configured the coil into a portable
design, the sparks became branched again.  The same thing happened
on my 15" spark staccato TC.  My 36" spark TC always gave branched
sparks no matter what I did.

I did a series of tests in which I varied the RF envelope.  Envelopes
which rose gradually gave straighter, longer sparks than envelopes
which began at a high level, and stayed steady or declined.

the primary waveform in a VTTC is an RF sine wave forming an
envelope which rises and falls with the 60Hz input power.

My VTTC's can be seen at my website at:

   <http://hometown.aol-dot-com/futuret/page3.html>http://hometown.aol-dot-com/futuret/page3.html

click on the links as needed.

John