RE: SSTC problems1 (no its not a PlasmaSonic ;-))

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

Original poster: "Aron Koscho" <kc5uto-at-wt-dot-net> 

Hi Jim,

   Sounds to me like your coil may be locking on to a harmonic rather than
the fundamental. How far is the antenna from the secondary? It should be
within a few inches of the base. Also, if the 555 is set to far from the
fundamental, the circuit may start with, and lock onto, the second harmonic.
I would recommend testing the bridge and gate drive with a separate
oscillator (TL494 50% duty or the like) and see if you can get the coil to
break out. If that works you know is a problem with the feedback circuit.

-Aron

KC5UTO
Aron Koscho
www.hvguy-dot-com



-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, January 26, 2004 5:48 PM
To: tesla-at-pupman-dot-com
Subject: SSTC problems1 (no its not a PlasmaSonic ;-))


Original poster: "Jim Mitchell" <electrontube-at-sbcglobal-dot-net>

Hi,
Today I finished my Feedback SSTC, It is based on Aaron and Justin's
feedback SSTC design, I am using a full bridge of FDH44N20 MOSFETS and a
18X 4.25" secondary wound with 30AWG.  After getting much help from Steve
Ward via email, I finnaly got to the first testing phase.  I tuned the
potentiometers right in the reigon that I saw the biggest swing on the
scope.  I had a neon bulb attatched to the breakout point, and at about 10v
input, the neon bulb striked.  I brought it up to 150v and the neon bulb
got very bright and I coul hear 60hz buzzing in the bridge.  Now I though,
well I'll reverse the primary turns.  So I reversed the primary turns, and
STILL the output was the SAME the neon bulb was lighting to the same level,
no increase and no breakout.  I am afriad my MOSFETs aren't being driven
into saturation by my gate driving circiutry.  Is there a way to test if
the MOSFETS are saturating?  Has anyone else experienced this and knows the
remedy?  Help!

Regards - Jim Mitchell