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

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

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

Hi Jan, et al.

Well I brought the antenna closer, and I touched my variac with one hand,
and the antenna with the other,  heard that 60hz hum again, and I let go.
When I let go, I saw a squiggle show up on the scope, and the neon bulb on
top of the breakout point was lighting.  I raised the voltage to 150, and
touched the neon bulb with a screwdrive, it got brigher then went out.  I
tapped on the antenna again whilst touching my variac, and the oscillations
started again.  I tried reversing the primary, same thing.  What in the
world is causing this?  It seems to be running off its own feedback but
power is like 000000 it is probably putting out 200v max on the breakout
point, and yes the secondary is grounded.

Regards - Jim Mitchell
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, January 27, 2004 9:54 AM
Subject: Re: SSTC problems1 (no its not a PlasmaSonic ;-))


 > Original poster: Jan Wagner <jwagner-at-cc.hut.fi>
 >
 >
 > On Mon, 26 Jan 2004, Tesla list wrote:
 >  > Original poster: "Jim Mitchell" <electrontube-at-sbcglobal-dot-net>
 >  >
 >  > I have ruled the problem out to be in the section that receives
feedback
 >  > from the coil.  The reason the coil is running crappy is because the
555
 >  > timer is running it, instead of the feedback.  It seems the feedback
doesn't
 >  > have enough "oomph" to kcik in and take over the 555.  So I removed the
555
 >  > and banged on the antenna with a screwdriver.  Neon bulb on the
breakout
 >  > point flickered and I hear a 60hz hum in the GDT section, and thats it.
I
 >  > will try more filtering on the input and see if I can get it to run
with out
 >  > the 555.
 >
 > If you've a filter after the feedback antenna, don't! Filters just
 > attenuate or screw up the phase. (on the mains voltage side, a larger
 > smoothing cap is of course fine, but streamers will start looking
 > different)
 >
 > Placement of the antenna is often surprisingly critical. You can try using
 > different lengths of wire (~20..40cm) and lying it out in different ways
 > e.g. on the desk/floor: towards coil, counterclockwise along coil,
 > clockwise, ... Or sticking up vertically, etc.
 >
 > good luck,
 >   - Jan
 >
 > --
 > ****************************************************
 >   Helsinki University of Technology
 >   Dept. of Electrical and Communications Engineering
 >   http://www.hut.fi/~jwagner/ - jwagner-at-cc.hut.fi
 >
 >