Original poster: Steve Ward
<mailto:steve.ward@xxxxxxxxx><steve.ward@xxxxxxxxx>
Hello Ken,
Good to hear from you again! I was just thinking today "i wonder how
Ken's SSTC is coming along?".
Just a few comments within. First of all, excellent work, it all
looks quite professional and looks like it can really push out some
big streamers :-).
> The bricks (courtesy of Steve Ward) are rather modest in capability & I
> hope, if all goes well, to be in the market for more robust ones e.g. the
> Powerex CM300DY-24H, for which I've provided space. Anyone offering
those,
> used but good?...
If you manage to break those siemens bricks, i do have some extra
CM300's that i am willing to part with (note, i have recently found
some CM400 half-bridges which could replace the CM300s in the event
that i manage to kill them... unlikely).
>
> To the left in TCH1 is the variac assembly. It, plus its cables for
> storage, will drop down inside a fiberboard box (behind, that was
> originally used to ship magnetrons). In that assembly I have a 20 A
variac
> (courtesy of Dave Leddon, and I thank him again for that!), a mains
> contactor, switches & circuit breakers, the 5 V/12 V power supply and a
> small board that holds the spark-burst controller. The latter includes a
> simple oscillator and pot for setting the spark rate. For setting the
> spark duration, I count primary cycles and cut off the drive after the
> selected quantity. Selection goes in 5 steps from 64 to 1024 cycles
You plan on driving the coil for up to 1024 RF cycles? That is just
way too many for the tank impedance you are running (read, extremely
high currents for a rather long duration). You should be running
anywhere from 5-20 RF cycles (i use about 8 cycles to get 10 feet of
spark on my large coil, that works out to 200uS). Hopefully you can
remedy this as i dont think you want to operate with such an extreme
number of cycles. Also, using so many cycles is highly inefficient as
far as power vs. spark length is concerned. Terry recently quoted
something like the best pulse length for a 2 meter spark is 111uS...
just to put things into perspective. In any case, you usually dont
want a pulse length greater than 250uS or so.
>
> If & when that happy day arrives when I actually make sparks, I'll add a
> triangular strike-screen above the electronics assembly: plexiglas to keep
> stray crud off the electronics and wire screen to keep stray
electricity off.
Im betting you will need it ;-).
>
> I've simulated a good part of my l.v. circuits, so perhaps that will save
> me just a bit of the frustration normally to be expected. I'm determined
> that this will be my last--my very last!--Tesla project; one has to stop
> some time and well-past-77 is more than a good age for that. Seventy
years
> as an electricity-nut...it's hard to believe!
Wow, kudos to you! I see myself building electronics after im
retired... but i shouldnt get ahead of myself, i still have 3 years of
college left!
Steve Ward
>
> Ken Herrick
>
>
>