Re: Capacitor Help (spark gap)

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Original poster: "MalcolmTesla" <tesla@xxxxxxxxxxxxx>

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, December 20, 2005 5:54 PM


> Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>
>
> Hello Malcom
>
>  > That looks interesting.  I take it the spark gap is very important with
>  > regards to output.
> indeed it is, but at your current power levels its may prove pretty easy
> to build a good solution for a static gap, your approach sounds
reasonable.
> I am not sure how thick a penny is, sounds like it could be a bit too
wide,
> but then again, you can use less gaps and will be OK.
> However, the idea is not to strain the gap, but to distribute it into many
> smaller gaps wich can transport heat away better, thus helping quenching.

I did make the 4" PVC spark gap with copper tubes in there.  I saw a pretty
big improvement over just using the two bolts so I was very pleased with
that.  It makes sense that if I go to a gap even smaller than a penny and
distribute the spark over even more tiny gaps it would work even better.  I
think I'll build another 4" PVC spark gap with credit card width gaps this
time.

>  > Interesting you should mention that.  It came to mind and we didn't
have
>  > anything handy right here at work to put inside the secondary so we
stuffed
>  > some wal-mart bags in there to form a dielectric between the top and
bottom.
> Hm, I am not sure if this would help. Additionally, if you fill your
> secondary with
> a bunch of material, this should not aid the HF-propperties. If have no
idea
> how many bags "some" are ;-)

It was actually only two bags.  One on each end all crunched up.  I will do
something more professional soon.

> At lower power you should get away without any baffles, just make sure
> the inside of the tube is clean, dry, no oil, you can still sand, dry
> ( not bake )
> and warnish the inside of the tube if you haven't done so, yet.

I agree.  That's quite a jump down the tube but once I get more turns on my
primary and get the system in tune properly it may be important.

>  > I got to thinking... what about a rotary powered spark gap?
> Nice to have, I prefer the SRSG, but more for smooth operation,
> not neccessarily for performance reasons. However, A-RSG may
> sound cooler, but are amlost sure deadly for your NST, unless you use
> high break rates...
>
>  > old spark plug distributor from a car and attach an electric motor to
it?
> I doubt it will work too well, after all it was not designed to handle the
> power(currents). There is usually a small carbon rod that makes contact
> with the center of the rotor, this is so not pulse-power-compatible.. ;-)
>
>
>  > With a rotary spark gap do you just set the motor to a certain speed?
> With a RSG, yes, you chose the speed in a manner, that the number of
> revolutions and the number of electrode-alignments gives you the desired
> break rate, typicaly 100, 200, 300, 400 bps, other configurations are
> possible, but the positive effect of an SRSG vanishes somewhat over 300
> or 400BPS.
> With async RSG's you can vary the speed and by this the breakerate over
> a broad range, but there usually is a sweet spot. Usually you use ARSG
> with higher bps to avoid problems with surging. To really go from zero to
> "whatever it might withstand" you usually need a special supply....
> another story...
>
>  > busy charging and the distributor lines up the terminals and discharges
it?
> as long as the gap is able to fire, the is at least nothing dangerous
> about that,
> unless you go below 100bps. But this is usually this is not the best mode
of
> operation for an rsg. One advantage of an RSG can be, that you can
> predetermine when exactly the gap should fire, thus being able to charge
> a bigger cap ( more energy ). Optimum cap sizes for each gap type will
vary.
>
>  > I don't know, maybe I'm just thinking to hard about it :)
> No, the idea came to my mind when I started coiling, too. But I never
> tried it. I felt it was too obvious it would not work too well.
> I find myself thinking if one could modify such a thing.... surely
possible
> but no, that just too wierd...
> C'mon anyone, proove me wrong! ;-)
>
> You did a great job with your coil in such a short time, congratulations!
>
> best regards
>
> Christoph Bohr

Lots of good info there.  Thanks.

Malcolm - KC