Re: New spark record

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

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

In a message dated 12/27/00 8:19:16 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

> > Jason,
>  >
>  > That's an excellent result using just two MOT's.  I used 4 of them
>  > in series and only got 63" sparks, at 4kVA.
>  >
>  > To have the coil running on a 15amp 120 volt line along with the
>  > compressor too, and get 6.5 foot sparks, is truly amazing,
>  
>  Well 6.5  foot if you count all the curves and turns of the sparks. 63" is
>  about all mine were point to point, and the air compressor doesn't draw 
that
>  much, probably around 2 amps max (it's little), not to mention that when I
>  run at full power it only takes a little over one minute to trip the 
breaker
>  (the gap power arcs and starts drawing alot of power).

Jason,

Well 63" is still a good result.  Some of the breakers can withstand
a little more than their rating I think.

>  > My similarly sized secondary develops racing
>  > sparks when I reach 63" sparks or so at 120 bps.  This suggests to
>  > me that your coil is firing at a higher break rate,
>  
>  Your right about the higher breakrate. The spark gap is firing very fast 
and
>  gets to a very high pitch scream when it heats up, I also have the racing
>  sparks however when I turn up the power, but only when I don't have a
>  breakout bump. What size capacitor are you using at 120 bps? I'm using all
>  of 110 nf and I would guestimate 300+ bps from the pitch of the gap.

I'm using a 14.7nF cap at 120 bps.  But my voltage is higher on the
TT-42 coil since I'm using a 12kV NST.  The MOT coil used a higher
bps, and a larger secondary (?), or I may have been running it as a
magnifier, I forget, but it's written in my notes.  My MOT coil probably
used 0.075uF at 600 bps.  A low voltage coil needs a much bigger
cap value in general.  If the voltage is halved, the uF must be four
times larger, for the same bang size.

>  > Are you using a voltage doubler with the MOT's?  Do you have
>  > a website that shows the coil?
>  
>  No and No. I'm running the MOTs without any modifications or additions
>  (besides being in an oil bath). I just apply the raw 4800 volts to the tank
>  circuit. As for the website I'm working on one that seems to be a big pain
>  in the butt, I keep having problems uploading it and putting it together 
for
>  that matter. I may be able to get up a simple page dedicated to the MOT 
coil
>  in a few days. I'll have to get some pictures first (i've taken two rolls 
of
>  film with a cheap disposable camera and another crappy camera and none of
>  them turned out. Maybe Santa will get me a nice digital camera :-)

For spark photos, I think a normal camera is best, but you need a long
exposure such as 10 to 20 seconds or so to see the sparks best.  The 
camera needs a "B" speed setting where you can leave the shutter
open for awhile.  Some of the websites are probably a little easier to
set up than others.  

I finally finished my new "four series rotary" sync gap (120 bps), I just
have to add an ac line cord.  I'll post a picture at my website when
I get around to it.

John Freau

  
>  MOTs rule
>  Jason Johnson
>  
>  >
>  > John Freau