Re: its alive.....or not

[Terry Fritz <twftesla-at-uswest-dot-net>]

Hi Mike,

At 08:32 PM 9/10/00 -0500, you wrote: 
>hi all,
> 
>i have finished my first tesla coil YAY. 

Neat!

>Its powered by a 9kv 60ma neon. 

Resonant cap size = 17.68nF (talking to myself here ;-))

>i 
>am using a MMC with 3 strings of 12. they are the caps from the latest bulk 
>buy (2000v .068mfd). 

17nF so you are running right at the resonant size.

>i am using a 3" diameter arylic tube wound 18 inches on 
>the form. it is wound with 22 ga magnet wire. 

652 turns 4.94mH

>i am also using a pancake 
>primary with 8 turns. with 1/4" copper tubing. now for turning it >on.....
> 
>ok i started by setting my gaps the safety so that they just dont fire. 

Excellent!!  Your running right on the resonant point of the
transformer/cap.  If your turn it on without a gap, the voltage will shoot
up to maybe 80,000 volts!!  The safety gap will insure you don't blow the
transformer up if the main gap is set too wide or does not fire.

>i 
>set the primary gap to fire at 111 volts input. then when i stood away and 
>had the gaps hooked up it started to fire at 28 volts. 

Since you are running resonant, this is normal.  With only 28 volts in you
were still getting about 13,000 volts out!!  The firing rate should have
been very low and sporadic.  As you turn up the variac, the firing rate
will increase to about 145 BPS.

>so i decied that i 
>just will set it wider and tryed it again. 

Eeeeeak!!  They "were" set fine.  If you increase the gap spacing, the
voltage will go higher than the NST can take!

>this time it started firing at 
>about 70 volts but... when it hit about 90 volts it started to arc in one of 
>the strings to itself. 

Sounds like the voltage is running super high!!!  Your NST must be a good
one to take that voltage.  Put the gaps back to where you had them.  The
NST will not live long at higher than designed voltage.

>there is abour 1/2in space between where the sting 
>breaks in two. the caps are like a loop of 6 on each side. so it started to 
>arc between those then i dicided that i am going inside. 

The MMC acted as sort of it's own safety gap :-))  Probably no harm done.
The caps can take a lot of abuse and the 9kV tranny obviously has a lot of
head room as most 9kVs do.  You picked a great time to quit and go think!

>the bugs were 
>killing me there we thousands. so what i have figured out is that i need to 
>eather space those out which would mean just cutting the boards in two and 
>connecing them together with on wire or i might jsut though some little 
>strips of acrylic between the rows. does anyone know the best way to do this? 

Put the gaps back to where they were.  Then tune up the primary tap point
until you start to get streamers.  Use a nail point if you need to get the
streamers started.  That makes tuning much easier.  You only need to turn
the variac up until the gap fires to tun the coil.

Once it is all tuned and you are feeling good about it, you can crank up
the variac and start frying bugs ;-))

> 
> 
>also remember dont set your acrylic tube on the cement by you feet. i am 
>really mad because i took a real good chip out of the tube but thankfuly it 
>didnt effect the windings.....

Glue...  But try gluing a scrap piece first since some glues really attack
acrylic.  Some people wrap their secondaries with a protective layer of
plastic or such to make it accident proof.  Usually does not look as good
as the bare coil though.

Glad your coil is going well and you didn't start coiling by blowing your
NST like we all did ;-))  It should work great!

Cheers,

	Terry


> 
>thanks alot,
> 
>MIKE
>