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Re: first coil & help!!!
From: Raymond C. Howes[SMTP:rchowes-at-email.msn-dot-com]
Sent: Monday, November 03, 1997 9:55 PM
To: Tesla List
Subject: Re: first coil & help!!!
>
>From: Adam[SMTP:absmith-at-tiac-dot-net]
>Sent: Monday, November 03, 1997 1:08 AM
>To: Tesla List
>Subject: Re: first coil & help!!!
>
>Ray wrote:
>
>>I just built my first coil and fired it up and thought it was pretty
>>good,but.
>>Here's my spec's.
>>1st 1 15kv-at-30ma neon sign tran, 2 chokes one on each side of hv
lines.
>>Conected to 6 spark gaps. Using 8 16 oz bottles as caps. Primary 3/16
solid
>>wire at .25 spacing.
>>wound 8 times. Secondary 4.5 at 20 inches #27 wire. wound at 1300
>>times.Torid 4" dia x12"wide. First time I fired it I got a great spark
from
>>the center of the coil at least 12".
>>As I understand it should'nt come from the center of the coil. Through my
>>reading on Tesla info I figured it was overcoupled?
>
>Overcoupling, too much power input or improper tuning can all cause this
>breakout. In your case, I think it is the latter. You need more primary
>capacitance and inductance. Sounds to me like you are exciting the
>second harmonic of your secondary, meaning your tank circuit is tuned
>near an octave too high. Your big toroid and ground are anti-nodes, and
>the center of your secondary has the highest potential. Focus on
>lowering your tank resonant frequency by winding a larger primary, and
>building bigger and better caps. Your bottle caps are probably in the
>not up in the 0.01 microfarad range that you need for this coil. Do you
>have a capacitance meter, or any equipment with which to measure some of
>your circuit components?
>
>BTW, are your 16 oz. bottle caps glass? Don't use plastic coke bottles,
>these are made from Polyethylene Terphthalate, a polyester similar to
>Mylar. This is extremely polar and has horrible RF dissipation. I put
>aluminum foil on either side of a 2 liter pepsi bottle once, and hooked
>it to a bank of neons and it melted in a few seconds.
>
>>I had a spare transfomer and added it to all the mess. Now I'm at
15kv-at-60ma.
>>Seconday still the same. Little spark and still from the center of the
>>coil.
>
>Adding transformers is going to make things worse, since the more
>transformers you add, the more primary circuit capacitance you will need
>to achieve the correct capacitor charging rate.
>
>>Again it would only fire with the secondary ground disconnected. I'm
>>ready to start all over again with a new secondary.
>
>God no! Don't undo all that work! Work on tuning the primary to match
>your secondary. If you don't have a signal generator & o-scope handy,
>you will need to experiment a lot more to get yourself in the right
>ballpark. Using tesla coil design equations can also help you get to the
>right place faster (see www.pupman-dot-com, and search the archives!)
>
>I hope this gives you some new hope. It will work soon enough...
>
>-Adam
>
>
>
>
>--------------------------------------------------------------------------
>Adam Smith
>absmith-at-tiac-dot-net
>Epoch, Inc. Digital Music Project
>
>www.tiac-dot-net/users/absmith/ Now with MP3! Musik. Macht. Macintosh.
>--------------------------------------------------------------------------
>I'm really just a beginner, I have no electrical measuring devices but volt
&ohm meter.
I have to do things by trial and error(saftely). I widened the gap on the
primary from .25 to .50 between turns and it did help.
my caps are now 8 glass 16oz bottles satl watermix.
I found some new bottles at winn dixie. 32oz nice shape. should I try six of
these or just add more 16oz bottles?
If I get enough nerve I may try to roll my own caps. The only problem I see
with that is using the vacum pump to draw out the air.
Any other Ideas?
One more question. Why doesn't the spark gap fire when the secondary is
grounded?
>
>