[Prev][Next][Index][Thread]
Re: Need Help.
Don't touch your coil, but if you can get some high voltage rectifier
tubes you could very easily build a bridge rectifier that you could rely on,
and then you could use V/I from the output of the neon transformer to find
the output impeadance after the retifier, or at present for the AC value.
Then you would need to find the average voltage, and current output using
2(Vpeak)/pi = Vave, defined as the average voltage, then you work the
equation for impedance. It's not a true AC output to the Tesla coil using
the rectifier, but when you replace R in the equation F = R(C)(2)(pi) you
can equate the frequency of the spark gaps output by multiplying that value
of Capacitance by five. Reversing the equation gives you the value of
capacitance that you'll need. So, since you have R which is equal to the
impedance of the output of the neon transformer, the Frequency=F, and the
constant pi, you can reverse the order of the equation. Therefore, C = ((F
the desired frequency)/2(pi)R).
In typical circuits a capacitor only charges to 1/5th of the maximum
voltage. So, the time that a capactitor would require to discharge an arc
is 5 times longer, so when finding the value of Capacitance you would need
for this circuit using the equation above you would need to then Divide it's
calculated value by 5 to be discharging through the spark at your peak
voltage. You would need to work all of the equations to check if your not
using something else that's automated. You would need something for
calculating a spark gap using capacitors specifically, not just the coil's
resonant frequency..
James.
.
>Original Poster: "Gregory R. Hunter" <ghunter-at-enterprise-dot-net>
>
>Dear Unknown Coiler,
>
>Is your spark gap firing at all? If it is, you should get a little bit of
>spark even if your coil is way out of tune. Put a top terminal (toroid,
>coffee can, metal salad bowl, etc.) on the thing and tape a pin or
>thumbtack on it with the point sticking up. Darken the room. Try each
>primary turn, one by one, until you see some corona on the pin point, then
>fine tune for longest spark. If you never get any corona, change your
>capacitance value & repeat the process.
>
>I ran your secondary numbers in WinTes and it predicted about 350kHz if you
>use a top terminal, and over 600kHz if you don't. Your cap seems too
>small. WinTes says you can use up to .016uF with your 10kV NST. My own
>measurements indicate 750ml wine bottle caps are only good for about
>.0013uF each. You'd need a dozen of them to achieve .016uf. Also, your
>gallon jug probably doesn't have as much capacitance as you might think.
>Glass surface area--not container volume--determines capacitance. Since
>the volume of a round bottle grows much faster than surface area as size
>goes up, you're better off with many small bottles rather than a few big
>ones. I suggest standard 12oz beer bottles arranged in six-packs. A
>carefully built six-pack is good for about .005uf, so three six-packs will
>give you a nice, compact cap for your NST.
>
>My two pence worth.
>
>Best of Luck,
>
>Greg
>
>----------
>From: Tesla List[SMTP:tesla-at-pupman-dot-com]
>Sent: Wednesday, November 18, 1998 8:06 PM
>To: tesla-at-pupman-dot-com
>Subject: Need Help.
>
>Original Poster: kc1-at-ime-dot-net
>
> I need some help getting my first coil up and running. I'm using a 10000v
>60ma neon sign transformer. My primary is 1/4" copper tubing, in a normal
>helix, about 10 turns spaced approx. 1/4" apart. The secondary is 3"PVC
>with 21" of 24GA wrapped around it. I'm using two wine bottles and one 1
>gallon jug for caps. The spark gap is constructed of two 'L' brackets and
>bolts.
> I turned on the power, nothing happened, there is juice going through it,
>I touched a flourescent bulb to the primary and it lit. How close to in
>tune does a coil need to be before you can get arcs and sparks out of it?
>Can anyone help me? suggestions for a discharge terminal? thanks!
> I went by diagrams and info found here...
>http://www.altair-dot-org/tesla.htm#newcoil
>
>
>
>
>
>