[Prev][Next][Index][Thread]
Re: Help PLEASE! So close.. and yet...
In a message dated 4/23/99 4:28:32 AM Mountain Daylight Time,
tesla-at-pupman-dot-com writes:
> The power supply is
> 7500 volts at 30 milliamps(that's 220 watts). The capacitor is a
> leydan jar of an unknown capacitance. The primary is about five turns
> of really big fat copper stuff. As I said, that all works fine. The
> secondary is 30 AWG enamled magnet wire (the really thin red stuff -
> it was all I had) wound about 3/4 the height of a thin untreated
> cardbord wrapping paper tube (2 inches diameter). A softball wrapped
> nice and smoothly in aluminum serves as the discharge terminal. What
> is wrong? Is the cardboard conducting all the RF? Is the wire fatally
> thin? Help, please!
>
> -Yuri Markov, would-be coiler
>
Yuri,
The first hint is that your capacitance is unknown. How can you tune
your coil without knowing this? You need at least .0106 uF for that
transformer. More would be better, from what I have been reading
lately(like twice that even). How many bottles do you use? I am only
guessing, but you probably need something like 14 or 15 in parallel(I am
assuming 750pF per bottle).
Second, that wire is a bit thin, but should produce something once you
are tuned. I wouldn't worry too much about the lack of varnish on the
cardboard, since you've already wound it. If it frys, it frys and you start a
new one. You didn't mention how long the secondary winding is, so I cannot
say for sure, but you may need more primary turns to get it tuned, even with
.01uF primary cap. If you give some details, I,or others, can estimate the
number needed. I am imagining a long skinny secondary, so the classical
equation for inductance may actually work better than the Wheeler equation
for your secondary. In either case, you will have to tune the primary coil by
"trial and error" tapping until you get some spark output and then optimize
it.
Mike