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Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
At 08:42 PM 9/3/2006, you wrote:
The first thing that everyone should know is that I am a junior in
highschool. I ran across the tesla a few years ago and have been
obsessed ever since. Unfortunatly 75% of all the money I make goes
into collage savings leaving me with not alot to buy parts and
such. I really appreciate that people like you are around and are
willing to help me. MANY THANKS
*The paper that i am refering to i downloaded somewhere online along
time ago but since is says information unlimited on teh top i am
assuming it origionaly came from here
I am also assuming that it is the
Easy to build table top tesla coil 250,000 volts one
Since it also says that on the papers
Cool! They have been selling those plans "forever". I am not
specifically familiar with this one but it gives me a good idea what
is up with it. if you search below for "btc3" some info comes up:
*The transformer I am using was bought off ebay for about 20$ It is a
6000v 30ma Neon Sign Transformer
someone I was talking to said that it might be centertapped or
something and that it could be the problem
Many (most) are center tapped but that should not matter. A nice LTR
cap size would be 21nF (20.8333..).
* dimensions of secondary + number of turns, winding length, and wire
10 inches tall
1 3/4 inches wide
#26 magnet wire
i have no idea what the length is
#26 wire winds about 58 turns per inch so that is 580 turns. The
inductance is probably near 2.4mH.
The coil probably tunes in the 980kHz range with the size top load
they show. This online JAVA program is very nice.
I bought the wire at radio shack and had to use 2 small spools to
complete it the wires were sanded and were put together but at some
point i thought that this was the problem and seperated them. then
moved my secondary up about half way. this made a huge
(the term huge means that i got an arc out of the magnet wire with
out the top load about 3/4 of a cm)
* dimensions of primary, number of turns, what sort of wire or
I was using #12 wire at 8 turns with 6 inch diameter
but when that did not work i took thick magnet wire and wraped it
around electrical tape on the secondary about 24 times. This seemed
to work better
(i got a small arc instead a a spark)
* number and type of capacitors and how connected - series? parallel?
That's a big problem!!! The capacitance is then 15nF / 20 =
750pF. You really want three strings with two of those caps in
series. Or 2 long by 3 wide. The capacitance is then 15nF x 3 / 2
= 22.5nF. Use about a three inch diameter primary and it should tune
very roughly guessing at 2.7 turns.
So right now your capacitance is 0.75nF and you want it to be about
22.5nF or 30 times more!!! that would completely explain way the
sparks so far are so small.
At some point i took some glass and 2 4in squares of tin foil and
tried that (it worked better but in practical terms not a big change at all)
* type of spark gap and how constructed
2 bolts mounted in lexan or something with a large computer cooling
fan sucking are through it the bolts are about .08 mm from each
other (which is as far apart as they will go while still allowing a jump)
That is fine.
At some point i made a small rotary gap to see it it would work
using a cd and small wires bend over it and then taped. Then i used
brushes to make direct contact with them. This seemed to work alot
better and was more consistant than the other gap so I have used it ever since.
Best to get the above working first.
* nature and dimensions of top terminal.
2 small pie tins welded together
about 4 inches in diameter 3 inches tall
*Some pictures of the parts and complete set-up wouldn't hurt either.
I dont have a digital camera or anything. But school starts soon so
i could ask to borrow one. If you could see it now you would say
wow what a piece of junk. I wanted to test it before i made it all
nice and such but it is the way it is so i never made it look nice
Not a problem. The primary cap value is the problem. this is a
small high frequency coil which is fine but your 20 caps in series
has a very low value. You need to use far fewer in series (two to
get to a comfortable 12000) and then put a few of those strings
together in parallel to get the value in the 20 - 25nF range..
If all is working, you will get a nice sparks then ;-)))
-------------- Original message --------------
From: "Tesla list" <tesla@xxxxxxxxxx>
> Original poster: Gomez Addams
> On Sep 2, 2006, at 8:23 PM, Tesla list wrote:
> >Original poster: jhowson4@xxxxxxxxxxx
> >Hello all,
> >I have a Problem for anyone who is willing to help me.
> >I have been trying get a coil to work decently for some time now
> >and have had little success. I admit that I know basically nothing
> >in terms of the math and formulas and all the stuff that you
> >already know.
> > I am following instructions to make a coil that runs off a 6000v
> >30ma transformer. I have 6000v 0.015mdf capacitors that the paper
> >says should work. But in the e nd of all my hard work and little
> >understanding i get a spark(not to be confused with an arc or
> >anything else that might look cool) out of the top terminal.
> >diffidently not what is supposed to happen. (according to the sheet
> >that is) What am I doing wrong? transformer issues? capacitor
> >issues? coil issues? what? Any help or ideas is greatly appreciated.
> We need a LOT more information than that to know what is going on
> with your coil. Such as:
> * dimensions of secondary + number of turns, winding length, and wire
> * dimensions of primary, number of turns, what sort of wire or
> conductor used
> * number and type of capacitors and how connected - series? parallel?
> * type of spark gap and how constructed
> * nature and dimensions of top terminal.
> Some pictures of the parts and co mplete set-up wouldn't hurt either.
> Is this an oil burner transformer or a neon sign transformer, or what?
> - Bill Lemieux