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why small is better
i would just like to share my story with the list of how my knowledge
of teslacoils came to be, from my very poor beginings to finally
undrestanding most of the theory and workings of a teslacoil. i think this
may be helpful to some beginers thinking of building their first teslacoil.
First of all the main problem with me is that i started WAY to large,
the first teslacoil i ever made had a 6" secondary by 2' long wound with
24gua copper wire, the reason i made it so large is because i thought this
would give me larger sparks even if my powersupply was very small. also one
reason it was so large is that my dad owns a lathe so it only took me about
30min to wind the whole thing.
the primary went through manny stages of development, it started off
as a slapped together bunch of poorly aranged 1/4 refrigerator tubing with
17 turns maximum. eventually i took the time to build a nice former out of a
cutting board with holes drilled in it. if you are a beginner i would highly
recommend starting with a primary coil made with wire ties, mainly because
wire ties allow you to have a solid connection for each primary turn as you
put in on the former. for me i had to bend the copper pipe to exactly the
shape it needed to be, this is very hard as any change made to a turn
affects all the other turns.
my spark gap was 8 1/2" copper tubes 4" long aranged on a cutting
board with holes drilled in one side and then tapped to accept machine
screws. this design worked fairly well as it was easy to change the gap
spacing because you dont have to fool around on the inside of a pvc pipe
like the RQ design gaps, but the down side is that it had to forced air
cooling or quenching (with my powerlevels it never even got warm).
my prized NST (neon sign transformer) was a 12kv 30ma magnetec one
that i got for 42$$ used at a local neon sign shop (i live in hawaii and
dont have manny choices of where to buy things).
for a toroid i used 4" plastic ducting from a dust collection system
and covered it with aluminum tape it is 12" diameter
capacitor (almost forgot this important element) i used 6 beer
bottles in parallel for estimated uf of .0066 which is optimum for the 12kv
30ma NST, also tied a flat poly plate cap with alum foil electrodes (i
killed it by opening the spark gap up to farr). lastly i bought 50 .1uf
3000volt poly capacitors to make a mmc with, i aranged them in a string of
15 for .0066uf 45kv (very overrated). ALL these capacitors performed very
similar proving that salt water bottle capacitors are a very good choice for
the beginner.
Results: the spark length from this coil was very dissapointing, the
max length was about 7" im still not really sure why it worked so poorly,
maby it was just me not knowing how to tune it properly because the primary
was 17 turns and i didnt really know anything about resonance. also tied was
a 6" coil 2' long wound with 28 gua, a 4" coil 2'long wound with 24gua all
with similar results.
just recently i have also redone this entire setup with new RQ gap, new
capacitor and some other improvements, since i now understand tuning i have
been able to get 20" sparks.
NEW COIL
after being theroughly (bad spelling) dissapointed with that coil i
didnt do anything with tesla coils for about a year and a half.
then just 2 weeks ago i was surfing the web and came across a few tesla coil
web pages. this sparked my memory and i wanted to again try and build a
working teslacoil. but this time i wanted one that worked !! it seemed to me
that a very small table top coil would be real nice to have and play around
with as i could keep it in my room also.
this eventually led me (after actually calculating the dimensions,
unlike the first time) to build a very small 1 1/4" wide 12" long secondary
wound with 28 gua on a PVC former.
primary is 16gua solid aluminum electric fence wire (i had a roll of
it laying around) 15 turns on a 10" diameter plexie glass circle with a line
of holes drilled in it every 45 degree. the holes are spaced 1/4" i then
used small wire ties to secure the aluminum wire to the plexie disk. this
was the easyiest primary i have ever made and looks GREAT all the turns are
in perfect alignment.
power supply: small 7kv 20ma NST (voltage is a estimate because it
doesnt have a label, but i did measure current with a multimeter)
spark gap: single pipe gap (1" copper pipe 3" long)
capacitor: .0044-.01uf mmc (variable by changing how manny capacitors
are used )
topload: 3" stainless steel sphere
results:
with the 3" sphere max spark length is about 6" and coil
tuned at about 4 turns on the primary.
i have also tried using a pamelo( large 6" diameter fruit,
looks like a gigantic orange) as a top load, just to see how long a spark i
could get with a bigger topload. and sure enough i was able to get 9" sparks
to a grounded rod from a screw pushed into the fruit (breakout from pamelo
was very small without a breakout point). coil tuned at about 7 turns with
this larger topload.
overall i am very pleased with these results and will continue to
experiment with this mini coil design to hopefully improve performance even
more.
please excuse all the spelling mistakes and such if any of the info
contained in this is wrong please let me know i am very sorry if that is the
case.
chester lowrey
P.S. there are some old pictures of my LARGE coil setup on my web page, but
i havent had the time to photograph the new mini coil yet. as soon as i do i
will put them up on my page.
http://www.geocities-dot-com/hilo90mhz/
some thanks are also in order from the two web pages that gave me ideas on
this new and improved coil:
http://www.angelfire-dot-com/ga3/tesla/ Greg for his primary made out of wire
ties
http://www.powerlabs-dot-org/ Sam Barros for the idea of a small compact
efficient teslacoil
Chester Lowrey (AKA MŽ. Penguin)
---------------------------------
"if all else fails, BLOW IT UP!!"
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