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Re: Puny transformer, will it work?
Original poster: "Karl L." <karl@xxxxxxxxxxxxxxxxx>
Hi Gary, Robert., all...
Your friends small NST will work for a small demo coil. I recently
completed a very small 'fun' coil using a bug zapper transformer
rated at kV at 8 mA.
Specs of my little coil:
Transformer: 2 kV at 8 mA. (measured carefully with multi-meter)
Capacitor: 1400 pF 20 kV doorknob capacitor from bug zapper. (does
get warm at these higher frequencies)
Secondary: 8 inches 30 AWG magnet wire on .9" fax paper plastic core.
Primary: 5 turns 12 AWG on 4" diameter plastic thin-wall tube,
raised 2" up secondary.
Spark gap: 1/8" tungsten rods in aluminum heat sinks/holders spaced
.04" apart.
Top load: 2.5" diameter foil covered sphere.
Operating freq. ~ 2 MHz
Photo: http://starcatfluffy.com/temp/tiny.jpg
This coil cost me nothing but time to build, and works surprisingly
well given the small capacitor and high H/D ratio of the secondary.
You can draw nice blue sparks from the sphere from 2" away, and it
will light fluorescent tubes from 2 feet away, and makes clear
incandescent bulbs look like plasma globes as well. The whole thing
draws only 18 watts, and if the cap dies from too much heating, I'll
make an inexpensive MMC. Of course, this tiny coil does not
generate the same kind of streamers to air as my larger coils, but it
was a nice little project regardless.
Best Regards,
Karl
On Apr 5, 2006, at 2:24 PM, Tesla list wrote:
Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>
Many, including myself, have gotten very satisfactory results from
4kV/20mA NST's. I've seen up to 14" sparks from mine, albeit with much
effort and NST de-shunting. I'm sure a 3/20 unit will be fine for a
science fair project. Just use a single cylinder gap, maybe .040" wide.
I wonder just how low a voltage is feasible?
Regards, Gary Lau
MA, USA
>Original poster: "Robert Hanford" <pomnept@xxxxxxxxxxx>
>
>Hello,
>Any input much appreciated.
>I am advising a friend on his daughter's science project. He got a 3kv
20ma
>NST for free and I wonder whether they are likely to be successful in
making
>a very small coil. I have never used such a small power supply.
>Many thanks,
>Robert Hanford