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A few questions
Quoting Kyle Chadwick <kylechad-at-airmail-dot-net>:
> I am in the middle of making my first Tesla coil and I have a
> couple of questions. Please answer as many as you can.
First off, congratulations for trying and good luck in your
efforts. We all had to start with number 1.
> 1. The plans I have say to take some insulation off the primary
> for the tap. What is a tap?
We would like to hear more about your plans. As many specifics
as possible, without taking too much time from your construction
efforts, may help us to identify weak areas that can be corrected
during the construction. Now on to your question: what is a tap.
The tap is a movable connection used to tune the tank circuit of
the coil. The Tesla tank circuit is the simplest LC RF oscillator
that I am aware of. It converts line current into pulsed RF.
The three major components of this circuit are: primary coil "L",
high-voltage capacitor "C", and the spark gap switch. The "L" for
inductance (or primary coil) and "C" for the tank circuit capa-
citance also helped to derive the name "LC oscillator" for this
circuit.
The frequency of oscillation in this circuit is determined by
the size of "L" and "C". Once of the easiest way to tune, or vary
the frequency, is by changing the value of "L". In this circuit
it is perhaps best if the primary coil "L" has no insulation at
all. The electrical length of this coil in the circuit can then
be varied by using a sliding or clip terminal to connect to the
primary coil at different points. This movable connection is
referred to as the tap.
> 2. I need to adjust the spark gap until I get the largest arc,
> right?
You will need to adjust a number of factors ("all") in order to
get the best spark. The gap is one of these adjustments.
> 3. For the terminal I going to use a Styrofoam ball wrapped in
> metal duct tape, will that work?
Yes, but you would be better off with a foil covered or metal
donut called a toroid for use as a discharge terminal. These can
be simply made by forming a circle of dryer ducting, Volkswagon
heater venting, even plastic drain pipe covered with aluminum
tape. The center support plate can be made of metal, or foil
covered plastic or masonite.
> 4. for the insulation on the secondary I am going to use three
> cans of spray on acrylic spray, does it need more?
That should be fine to get you started. You can always add coats
later if required.
> 5. the plans call for a 6000v transformer and a .005 uf cap, do
> you think that a 15kv neon light transformer and 12 wine cooler
> salt water caps would work?
Yes, but 15kv can be a little hard on one's first effort. I would
get a couple of neons. Start with a 9kv neon, then move up to a
12kv neon.
> 6. It calls for a choke, but I thought because i have a neon
> light transformer that I don't need it. Is that right?
You need something, but figure your coil is going to eat a
transformer or two in it's lifetime regardless. Your choke should
have a metallic core, like a hefty iron powder or ferrite ring
with a few dozen or more turns of thin wire on it.
> 7. I Am doing this for science fair, can you think of any
> problems or questions that a Tesla coil will solve?
Tesla coils are more of an educational tool than a problem
solver. It can be used to teach loads about such subjects as:
transmission line theory and VSWRs (Voltage Standing Wave Ratio),
resonators, peak power amplification, skin effect, air core
transformation, the list goes on...
Richard Quick
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12