Review of BTC-3 Tesla Coil Kit From Information Unlimited
April 23, 1992
Falls Church, VA
Like many of you I am sure, I have read several autobiographies
over the years and have become fascinated with both the man and
inventions. I had for some time desired to actually BUILD a Tesla
Unfortunately, I suffer from a very poor education when it comes
electronics. The thought of building a device with such high
output was very intimidating to say the least! To my rescue came
Summer 1992 catalog from Information Unlimited. Add to this that
quit my job (i.e. I had some time on my hands) and that $240
to be an unreasonable amount of money to spend for a time killer
not searching for a new job) and dream fulfillment.
It occurred to me that there may be other Tesla novices out
might be interested in trying to "feel the power" of
a real Tesla coil
fashioned with their own hands. This brief write-up will let
Tesla coil builder, whom chooses to start their Tesla building
a BTC-3 kit from Information Unlimited, to have a better idea
of what to
expect if using the BTC-3 kit.
The BTC-3 kit, when finally put together, delivered the 12"
promised from the 250 KV output. However, a few screws necessary
the construction of the coil were missing from the kit and necessitated
trip to the local hardware store. The directions were cryptic
drawings didn't match the eventual configuration as built. Some
appear to have been substituted for those that were described
directions requiring some improvisation in order to get things
The kit required very little in the way of tools, or knowledge
electronics, to put together and required a total of about 10
two weekends to construct. In spite of some of the changes required
during construction, I found the kit satisfactory and worth the
I also went on to buy the optional Toroid Terminal after completing
coil and I would highly recommend it to anyone considering building
BTC-3 kit. While the bare wire coming off the top of the coil
considerable sparks, it was only when I attached the Toroid to
secondary coil that the coil seemed to "come alive"
and produce an
incredible discharge field and a constant output of 10"
to 14" sparks.
Well worth the extra $69.
Now, I am ready to move on to building a 1 million volt coil
that I hope
to build from scratch! (with plans yet to be determined....)
An initial quick inventory of the parts in the kit as compared
parts list included with the kit showed that several screws were
These are the kinds of missing parts that are very frustrating.
figured the long distance phone call requesting Information Unlimited
send me the screws would be more expensive than just going out
buying the screws. Other than that, everything appeared to have
included. I feel that potential purchasers of the kit should
aware of the following:
- The secondary coil included in the kit was wound sloppily
about two hours of my time to get it wound tight and without
overlapping wires. I began wondering if I couldn't have wound
from scratch in the same amount of time and saved the money of
to buy a pre-wound coil.
- There were no screws included with the kit that could be
attach the top (the part that the secondary and primary coils
rest on) to
the tank enclosure containing the transformer, capacitor, etc.
- There were no screws included that could be used to attach
transformer to the bottom of the tank enclosure.
- The ON/OFF toggle switch included with kit did not match
in the plans and because of a protruding tab could not be attached
the side of the tank enclosure. I was forced to cut off and file
PLANS & DIAGRAMS:
The plans include a nice brief introduction on Tesla coils
- what they
are and are supposed to do. The plans also include a nice conclusion
that describe options that the builder can add to the coil (that
produce additional effects and features for the builder).
The drawings and diagrams in the plans appear to be taken
different sources, or at least drawn at different times by different
people. The formats of the drawings change frequently; in a couple
places two drawings of the same assembly on separate pages didn't
match. The drawings at times do not reflect the associated instructions.
This led to occasional head scratching moments of pondering on
resolve the problem, "Do I go by the instructions or do
I go by the
drawings?!" Generally speaking, the drawings were accurate
and I used
them frequently to make sure I was on the right track.
The instructions were actually pretty good. Descriptions were
followed a logical stepwise path through the construction of
Thoughtful comments are sprinkled throughout the instructions
pitfalls to avoid and/or variations that are possible as the
kit is put
together. One gets the feeling that someone had written the instructions
and then had actually gone through them and tested them for accuracy.
The only exception to my praise of the instructions, though,
is that the
instructions had not been modified to reflect obvious last minute
changes that were shipped with the kit. There were also a couple
instances where the instructions were verbally correct, but the
referenced by the instructions appeared inaccurate and did not
the associated instructions. I'm not sure that this is a fault
instructions or of the drawings?!
- An interesting conclusion drawn after the construction of
the coil was
complete, was that the kit required no soldering at all. For
mind (and for habits sake) I still soldered all the obvious connections,
but in fact didn't really need too.
- A finer treaded screw should be used for the spark gap adjuster.
takes quite a bit of fiddling to get the gap to the width that
for continuous operation at maximum output.
- Generally speaking, the initial output of the coil was much
advertised; perhaps 8" sparks at best. I added a second
(identical to the one included with the kit) and wired it in
the first and then got the spark output I desired. While it is
that I didn't get the coil tuned properly initially, or that
assembled something properly, the addition of the second capacitor
the trick for output.
- The secondary coil comes with a plastic cap covering the
top of the
PVC tube used for the coil. This appears to be unnecessary and
end I had to remove it so that I could patch some arcing that
occurring inside the tube.
- The plexiglass plate used in conjunction with the spark
should have had an adhesive included in the kit for attaching
to the side
of the enclosure. I had to run out and buy some epoxy glue. It
have been a nice touch to have had this included.
- The power cord is supposed to be securely attached to the
enclosure by using a plastic grommet. Unfortunately, the hole
power cord grommet was much too small for enclosed grommet.
- The neon bulb holder was too large to securely hold the
necessitated the elimination of the use of the bulb as part of
finished kit. This didn't effect the ability of the coil to run,
probably would have added some "polish" to the look
of the coil when
completed and operational.
- It is an absolute necessity to corona dope all exposed wire
in the tank enclosure. Failing to do so leads to arcing inside
- I recommend that the secondary coil be insulated with a
paraffin wax as opposed to corona dope. The coil arcs through
coating of dope as if it weren't even there. However, all arcing
eliminated with a single thin coat of paraffin wax. Its a heck
of a lot
cheaper than dope as well!
A great deal of "thanks" goes to my good friend
Dr. Rin Saunders whom
without I never would have known about Tesla and whom acted as
patient guide and friend during the construction of the coil.
It was he,
back in 1986, that first enlightened me about Tesla. He had also
built a Tesla coil some 25 years ago as a young teenager and
therefore able to provide valuable guidance when the instructions
diagrams (or parts) didn't quite match. I have included his commentary
on the kit and its construction above.