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Re: [TCML] Idea... And some info on my first coil in progress!

Hi Andy,

A lot of people have tried new lists formats and the like (this comes up once or twice every year). I personally like it as is (you can read up on everyones thoughts on that topic also in the TCML archives).

Regarding your coil. None of the caps listed are suitable for the coil.

Cap1 is too large in capacitance (might make a nice can crusher).

Cap 2 I'm not sure about. The value is still too high for the NST. The voltage is pretty low.

Cap 3 might be good if you had the power to drive it and a larger coil. Aerovox only makes pulse capacitors with a voltage rating that high. However, the part number given I can't find at Aerovox. You may need to do some more investigation on the cap and see if you can hunt down the specs. You'll want to look at the pulse rate, rms current, etc. If it is a suitable cap for this type of pulse application, someone on the TCML might be interested if they have a coil large enough to use a cap value this high.

Using the NST is the smart choice for a first coil. But current is really low. The 0.25uF sizes are just too large (it would require 500ms to charge the cap and you really need a cap size that can charge in a time frame of about 20ms which would charge to 87% of the output voltage [or faster]). This means the cap needs to be .01uF which as you can see is vastly smaller.

With a 0.01uF, your coil would tune in at about 12 turns with something like a 6 x 20 inch toroid for a top terminal. For your coil, I would recommend picking up another 12/30 NST (preferably the same brand) and putting them in parallel to double up on the current. The coil is kind of large for the 12/30 but it will work. If you can pick up another 12/30, you can also double the cap to .02uF. Once again, an MMC is your best bet here.

Your primary spacing seems large, but it will work fine. It just doesn't need to be at 1". A coil this size would do fine even with 1/4" tubing with 1/4" spacing (edge to edge).

Take care,

Andrew Power wrote:
I'm new to the coiling thing and have enjoyed reading through some of the
old lists.  I joined the mailing list and find it very difficult as well as
inefficient.  I have forum software loaded on my web servers and I'm pretty
sure that the addition of a Tesla forum wouldn't use much bandwidth or
system resources.  Would this be something that the coil community would
like???  I just figured hey, it's free, why not give it a shot...   Anyway,
I have started building my first coil, and I'm not sure how I can make all
this work together.  Here is what I have so far:

4X - 1200 watt MOT
1X - 12kv 30ma NST

I don't know if these are suitable for Tesla use.  I just happened to come
across these for free.  I'm really hopping these can be used.

20,000 VDCW

.25 MFD

Type 20020
.25 MFD

The secondary is 22g wound on 6.375 outside diameter pvc.  I only had enough
wire to wind it 23 inches though.
The primary is .34 OD copper tube with 1" spacing.  Inside diameter is
7.375" and it has 7.5 turns.  Unfortunately, that's all the tubing I had
available at the time.

I don't really know if there is a way to get this to work without having to
get different caps or having to make another coil altogether.  This is my
first attempt and I admit, I rushed into it to quickly.  Anyhow, if any of
you have suggestions or know anything about those caps, please let me know.


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