Re: DC coil?

["Kevin Ottalini" <ottalini-at-mindspring-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Benjamin:
	The output from this has to be AC since the neon doesn't like DC.
The bad and the good thing is that the frequency is probably from 20KHz
to 40KHz.

The bad thing is that it would be difficult to get this to work as a
traditional AC drive to a TC ... a breakrate of 20,000 BPS could be
achievable with a very, very small capacitor and a static gap, but
the output from the secondary (my best guess) would be disappointing.

However, the good news is that you could put a full wave rectifier
on the output and build a DC drive for your coil (still AC out of the
secondary though).

The power requirement for a 9kv, 30ma inverter is 270 watts, or about
22.5amps from a battery or other DC supply ... a bit hefty and certain
to bring a car battery to its knees in short order.

The DC voltage output from the rectifier will be 1.414X the 9000VAC
input, or a max of about 12.7KVDC ... more than enough for a small
coil.  The 270 watts is a bit low, but if you build a small rotary
gap with a variable speed control, it should work ok at lower BPS.

All in all, it should work and might give you a very interesting
project.

Take a look here for a schematic of a 60Hz version DCTC and pics:

ftp://ftp.mindspring-dot-com/users/ottalini/highvoltage/DCCOIL/DCSCH2A.PDF

Just substitute the transformer and autotransformer with your DC
inverter and the DC power supply.

One problem (or not) is that unless you build a variable DC supply
for the inverter, you will always be running at full power.  I don't
know if the inverter will work reliably at lower voltages, so that
would be an important step to see if this is the right supply to
use for a TC.

Safe coiling,
		    Kevin

----------
> From: Tesla list <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: DC coil?
> Date: Sunday, July 30, 2000 9:43 AM
> 
> Original poster: "Benjamin Ness" <bness-at-home-dot-com> 
> 
> Hello all,
>  
>     I am a 16 year old coiler, so far I have built a small TC using a
12/30 NST
> (this won me third place in a national science fair competition this
year!),
> and I am working on a 6x30 coil powered by a 9/60 NST.  However, I also
> stumbled upon a possible source for a portable DC coil:  A neon
transformer
> designed to power underbody neons on a car.  Input is 12 v DC, output is
9000v
> 30 mA, I'm not sure if it is AC or DC, I have to check it.  But if it is
DC,
> what changes would I have to make to the primary circuit?
>  
> Check out my webpage at <http://fly.to/budspage>http://fly.to/budspage
>  
> Benjamin Ness
> 
>