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Re: [TCML] current limit system and X-rays



X ray generation will not occur until you reach at least 15KV. This is just simple laws of physics in being able to accelerate electrons fast enough to be able to produce x rays.

Almost the universal voltage for most X ray work is 40-60 KV.

Using an NST will not work unless you can series them, even a 15KV transformer will be pushed. An NST is self regulating in that it produces a high voltage to strike the discharge in a tube and then as the tubes starts drawing current, the transformer lowers it voltage accordingly to maintain the discharge. This is one reason folks remove the shunts so they have a constant HV to fire a TC (of course you get a LOT more current too which is what makes coils sing!).

I ran a small Coolidge X ray tube one time using two NST's in series and got low level X rays, enough to light a fluorescent screen but not enough to penetrate a finger to see the bones. Of course when I turned the lights back one, the entire floor of my room was full of smoke where one transformer arced internally and was having fun melting and burning the tar!

NOW, NEVER , NEVER, NEVER run a Geissler tube on a NST!
Geissler tubes are like neon tubes, once they are lit, they will draw as much current as can be supplied. Using a NST will supply to much current and will overheat the electrodes and destroy the tubes. Most small Geisslers will run fine on 2KV and larger tubes and small Crookes tubes will run on a Model T spark coil unless you have a tube with an X ray vacuum, then you need a spark coil that will put out at least a 2" spark.
A Model T coil will run most Geissler tubes and is what I use for most tubes.
In addition, a Geissler or Crookes tube needs to run on DC to get the desired effects as they are polarity sensitive. Neon sign tubes have a transformer sized to the tube length so as not to overdrive them.

Frank

At 08:03 AM 9/25/2010, you wrote:


--- On Fri, 9/24/10, amir gh <mamout.72@xxxxxxxxx> wrote:

> can anyone explain if there's anyway to remove current
> limit system in NSTs?

It is possible, but it isn't easy. NST cores are shunted. That is, small bundles of laminated iron are tucked into the core windows between the primary and secondary coils. These iron shunts add a large leakage inductance to the NST, resulting in fairly rigid current limiting. Removing some or all of the shunts will increase the output current. To remove the shunts, the NST must be released from the block of tar or resin it's potted in. This can be a messy, time-consuming process. Also, the depotting effort sometimes damages the fragile NST windings. It is do-able though. Many members of this list have done it successfully. Search for "depotting" in the WWW.pupman.com archive for more info.

> and can i connect a simple geissler tube to my coil and
> ground to produce
> X-rays?

A Geissler tube is not an X-Ray source. It is a glow discharge tube filled with rarefied gas--similar to a neon sign. So no, you can't make X-Rays with it. To make X-Rays, you need a Crookes tube, a cold cathode X-Ray tube, or some other sort of "hard" vacuum tube. Assuming you employ a proper tube, NSTs do develop enough voltage to produce soft X-Rays, according to Wiki:

http://en.wikipedia.org/wiki/Crookes_tube

> tnx for helping again.
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla

Cheers,

Greg




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