At 12:20 AM 8/16/97 -0400, you wrote:
>I hate to restoke the flames, but I always wanted to build this home-made
>X-ray machine that uses a Van De Graff generator and a foil-covered light
>bulb. Anode goes to  the filiment, and cathode to the covering thin copper
>foil. It was described in the book "The Amature Scientist" by Stong.

My advice is don't do it - X rays are nigh on impossible to direct or
focus without specialised equipment, making your own is not recommended,
the resulting X-rays could be at all sorts of frequencys (energies) and
scatter very wildly on any homebrew setup  !

>BTW, I've had a rad safety course from a national laboratory, where I
>moderated neutrons. They told me I was idealy suited, because of my
>exeptional skull density. I would just like to know what voltage, current
>and time to deliver the same energy dose as UV erasers do.

Its not the 'energy dose' its the frequency you want, ie X-ray frequency
that is low enough to erase a cell BUT high enough to see the plastic
PIC encapsulation as mostly transparent, then you have to keep the beam
focused AND have a high enough flux. In theory with the bell shaped
distribution of frequency to erase a PIC at UV you want to select a
frequency that is still a couple of standard deviations away from the
centre UV frequency - this puts it into low frequency X-ray - only just !

I'd hate to see the X-ray shadow of your thick skull on the ceiling,
so please reconsider this very carefully. I was radiation officer
whilst chief engineer of a company that used Cesium 137 and Cobalt 60
sources for nucleonic ore flow measurements and it ain't worthwhile
messing about with radiation unless you are VERY WELL INFORMED and
know the risks REALLY WELL.

Far safer is to use an old B/W monitor, set the EHT high, fiddle the
deflection and direct it down and leave he whole thing in the garden
shed out of anyone's way.

rgds

mike
Perth, Western Australia