Re: X-Ray Transformer HV Power Supply

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


Thanks for the great info.  This transformer is coming right out of a dental
x-ray head and isn't nearly as heavy as your 1000 lbs behometh!
The whole assembly is about 50 lbs so the transformer probably isn't that
big.  I'm not sure how useful this transformer will be (maybe run only 1-5mA
continuous?), but it will be
fun to take this thing apart and experiment a bit with the transformer.

Thanks

The Captain


 > Captain,
 >
 > I have a 140 kVP, 500 mA x-ray transformer that tips the scales at
 > nearly 1000 lbs. and I am just using it to drive a wicked Jacob's lad-
 > der. It had the rectifier assembly inside it when I got it but the recti-
 > fiers quickly burnt out when I started shorting the outputs, even with
 > the input to it well ballasted. I finally had to pull the core out the
tank
 > and take out the rectifiers and just use it as an AC HV supply. The
 > diodes that come in these x-ray trannies are very physically small
 > for the > 100 kV at several hundred mAs that they can put out. Of
 > course they are designed to be submerged in oil during operation
 > and for very low duty cycle (usually < 1 second for the x-ray expo-
 > sure). It seems to me that you would almost have to have your rec-
 > tifier assembly submerged in oil just like the transformer but that
 > it would require a considerably more robust rectifier for continuous
 > power supply/ and or capacitor charge duty. I have 11 of those 5 kV,
 > 2 amp hockey puck style diodes that I am currently using (all of them)
 > as  rectifier for my (2) seriesed 7200 volt PTs that I use to charge my
 > (2) 10 kV, 100 uF coin shrinker/can crusher caps. I think this style
 > of diode would probably work for rectifying an x-ray trannie's output
 > if you had enough of them (like at least 40 per leg) and they were al-
 > so submerged in oil.
 >
 > One thing you need to be well aware of when dealing with x-ray trans-
 > formers is that their output voltage is very high and has enough current
 > to be EXTERMELY DANGEROUS. Mine will easily jump the ~ 8" gap
 > at the nearest approach of the sparking rails of my Jacob's ladder and
 > as I run the variac up, it begins corona hissing like 100 angry rattle
 > snakes before the 8" gap finally breaks down. This hiss sounds quite
 > wicked and could also be compared to the sound of frying bacon. I can
 > actually feel the "electric wind" in my face or on the back of my hand
 > through the grounded chicken wire cage around it when the voltage is
 > turned up to the point just before spark breakdown between the Jacob's
 > ladder rails (probably at least 2 ft. away from the nearest HV terminal,
 > with the grounded chicken wire cage between me and the HV terminal)
 > This is certainly not for your beginner HV experimanter ;^0
 >
 > Be safe,
 > David Rieben
 >
 >
 >
 >
 >