100 kV switcher

[peranders]

Quote:

Originally Posted by Nixie Thanks for your concern, peranders, but discussing this here would only decrease the chance of me harming myself.

I'm not so sure about that. Do you by any chance have measurement equipment? Have you worked before with 100 kV and mA? I have GREAT respect for such eqiupment since I have worked with it.

 

[Nixie]

Don't tell me to go to college; I'm a grad student (though not in EE, but CS -- I'm working on tomography algorithms, which inspired me to take my own projections by reading a scintillation screen with a digital camera, and then do 3D reconstruction on them). I've worked with somewhat lower, but still high voltages of 5 kV at 300 mA for plasma experiments -- I even wound my own transformer and choke for that (besides messing around with 30 kV low current from flyback-based supply). Never had a problem, other than burning up test load resistors. The only times I've been electrocuted was when starting out with headphone tube amps at 2-300 V (less fear-inspiring, I guess, than a couple of thousand joules in the filter capacitors of my plasma supply).

I've not worked with X-ray radiation before, but so what. It's not like I intend to operate the thing while anywhere near it.

 

[skyskraper]

im not calling you dumb or anything. nor am i implying that you are incapable of what is required. i was merely saying the type of knowledge that would be useful to you is probably best acquired during tertiary or more likely post grad level.

id love to see what the parents of the poor kid who typed "DIY X-RAY" in to google, would have to say to head fi (or other forum) after their 16 yr old zaps themselves based on info found in a thread like this

 

[kevin gilmore]

a few more pictures

http://gilmore.chem.northwestern.edu/sxray2.jpg

used tubes
http://gilmore.chem.northwestern.edu/sxray3.jpg

what xrays do to pure copper at 3000 hours
http://gilmore.chem.northwestern.edu/sxray4.jpg

what it takes to do this safely
http://gilmore.chem.northwestern.edu/sxray5.jpg

camera stand version (no longer considered safe and NOT in service)
This is what nixie (ahem prune) really wants.
http://gilmore.chem.northwestern.edu/sxray6.jpg

spellman supply (my favorite)
http://gilmore.chem.northwestern.edu/sxray7.jpg

and the xray cable and connector
http://gilmore.chem.northwestern.edu/sxray8.jpg

death on a stick (picker transformer based unit from the late
1960's. Still works great. No one wants to mess with this thing
anymore including me) (more than 700 lbs and filled with liquid
PCB's)
http://gilmore.chem.northwestern.edu/sxray9.jpg

 

[jamont]

Quote:

Originally Posted by kevin gilmore death on a stick (picker transformer based unit from the late 1960's. Still works great. No one wants to mess with this thing anymore including me) (more than 700 lbs and filled with liquid PCB's)

Ah, Picker X-Ray! Brings back fond (and not so fond memories). As an undergrad, I worked for an X-ray crystallographer who had a computer controlled Picker diffractometer of similar vintage (the computer in question was a PDP-8 - for anyone not familiar with it a Palm Pilot would be a significant upgrade). The really scary machine was the old GE with the precession camera...

 

[Nixie]

Nice pics. So you wouldn't have a spare you can sell me that's under 80 lbs? I need a pretty small duty cycle of bursts. Some guy offered me high frequency switcher-driven X-ray transformers, but they are 20 kW and I couldn't power them from house mains...

 

[kevin gilmore]

jamont writes
Ah, Picker X-Ray! Brings back fond (and not so fond memories).

This is the seriously upgraded unit. It has a pdp-11

I think you are showing your age. pdp-8 is very early 70's.
Which would put you at about 55 years old...

nixie just does not get it. If you really want to do pulsed x-rays
go and knock over a dentist and swipe theirs.

 

[jamont]

Quote:

Originally Posted by kevin gilmore jamont writes Ah, Picker X-Ray! Brings back fond (and not so fond memories). This is the seriously upgraded unit. It has a pdp-11 I think you are showing your age. pdp-8 is very early 70's. Which would put you at about 55 years old...

Now why did you bring that up??

 

[kevin gilmore]

I thought i was one of the oldest guys around here...
guess not...

Actually uncle phil is mid 50's i think

 

[Nixie]

There's a portable on eBay using a marx generator as a pulsed supply, but he's asking too much.

 

[eric343]

I saw just the thing you need this past weekend. It was being sold by the University of Washington at a surplus auction... I think it went for $150 or so.

http://www.audiogeek.net/images/xray

Apparently it's from the 1920s. Sorry for the bad quality -- all I had was my cameraphone.

 

[Nixie]

I wonder if neon sign transformers have good enough insulation to put two 18kV ones in series, and then drive a full wave doubler. There's also a 100kV 300mA transformer on eBay that's only 60 lbs, but the house wiring can't handle that. Unless I drive the primary with switched capacitors to get a burst mode.

 

[eric343]

Let me get this straight...
100kV * 0.3A = 30,000W / 120V = 250A (!)

Wow. I'm guessing it's a three-phase transformer!

 

[Nixie]

The guy said it's used for burst mode, not continuous. Two primaries (parallel or series depending on European or North American mains voltage), two 50 kV secondaries that can be put in series for 100 kV. It would be easy for me to make a driver that charges a big ass 120 V capacitor and discharges it periodically for burst mode, say 10% duty cycle for 3 kW -- fine for house wiring.

Too bad he wouldn't sell it immediately, 8 days left in auction I'll probably be outbid