Homemade X-Ray Machine: Liftoff

[AutogolazzoJr]

Well, after 5 or so months of posting odd questions on the forum, it's finally done.
I got the idea from this:
http://4hv.org/e107_plugins/forum/forum_viewtopic.php?106277.0
I used a Russian 2c2s tube to produce x-rays. For the high voltage, I used dual flyback transformers with two zvs drivers, with secondaries in series and 5+5 primaries, each primary going to its respective zvs driver.
The total generated voltage is around 50kv-70kv. The voltage was able to jump from an alligator clip and a ~20 gauge wire spaced 7.5cm apart. Yes, I was shocked by it. It hurt.
The 50kv was applied to the 2c2s tube in series with a ~.8Mohm resistor. With the power supply turned down to about 25kv, the geiger counter went off like crazy, but their was no illumination of the x-ray phosphor screen. With maximum power (30v through an LTC3780) it dimly lit the phosphor and produced hard x-rays (penetrated aluminum foil).
Sadly, both 2c2s tubes burnt out and the ltc3780 module was fried. I hope to be doing more work on this project. I have ordered 2 more 2c2s tubes and an american 2x2a.

UPDATE 6/10/20: It's been quite a while since i've touched this project, but I felt like detailing what I actually did. So, I used two of these for the power supply.

Both of these were fed (in parallel) by one of these boost converters.

I adjusted it to output 30v and as close to 20A as possible.
The flyback transformers were connected in series and the russian 2c2s tube was connected in reverse polarity (anode grounded, and all of the cathode pins connected to hv).

Gallery: https://imgur.com/gallery/BbXQRhR

[AutogolazzoJr]

BTW: inverse polarization was used, with the anode grounded and cathode to HV+.
These clips are blurry, but I swear that the image on the phosphor was sharp.


https://www.youtube.com/watch?v=QtNm9qtkJQ4&feature=youtu.be

[KE5FX]

Keep up the good work, and don't be this guy.

I'm sure you know to be cautious when using a Geiger counter to check for the presence of X-rays, since the tube can saturate.  But for the benefit of those following along at home: if the counter ever goes completely quiet, it means that either your HV supply has broken down, or that your DNA is in the process of doing so. 

[AutogolazzoJr]

I've heard of him. I hope my fate isn't the same as his. From now on, all tests will be behind lead or remote.

[AutogolazzoJr]

https://www.ebay.com/itm/DC-DC-Converter-10-12-15-20A-150-250-300-400-1200W-Step-up-Step-down-Buck-Boost/382219150784?_trkparms=pageci%3A712b3957-27fc-11e8-8f5d-74dbd180804a%7Cparentrq%3A2796433f1620a861f027772afff92151%7Ciid%3A1&_trksid=p2481888.c100675.m4236
Is this a good replacement for the ltc power supply? Does it really supply that many amps?

[james_s]

It's fun to experiment with various tubes, but if you just want to take nice xray images you can buy complete dental xray heads on ebay. The older iron transformer type are fairly easy to drive, and the heads are well shielded so they are a lot safer than a bare tube. Either way be extremely careful, xrays are no joke, you can easily cause real harm to yourself or others and get in a lot of trouble from the authorities.

[Bud]

A mix of the topic Subject and your age scares hell out of me. I am hoping you understand what you are doing.

[Cyberdragon]

https://www.ebay.com/itm/DC-DC-Converter-10-12-15-20A-150-250-300-400-1200W-Step-up-Step-down-Buck-Boost/382219150784?_trkparms=pageci%3A712b3957-27fc-11e8-8f5d-74dbd180804a%7Cparentrq%3A2796433f1620a861f027772afff92151%7Ciid%3A1&_trksid=p2481888.c100675.m4236
Is this a good replacement for the ltc power supply? Does it really supply that many amps?

Beware! It says the internal heatsinks are not good enough for the max current (for all of them), so you'll need fans.

You don't need two flybacks, you can use a diode-capacitor multiplier. You can also use spark gaps (Marx generator). The current limit for the tube might also need to be higher, try several megs. You could also have a current regulated supply (and also thermal cutouts) for the driver transistors if you want to go fancy.

http://uzzors2k.4hv.org/index.php?page=tubexray

P.S. Speaking of Ebay X-ray machines...how much are you willing to spend? Because this is an absolute bargain (and would be a lot safer).

https://www.ebay.com/itm/Belmont-Dental-X-ray-Head-Model-065-Type-BE-WK-with-Beam-Limiting-Device-/273071198127?_trksid=p2385738.m4383.l4275.c10

It says "tested working" So I assume it has a working tube already in it. Runs on 65KV at 10mA.

[AutogolazzoJr]

Thanks! I can rig up a fan to cool it off. I only turn the thing on for a few seconds at a time, anyway.
The dual flyback system seems to be working fine. It can put out tons of current and voltage without arcing over internally. A cw multiplier is not an option because the flybacks have internal diodes. I will be using more current limiting in the future.

That x-ray tube belongs to someone who doesn't care about getting in trouble with the Feds and has a little less life to live. Quite a bargain though.

[Teledog]

There's some info on DIY X-ray machines in the 1960's Scientific American "The Amateur Scientist" book.
Had a used dental X-ray machine in the garage..gave it away (used to work for a med supply co)
I might suggest using old school "intensification screens"..they light up & you'll need substantially less power/time to expose film/see an image
Dentists "are supposed" to replace their panoramic intensification screens every few years..maybe ask yours for old ones (assuming they haven't gone digital/CCD ..as a lot do now)
I'm old & don't care anymore....BUT, if you're young,.. I'd suggest a lead apron when playing.

Edit: X-ray heads typically run for less than a second - between 2-3 minute cooling periods, depending.
The HV transformers are typically in the head and submersed in oil
If there's oil pissing out of a dental X-ray head..it's been over-run/overheated & toast!
Don't ever expect the X-ray to run longer than 3/4-1 second every few minutes,

[AutogolazzoJr]

 My phosphor screen is 3m trimax 12, which (I believe) produces sharp images at the cost of dim image. Perhaps this would work better? The only downside is that is is quite expensive from Russia. https://m.ebay.com/sch/i.html?_odkw=x+ray+intensification+screen&_from=R40&_trksid=m4084.l1313&_nkw=x+ray+intensifier

[Cyberdragon]

Modern X-ray machines can take more images than that. When I'm at the dentist they take at least four images in a minute, and that's with a 90s machine. But still only pulses, at some sort of high frequency.

https://hackaday.io/project/3665/logs

[james_s]

It all comes down to anode heat capacity. You can run a tube for much longer periods at low current but if you crank up the kVp or mA then the exposure has to be shorter to avoid overheating the tube. There is also a heat capacity of the whole head, they are filled with either oil or in some cases SF6 which absorbs heat from the anode and dissipates it in the case.

Dental heads are probably one of the safest sources for amateur xrays, they are relatively low power and very well shielded and the HV is self contained. They can still be very dangerous if used carelessly but it's much safer than playing with bare tubes. Xrays are very high energy photons, they can burn your skin very much like intense sunlight, except that they pass through you and burn all the way through, and smash up your DNA in the process. You don't want that!

[AutogolazzoJr]

Some more results of gameboy cartridges:
All 1 second exposure, f2.8, 1st image 3200 iso, 2nd 1600, 3rd & 4th 800.




https://imgur.com/a/JReAx

[Mr. Scram]

What are the other parts we're looking at? Looks like some kind of carpet in a closet.

Other than that, very cool! And like everyone says, be safe! These are very cool experiments, but a false move can be costly. Be mindful of every step you take.

[james_s]

Also be very mindful of what is behind your target. Xrays will go right through the wall and through the neighbor's house. You need to be absolutely certain you aren't exposing anyone to radiation, that can get you in very big trouble.

[David Chamberlain]

Think you just voided the warranty on those cartredges. But yeah very interesting - and yes be safe.

[AutogolazzoJr]

Anyone know where I can find small X-ray tubes for cheap like this one: https://www.youtube.com/watch?v=ADAOFMsQi2U?

[james_s]

That's a dental xray tube, you can get the whole heads on ebay often for under $100. I'm not sure why people take them apart, it's much safer to use the dental head intact as it has all the shielding and insulating oil or SF6.

[Cyberdragon]

Just make sure you get one that's new enough to not have PCBs or anything else too nasty in it.

[james_s]

I wouldn't worry about it, most of the stuff you'll find is 80s or later which is not going to have PCB oil. Even if it's an old one that does, it's not going to hurt anything as long as you leave it alone. The problem with PCBs is that they are extremely stable compounds that don't break down when they get in the ground so they end up in water supplies. It's not particularly dangerous stuff to handle but you don't want it in your food or water so disposal can be an issue.

Whatever the case just don't take the head apart, the oil filled ones are messy, the SF6 (gas) filled ones you'll let the gas out if you open the head. Either way the transformer will flash over if you try to run it in air. Also don't try to run one directly off the line, usually you need about 80V on the primary for full tube voltage and something similar on the filament. If you temporarily remove the aluminum filter from the output you can adjust the filament voltage by eye, it should glow about like a low wattage incandescent lamp, white hot, not the dull orange of most thermionic filaments. This is because an xray filament is pure tungsten.

[AutogolazzoJr]

Is there any way to make the pictures sharper? any new form of imaging? The problem with the tube is that the x-rays diverge at a very wide angle. Prehaps moving the x ray source or thing being imaged a bit, and only having a small part of the object imaged? Kind of like a raster scan? Maybe there is a way to focus the x-rays? Thanks.

[SilverSolder]

To sharpen the image - maybe try making a "pin hole camera" for X-rays?   Place the tube behind a lead plate with a small hole in it?

The idea is to make the X-ray source more like a point source, not a laser beam.

[Wolfram]

You have to figure out where your lack of sharpness comes from. If you use a rectifier as an x-ray source then the x-rays will be coming from a broad area, leading to significant geometric unsharpness. To get the best possible results, place your imaged object as close to the screen as possible, and place the source as far away as practical. A pinhole to reduce the apparent source size as suggested by SilverSolder would also work. Both of these methods will of course also reduce your light yield, so you will be limited by camera noise and overheating of the tube. As suggested by James, a dental x-ray tube will yield superior results, I've attached some sample images taken with a dental x-ray tube on film and cassette screen.

[james_s]

Sharpness is a combination of anode spot size and anode to subject distance. You can't do anything about the spot size as that's part of the tube design but you can move the tube further away. You will gain sharpness at the expense of needing longer exposure times.

There are other factors too, the grain of the phosphor screen, mammo screens have finer grain but they require longer exposures or more power. If you are imaging the screen with a camera that could be your limiting factor too.