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DIY Radiography

Sigurthr

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Hey all!

I finally placed a notch in my belt that has been more than a decade in the making! Full write up can be found here and is worth a read if you're interested in the technical aspects.
Link -> Sigurthr Enterprises: Portable DIY X-Ray Source & Radiography

I'll save casual onlookers the read though and just put up a few of the photos here.











 

Down with Umbrella

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Incredible Sigurthr, this is taking "DIY" to the next level.

I'm glad to read the further details on the blog post.
It's an excellent feeling to see years of work come together.

PS have you slept tonight??
+ rep when I can
 
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Sigurthr

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Thanks!

PS have you slept tonight??
Haha, nope. That's normal though, I don't have fully functional circadian rhythm, ties in with my other endocrine issues. I typically need to get 10-16hrs of sleep per night to keep my Addison's in check, but once a week I wind up getting 3-6hrs instead as I have to get up on time for my weekly injection. Some weeks with lots of appointments I end up getting 3-6hrs for three nights, and I almost always need a week or two to recover after. So the subsequent nights I try to play catch up with increased sleep time. Anyway, got up at about 6:30pm tonight, it's almost 7am now so I'm starting to wind down. I expect to be asleep before 9am.

I spent entirely too long documenting and reporting, but it's very important to me that I get it done. I've failed to document too many projects over the years and before I know it I don't remember the details and all is nearly for naught. Something as big as this I wanted to have every detail recorded.

I think I started doing the write up around 10:45pm, finished it around 5am, though I did take two one-hour breaks. Writing never was my strong suit as far as time is concerned, but I like to think I'm reasonably proficient at it. I've gathered a lot of knowledge over my years, often unable to recall it on a whim unless prompted at the right time. Eventually I need to make more blog posts detailing various subjects, but it's hard to allot the time and dedicate the effort.
 

ped

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Outstanding work (again) Sig .
I'll read the blog tonight.

When I was looking at the pics, I was thinking..Oh, a China ZVS, oh, a China 12V RC switch...Damn those Chinese building all the stuff we need :D .

Thanks Sig , REP when it'll let me.
 

Sigurthr

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Outstanding work (again) Sig .
I'll read the blog tonight.

When I was looking at the pics, I was thinking..Oh, a China ZVS, oh, a China 12V RC switch...Damn those Chinese building all the stuff we need :D .

Thanks Sig , REP when it'll let me.
Thanks! I definitely think you'll enjoy the blog post too, I did my best to make it widely approachable and intelligible, if a bit wordy. I intentionally left out explanations of the construction/design/functionality of the ZVS and CW Multiplier sections. I figured they would be too esoteric for most readers who don't know about them already, and not really germane to the topic.

Haha, I think everything except the tube itself (Japanese) is Chinese, actually. As I say in the blog; a good engineer knows when to use an off the shelf solution. The transformer is one of Fiddy's, from China. The box/tupperware is bought at Walmart, so that's Chinese. Lipo is Chinese. Electrical components for the multiplier are eBay special... so def Chinese. The hardware is definitely Chinese, a mix of amazon and eBay. I wouldn't put it past the mineral oil that it too is from China, haha. While I could certainly have DIY'd the remote and zvs, there's no practical point when you consider the time and effort it takes. You can't beat Chinese cheap labor, from a non-humanitarian perspective.

Also, I no longer have a local supplier for wire, solder, protoboard, or any components at all, so I try to save them all for must-use purposes only. This lack of availability, combined with restricted budget, results in China special results.
 

ped

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One question, can X-Rays be visualized in any way, so that you could see the emission "live" ?

EDIT, that's a 1KW ZVS ain't it? I have one of them for my induction heater, couldn't you have got away with one of the smaller ones like the one I use to drive my tube?



Ped
 
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BowtieGuy

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Wow, amazing work, Matt!
The talent level of members like you never ceases to amaze me!
I looked through your blog and saw your photos, very cool. No more selfies though! :D
:gj: +rep
 
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Sigurthr

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One question, can X-Rays be visualized in any way, so that you could see the emission "live" ?

EDIT, that's a 1KW ZVS ain't it? I have one of them for my induction heater, couldn't you have got away with one of the smaller ones like the one I use to drive my tube?

Ped
You forgot to translate from eBay Chinese click bait... It's a ~300W ZVS when used on 24V, the 1kW rating is just made up. The reactive power in the tank under no load; about 150A @ 30V for 13.8V input.

As for Fluoroscopy (live radiography); tried it but the image is too weak with this XIS, will try with the new ones coming.

Wow, amazing work, Matt!
The talent level of members like you never ceases to amaze me!
I looked through your blog and saw your photos, very cool. No more selfies though! :D
:gj: +rep
Thanks! Yes, definitely no more selfies (autoradiographs)! Hehe.
 
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Cyparagon

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Neat project!

A few questions if you feel up to them: How did you measure the tank's current? The multiplier's current? The multiplier's output voltage? What frequency is the transformer operating at? ZVS drivers I've seen in the past have a center tap. How is this one different? Is there a rough schematic of it somewhere? Does that teeny RF switch have an internal relay, or what? Have you checked that it can reliably handle the 15A DC?
 
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ped

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That's me well and truly told :crackup: , of course I used the quoted rating to differentiate between the two :)

Ok, Question (V2.0)

Could I use one of the cheaper ZVS's, or do you have to use the one with the bigger tank?
 

RedCowboy

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Very cool, and yes it's always good to upsize based on Chinese ratings.
 

Sigurthr

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Neat project!

A few questions if you feel up to them: How did you measure the tank's current? The multiplier's current? The multiplier's output voltage? What frequency is the transformer operating at? ZVS drivers I've seen in the past have a center tap. How is this one different? Is there a rough schematic of it somewhere? Does that teeny RF switch have an internal relay, or what? Have you checked that it can reliably handle the 15A DC?
One of the reasons I bought this ZVS unit is it uses Marko's revision of the Mazzilli ZVS circuit; two input inductors allow you to pull each end of the parallel LC with fets instead of pulling across alternating legs of a center tap. This means it can be used with two-terminal primary transformers. See: http://i.imgur.com/Q3VqOhO.png

Tank current was measured with my scope's current transformer probe, and I blew the 10W burden resistor to pieces in about 1.5sec of connection, lmfao. Had to replace it after that so I'm not going to redo the measurement. It was in the ballpark of 150Apk. It was connected to the supplied air core primary for induction heating at the time of measurement, so that current measurement isn't really valid in flyback/transformer use like I have it set up now. Aside from when designing and assigning parts, knowing the circulating reactive current isn't really important.

Multiplier current is variable based on filament voltage (conductance/impedance of the tube). Same for multiplier voltage. However, there's a rough guesstimation we can do: the ac flyback isn't operating in flyback mode, as it is driven in ZVS with a resonant primary LC circuit. With 12V input tank voltage rises to ~30Vpk. The transformer's secondary is 3000turns, primary is 6 turns, resulting in a 500:1 step up ratio. 500 x 300 = 15kV. Empirical spark gap tests show this is within ballpark accuracy. 5 stages of CW Multiplier = 75kVpk ideal output. I apply a 5% reduction/loss per stage as a rule of thumb for a decently designed CWmult under nominal load (load the mult is designed for, in this case 2.5mA), so 75k x 0.75 = 56.25kV. Judging by the penetration ability of the resultant x-rays this looks to be ballpark accurate as well. Measured input power is 152W, 56.25kV @ 2.5mA = ~140W, so again within reason.

On this transformer it resonates at 40KHz. With the supplied air core primary it resonated around 102KHz.

RC Relay Module has an internal 30Vdc 10A / 240Vac 10A relay. I'm pulling a little under 16A through it, but my ON times are never more than 10sec, so I'm not too concerned with the thermal loading. I'm sure internal sparking from back EMF will wear out the contacts faster than normal, but I'll just whack a new relay on it when that happens. Before using it with the x-ray unit I gave it a solid testing on my bench switching 15A 15V loads into a dummy load (100W 1R resistor in water).

That's me well and truly told :crackup: , of course I used the quoted rating to differentiate between the two :)

Ok, Question (V2.0)

Could I use one of the cheaper ZVS's, or do you have to use the one with the bigger tank?
it depends what you want to do really. If you're going to be driving a 150W load like I am you'll want as much power handling as you can get. I mean I could remove two rows of tank caps and it would resonate at a better (higher) frequency, but I'd be tripling the current flowing through the remaining capacitors, which would probably pop them. If you don't mind a center tapped primary ($#@%ing hate them for some things) you can use a standard Mazzilli ZVS driver which is cheaper and easier to find than Marko's revision. Still though, I think this driver with coil was only $40 shipped. Fiddy grabbed one and then alerted me about it, and I grabbed one too.

(not directed at the above two quoted gentlemen.....)

I do want to reiterate to anyone thinking of replicating this or doing anything with an x-ray tube other than using it as a desk lamp with the filament ONLY..... THIS IS INSANELY DANGEROUS. Don't try it!

I dug out my calibrated ion chamber today to do some Exposure Rate measurements... and boy fellas, let me tell you, I'm regretting sticking my hand in the beam path.

10 ROENTGEN PER HOUR EXPOSURE RATE.

Yeah, I only had a 4sec maximum exposure, but damn, if that doesn't scare your scrotal hair off I don't know what will. Granted that comes out to about 3mR/sec, so I probably only got about 12mR total dose to an extremity. It's been too many years since I studied health physics and I can't remember the conversion procedure for hand-only dose to body dose (but it isn't upscaling, so using face value is good'nuff). So I estimate I dosed myself with about 15mR total radiation to date. That's about 1000 hours worth of background radiation in five seconds.

Anyway I video recorded my exposure rate tests and I'll put the video up shortly.

By the way, the battery in my saturation-proof GM detector fell below the undervoltage limit, which causes false positive readout. This happened while I was in the room setting up after arming the x-ray unit and I shat some bricks as I ran away, lmfao. Lesson learned. I *really* want a good lead apron, too bad they're about $120. I just have to settle for ALARA practices.
 
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ped

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Thanks for the information.

I'm not a fan of the center tapped ZVS's myself, I have one of the "1KW" ZVS's (same as in you're pics) , I haven't tried it with a FBT yet.
 

ped

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What was the smoke like effect in the tuppawear box near the end?
 

Sigurthr

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What was the smoke like effect in the tuppawear box near the end?
High voltage electrostatic propulsion of the oil bath! There's a jet from anode to cathode and from higher to lower potentials.

One of the best things about doing physics projects is all the tangential phenomena that you get to experience and learn about. I knew of the effect beforehand but had no idea it was so palpable!
 




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