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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
As you won't be making radiographs of human beings who might blurr your images by moving unless you keep exposures short, you could make your life easier all round by reducing your anode voltage to, say, 40keV, or even less.
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
I don't know what Grenadier is planning on radiographing, but if it is standard household objects like clocks, remote controls and the like, then 40kV is going to be a bit on the low side, even thin metal will block most of the radiation. In addition, the radiation output of the tube is going to decrease drastically at such low voltages, as the glass will block most of the radiation. You will need very long exposure times, and reciprocity failure of the film is going to make things even worse.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Anders M. wrote ...
I don't know what Grenadier is planning on radiographing, but if it is standard household objects like clocks, remote controls and the like, then 40kV is going to be a bit on the low side, even thin metal will block most of the radiation. In addition, the radiation output of the tube is going to decrease drastically at such low voltages, as the glass will block most of the radiation. You will need very long exposure times, and reciprocity failure of the film is going to make things even worse.
I hadn't thought of someone using X-rays to view something which would be better seen by means of a desk lamp and screwdriver, but in the examples you've given, I couldn't disagree with you. And you are right to draw attention to the wavelength limitations of glass beam windows.
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Those seem to be the kind of things hobby radiographers take pictures of. Hobby radiography is usually more about getting interesting pictures than finding out what's inside things.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Anders M. wrote ...
Those seem to be the kind of things hobby radiographers take pictures of. Hobby radiography is usually more about getting interesting pictures than finding out what's inside things.
I'm sure you are right, Anders. Why set anyone's horizon higher than metal and plastic?
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
I don't see why you keep fussing about the expense of the C&W multiplier, Grenadier. As long as size isn't an issue, being cheap on components is easy. I've made a dirt cheap 120kV C&W which can supply ample power (I've taken it up to 1500W), for under 15 dollars. Roll some capacitors, buy a few hundred UF4007 diodes on ebay and spend many hours soldering.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
3 lettes on my keyboad ae boken, can you guess ich ones? I'm sick of using on sceen keyboad so please bea ith me.
Yes I plan on taking x-ays of household objects, so 40kVp ould be too lo fo my puposes.
I'm going to ty an ignition coil based cicuit befoe I ty a C multiplie, but the olled foil caps ae a geat idea. I can't ty thi no though, mainly because I don't have enough diodes.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
A reality check; 70 kV @ 3 mA = 210 W, 210 W / 11V = 20Adc @ 100% efficiency, say 30Adc realistically. You'd be lucky to get 5min. from a 12V 6.5 AH battery. And it will give very short battery life too.
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Designing a variable HT PSU
