XRays and electronics

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Simple question. Will xrays damage electronics? Say if I was to xray the
circuit in my car key?

Thanks,
Mike



Re: XRays and electronics



"Michael C"
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**  Like hell it is.


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**  Google not working where you are ?

 http://www.spaceref.com/news/viewpr.html?pid52%19




.........  Phil




Re: XRays and electronics


I think you'll find that high energy radiation/particles will discharge flash
and
EPROM memory cells over time. If the micro in your key is a ROM micro this isn't
a
problem, however the rolling code will be stored in EEPROM.

Also, remove power (the battery) whilst doing this. The X-ray may induce
malfunctions
if power is applied at the time.

-Andrew M

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circuit in
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says...
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Depends on a heap of factors, frequency, intensity, distance from source etc,

Some EPROMs will discharge their cells under high UV but not low X-ray
but will do so under high X-ray or gamma rays. There are all sorts of
solid state issues, the best analogy is, you can push a tennis ball
into a piece of tissue and push it out of the way, ie changing from presence
to absence, or 0 to 1. But that same tissue will only have a small hole in
it when hit with a bullet, the average is that the tissue is still present
so a 0 etc. Solid state physics is repleat with effects like that but also
with the opposite effects, so it depends on the materials, whether the
X-ray photon strikes and ionises an atom or molecule sufficiently to
effectively vaporise the tissue etc (I wont stretch the analogy too far).

One interesting thing is that some OTP eproms can be erased with low level
X-rays over a long enough period and in the presence of a small bias voltage,
I have heard of a case where a b/w monitor had its scan arranged for a spot
size, the EHT turned up so X-rays were produce from a region of the centre of
the screen, this was hten used to erase or rather upset some cells on an
otp eprom so it could have part of its code written with a hack to dump
whatever code was left. This would take a huge amount of time, especially
as the erasing would be pretty random but I have also heard that some
security cells in the early days of OTP could be erased with somewhat
less energy than the rest of the array as those cells were in other regions,
suffice it to say these parts didnt last long in the market place...

When it comes to (essentially) fixed electronics where there are no EPROMs
or EEROMs etc only ROMS then I'd say its unlikely given the types of X-ray
sources most of us encounter at dentist, hospital or airport...

Wont compress any hydrogen well though ;-)

<chuckle>

--
Regards
Mike
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Re: XRays and electronics



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How long ago was that?. These days you can use a laser to read each bit
right off the chip, this is pretty common when reading embedded eeproms off
dead processors.



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says...
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Something like 10 years back, I recall it was a real messy low end
way to try to glean the contents, it was in one of the alt hacking forums,
seems it was only effective if you really had lots of spare time and lots
of chips to wade through...

Are lasers used that much these days, surely its not as simple as that,
I read a while ago about glass passivated coatings added to many secure chips
especially when SOI or SOS chips are prepared and before any encapsulation,
which I would have expected make life very difficult for laser scanning,
even in vacuo with electrostatic probes as the coatings effectively clouded
the field over the PROM array, think same thing used in FPGA and ASICs  ?

Getting the epoxy off is also no easy method unless you happen get some of
that Sulphoxide solvent which is highly carcinogenic. I certainly wouldnt
try it, these days techniques for data processing are so well known for
even the off the wall algorithms, so reverse engineering from known outcomes
using up to date tools would be more efficiently and open other opportunities,



--
Regards
Mike
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Re: XRays and electronics


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once, no, a million times maybe. x-rays aren't good for stuff...

cameras, walkmans, laptops, and even car keys go through airport X-ray
machines every day, I've not heard one report of damage.

Bye.
   Jasen

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Cameras no, the film in the camera maybe.

But then everything is digital these days.

Re: XRays and electronics


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the sign I saw posted said anything less than about 3200 ASA (most films are
100-400 ASA) wouldn't be adversely affected by the machine.

I've not noticed degredation in regular films after them going once or twice
through the x-ray machine.

--

Bye.
   Jasen

Re: XRays and electronics



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are

Of course they say that, they don't want to hand inspect every camera. It's
not their film after all.

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twice

Real tests have shown very slight fogging for well maintained X-ray
machines, or large amounts for old, poorly maintained ones.
Of course most peoples happy snaps are not that important anyway, so no need
for them to worry.

MrT.



Re: XRays and electronics


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Surely the xrays used at airports are significantly lower. Last time I got a
tooth xrayed they covered me in a heavy lead blanket and all the staff
vacated the room and hid behind a lead filled wall (not something that
filled me with confidence:-). They don't do any of that at de iport.

Michael



Re: XRays and electronics



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a

Which is all very amusing if you consider your brain to be important.
Of course you would not expect dental staff to be experts on X-ray radiation
though. My dentist can barely manage to get a usable image.

MrT.





Re: XRays and electronics


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I wouldn't say amusing :-)

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Getting an xray using film is very difficult and made more difficult by the
fact it takes 10 minutes to find out it didn't work. If the patient moves
the film can be no good. Digital sensors are much better because the result
is instant, the image can be lightened or darkened if it is over or under
exposed, the dosage to the patient is about 10 times less and there's no
chemicals. The image is also much larger (size of screen compared to a
couple of cms) and can be zoomed further. The only drawback is the $14,000
for the sensor (which is apparently just a CCD in a plastic case).

Michael



Re: XRays and electronics



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the
result

Absolutely, (and I saw that SC article too :-)
What I can't understand is why it's taking many so long to change. Some were
doing it years ago.

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Which is about a days work for many dentists :-(
Considering the cost of the X-Ray machine in the first place, it's peanuts.

MrT.



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I haven't seen that article.

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The machine that generates the xrays is only $8000 which I think is pretty
reasonable. Dentists do encounter a huge amount of cost running a practice
and don't end up with that big an income considering they are a doctor and
have started their own business. Their income isn't that bad either but
someone could start a restaurant and make a similar income with no
education.

Michael



Re: XRays and electronics



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I assume you have never tried running a restaurant then.
The *average profit* from a dental surgery would exceed the average profit
from a similar outlay restaurant by an order of magnitude at least.
And the number of dentists who go bankrupt^ is exceedingly small, unlike
restaurant owners.
(^ even when they do, it's usually because they lost it on the stock market
or horses!)

Of course they are well educated, but doctor/dentist income is controlled by
the number of people they let in to the course each year. *FARRRRR* less
than the number of applicants with high enough entrance scores. Limited
supply makes sure there is no competition.
In the restaurant industry, the over supply has the opposite effect.

MrT.



Re: XRays and electronics


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Don't be silly :-)

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How much do you think a surgery would make per dentist?

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They do say a dentist will never go broke practicing dentistry. :-)

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My point was it is possible, not even that difficult to open a small
business and compete on income with a dentist. I didn't mean to say that
everyone does but I think a reasonable well run business would. The problem
with dentistry is the dentist has to be there to do the work. Most
businesses are more open to expansion, once a dentist gets to 40hours a week
full time that's pretty much where it stops. Also, to be fair and make an
"on average" comparison you should include the la pochettas that started
small but now make millions.

Michael



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profit

Do tell us, but a it's lot more than a restaurant per waiter.

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See, you do understand.

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Sure it's *possible* to win tattslotto too, but hardly relevant.

Mr.



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What relevance does that have? Per owner might have some relevance.

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It doesn't mean they make a fortune.

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Silly statement really. The chances of a restaurant making as much as a
surgery are extremely good. Do the maths, a dentist might bring in $300 an
hour average and bill 30 hours a week for 48 weeks of the year for a total
of $432,000. This is a pretty optimistic figure as a dentist has a lot of
work to do besides be in the chair + they get cancellations. Most of the
surgeries I've been to have 4 or 5 staff per dentist, so 4 x $35,000 is
140k. Subtract $10k a month for running costs and paying off expensive
equipment and you're left with $172,000. And I think the initial income is a
fairly optimistic figure, if he spent 30 hours in the chair he'd be at the
surgery 50 hours per week minimum (he has to run a business also remember).
The staff figure is probably low too as these are trained dental nurses and
there's workcover, super etc. It would be fairly easy for the figure to get
closer to $100k.

On the other hand compare the full range of restaurants from your cafe on
the corner to mcdonalds (they started off as a small business too).......

Michael



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You can't make a blanket statement that the digital image can be zoomed
further than the photographic image. If the resolution is there then
both can be zoomed in. I would suggest the resolution of the
photographic image is an order of magnitude better than the digital. If
size really matters then a magnifying viewer can be used. For the other
issues mentioned, digital wins.

Cheers.

Ken

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