Searching \ for 'x-ray eraser' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: techref.massmind.org/techref/index.htm?key=ray+eraser
Search entire site for: 'x-ray eraser'.

Truncated match.
PICList Thread
'x-ray eraser'
1998\05\05@183958 by Gordon Couger

flavicon
face
>From time to time I have thought soft x-rays should erase OTP chips.
has anyone tried it. A soft x-ray source can be made from a vacuum
tube. If any one thinks it is sound I can probably set up a trial.

Gordon

1998\05\06@075208 by Leon Heller

flavicon
picon face
In message <01bd785e$874ef6c0$922cccd0@gcouger>, Gordon Couger
<spam_OUTgcougerTakeThisOuTspamRFDATA.NET> writes
>From time to time I have thought soft x-rays should erase OTP chips.
>has anyone tried it. A soft x-ray source can be made from a vacuum
>tube. If any one thinks it is sound I can probably set up a trial.
>
>Gordon

This has been discussed several times on the sci.electronics.design NG.
Some people have actually tried it, using dental X-ray sources, for
instance but I can't remember if it worked. You should be able to dig
the posts up from the archives.

Leon
--
Leon Heller: .....leonKILLspamspam@spam@lfheller.demon.co.uk http://www.lfheller.demon.co.uk
Amateur Radio Callsign G1HSM    Tel: +44 (0) 118 947 1424
See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850
DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.

1998\05\06@091821 by Gary T. Pepper

flavicon
face
At 02:46 PM 5/5/1998 -0500, Gordon Couger wrote:
>>From time to time I have thought soft x-rays should erase OTP chips.
>has anyone tried it. A soft x-ray source can be made from a vacuum
>tube. If any one thinks it is sound I can probably set up a trial.
>
>Gordon
>
>

Soft x-ray sources are ** not ** a viable method of erasing "used" OTP
devices.  The exposure of OTP devices (or any other CMOS device, for that
matter) to ionizing radiation (which includes soft x-rays) of a sufficient
level (i.e. total dose) can lead to degradation in the performance of the
device and eventually to total malfunction.

It is not advisable to play around with x-ray sources of any kind, unless
you really know what you are doing.  Besides the high voltage hazards, you
might inadvertently expose yourself to harmful levels of x-rays.  We
wouldn't want anyone permanently erasing themselves, would we?  ;-)

Take the reliable (and safe) approach.  Instead of trying to erase OTP
devices, throw out the botched ones and buy new ones.

Regards,
Gary Pepper

e-mail: gpepperspamKILLspamcapitalnet.com

Ottawa, Ontario, Canada

1998\05\06@194817 by Gordon Couger

flavicon
face
Paul B. said

>  Ah, now we're getting a bit into science fiction!  By the time you set
>up a manufacturing facility to re-construct your "vacuum tube" into an
>X-ray tube, it is hardly a backyard enterprise.
===========
Not really. There are some vacuum tubes out there that will make exrays
if you put enough voltage on them.
>
>  An X-ray tube consists of an electron gun similar to that in a CRT
>(TV, oscilloscope) *except* that it generates from five (dental, II) to
>200 times the beam current, focussed onto an oblique tungsten anode such
>that all the X-rays come out *in one direction*.  The problem with
>X-ray emission from TV tubes and the old EHT shunt regulators is that it
>comes out *all over the place*!
=============
Soft X-rays are easily contained by steal, concrete, soil water or what have
you.
>
>> If any one thinks it is sound I can probably set up a trial.
>
>  Have I made my point?
----------
Not to me. If I try it I will be sure to check it for leakeage with film
badges.
Anyone that can develop film can do that. I am a great deal more concerned
about the high voltage supply than I am the X-ray danger.

Gordon

Gordon Couger .....gcougerKILLspamspam.....rfdata.net
624 Cheyenne
Stillwater, OK 74075
405 624-2855   GMT -6:00
{Quote hidden}

1998\05\06@201103 by paulb

flavicon
face
Gordon Couger wrote:

> From time to time I have thought soft x-rays should erase OTP chips.

 The concept has merit.

> Has anyone tried it.

 I haven't yet.

> A soft x-ray source can be made from a vacuum tube.

 Ah, now we're getting a bit into science fiction!  By the time you set
up a manufacturing facility to re-construct your "vacuum tube" into an
X-ray tube, it is hardly a backyard enterprise.

 An X-ray tube consists of an electron gun similar to that in a CRT
(TV, oscilloscope) *except* that it generates from five (dental, II) to
200 times the beam current, focussed onto an oblique tungsten anode such
that all the X-rays come out *in one direction*.  The problem with
X-ray emission from TV tubes and the old EHT shunt regulators is that it
comes out *all over the place*!

> If any one thinks it is sound I can probably set up a trial.

 Have I made my point?

 Let me give you a suggestion.  If you want to try it with your
dentist, use the absolute *lowest* anode voltage to which the machine
can be set.  Whenever this discussion comes up, people start talking
about using industrial x-ray machines and the like, set up for
ridiculously high anode voltages.  It seems not to be intuitive to them
that "hard" X-rays which simply travel straight through the plastic
package, silicon die, object holding the chip, the table, the floor and
just keep on going have *no* effect erasing a chip!

 Cheers,
       Paul B.

1998\05\07@014955 by Mike Keitz

picon face
On Thu, 7 May 1998 07:54:21 +1000 "Paul B. Webster VK2BZC"
<EraseMEpaulbspam_OUTspamTakeThisOuTmidcoast.com.au> writes:
>Gordon Couger wrote:
>
>> From time to time I have thought soft x-rays should erase OTP chips.
>
>  The concept has merit.
>
>> Has anyone tried it.

It erases the chips alright, but it also ruins them.

X-ray generating devices are not new, and neither are plastic OTP EPROM
chips.  Many people have tried.  Some have claimed success.  They have
only erased their chip once and it is likely not fully up to
specifications because of radiation damage.  If it really did work, there
would be little reason to sell window EPROM chips.  Instead, small x-ray
generators would be used instead of UV lamps.

>> A soft x-ray source can be made from a vacuum tube.

>  An X-ray tube consists of an electron gun similar to that in a CRT
>(TV, oscilloscope) *except* that it generates from five (dental, II)
>to
>200 times the beam current, focussed onto an oblique tungsten anode
>such
>that all the X-rays come out *in one direction*.

Such a complicated tube is used for X-ray photography because in order to
produce a good image, the X-rays need to effectively come from a "point
source".  An X-ray picture is essentially a shadow of the more
inpenetrable parts of the object being X-rayed, cast onto the film.  If
the X-rays came from a large diffuse area, the shadow would be blurred.
So the tube is built to focus the electrons to one spot on the anode. The
anode needs to be made of tungsten or similar material because very
concentrated heat (as well as a few X-rays) is generated by electrons
striking the focus point.  I remember something about tungsten also
working better than most metals at converting the energy from colliding
electrons into X-rays.  Obviously, setting the target at an angle makes
it easier for the X-rays to get out of the tube since they don't have to
pass through the target first.

Ordinary tubes with thin metal anodes should allow some X-rays to pass to
the outside of the anode, then out through the glass.  The tube's anode
will likely overheat before producing any significant amount of
X-radiation.  I have seen high-voltage TV diode tubes with lead/rubber
shields on the outside and dire warnings about not messing with the
shield.  I suspect the level of X-rays produced from these tubes even
without the shields was miniscule.  But the government was concerned
about having any measurable source of X-rays so close to millions of
people for such a long time.


The problem with
>X-ray emission from TV tubes and the old EHT shunt regulators is that
>it
>comes out *all over the place*!

This is not a problem, as long as the extra X-rays are kept from
irradiating anyone.  Of course using a concentrated powerful source would
reduce the damage/erasure time.



_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]

1998\05\07@195437 by paulb

flavicon
face
Gordon Couger wrote:

> There are some vacuum tubes out there that will make X-rays if you put
> enough voltage on them.

 And you can erase windowed PICs by sitting them in the sunlight too.

 I think you still missed my implication.  X-ray tubes are designed to
make X-rays in useful quantities, with reasonable efficiency, and to
deliver them to the desired target.  Your vacuum rectifiers or triodes
will by all means generate X-rays, but are likely to perform none of
these functions within three or four orders of magnitude.

> Soft X-rays are easily contained by steel, concrete, soil water or
> what have you.

 Indeed they are, but again, design of commercial equipment is based on
making as many of the X-rays come out of the business end, and as few in
the other direction as possible.

> Not to me. If I try it I will be sure to check it for leakeage with
> film badges.

 You have access to these?

> Anyone that can develop film can do that.

 I suspect you *don't* have access to film badges then.  Are you under
the impression that they contain simply film?  Do you know what an X-ray
film "plate" is?

> I am a great deal more concerned about the high voltage supply than I
> am the X-ray danger.

 Quite so, if you are using home-built equipment, it *would* be by far
the greater danger.

 I still say that you would be far better to try it out with the help
of a friendly dentist.

 Cheers,
       Paul B.

1998\05\07@201821 by Gordon Couger

flavicon
face
.
>
>  I think you still missed my implication.  X-ray tubes are designed to
>make X-rays in useful quantities, with reasonable efficiency, and to
>deliver them to the desired target.  Your vacuum rectifiers or triodes
>will by all means generate X-rays, but are likely to perform none of
>these functions within three or four orders of magnitude.
========
I don't expect them to be fast.
>
>> Soft X-rays are easily contained by steel, concrete, soil water or
>> what have you.
>
>  Indeed they are, but again, design of commercial equipment is based on
>making as many of the X-rays come out of the business end, and as few in
>the other direction as possible.
=======
A steel pipe with a window in a hot region will work. See the Bell jar mail
list.
>
>> Not to me. If I try it I will be sure to check it for leakeage with
>> film badges.
>
>  You have access to these?
========
Last I looked free style had X-ray film. All film is to some degree
sensitive
to soft X-rays.
>
>> Anyone that can develop film can do that.
>
>  I suspect you *don't* have access to film badges then.  Are you under
>the impression that they contain simply film?  Do you know what an X-ray
>film "plate" is?
---------
I do have accesst to both through the college.
>
>> I am a great deal more concerned about the high voltage supply than I
>> am the X-ray danger.
>
>  Quite so, if you are using home-built equipment, it *would* be by far
>the greater danger.
============
I have been playing with high voltabe supplys for 40 years and I am still
here to tell the tail. Safety is a learned skill not a set of
incoprehemsible
rules. It is not societys job to protect me from my self. It is socites job
to protect my neighbors from me.

We have come to the point that any risk is precived as unaccepible. If the
same standards of risk were applied to automibles as pesticides there
would not be a car on the road today.

Grodon
>
>  I still say that you would be far better to try it out with the help
>of a friendly dentist.
---------------
I would use the vet med college.
>
>  Cheers,
> Paul B.
>
>

1998\05\08@035035 by Maris

picon face
Paul B. Webster wrote:
>  I think you still missed my implication.  X-ray tubes are designed to
>make X-rays in useful quantities, with reasonable efficiency, and to
>deliver them to the desired target.  Your vacuum rectifiers or triodes
>will by all means generate X-rays, but are likely to perform none of
>these functions within three or four orders of magnitude.


       The Amateur Scientist column in Scientific American had plans for making
an X-ray machine many years ago. It was made from an old "01" vacuum tube,
used only for its vacuum. All the pins of the tube were tied together and
connected to a high voltage power supply. At the top of the tube (on the
outside) was a cap made of aluminum foil, connected to the other terminal
of the high voltage supply. This made a capacitive connection to the
magnesium "getter" inside the top of the tube. (This probably wouldn't work
too well if there was no "getter",  a thin film of magnesium deposited
inside the tube to improve the vacuum). The electrons were accelerated from
the metal structures in the tube toward the "getter" and produced X-rays
upon striking the magnesium.
       The power supply was a vibrator-type spark coil (like a model-T type)
driving a small Tesla coil producing about 75KV of high frequency AC. (I
think Edmund Scientific sells a small 75KV Tesla coil which could also be
used). This produced dangerous quantities of X-rays and had to be
completely shielded with several layers of lead sheet. There was a small
opening in the shielding covered by a lead shutter which let the X-rays out
when opened. The article included some photographs of the X-rays
penetrating various objects, including some thin steel thickness gages.
       This would have no problem in penetrating (and probably destroying)
various PIC chips.
                               *****

       To anyone trying this: X-ray radiation is extremely dangerous. Proper
shielding is a must; this type of tube would send X-rays in all directions.
Find and read the original article in your library. Know what you are
doing!!

1998\05\08@053859 by Andres j Ogayar

flavicon
face
Hi, list.

   Here in our plant -I do work for an automitive microelectronics firm-
there is an X-RAY machine which makes tests of soldering dots after the
infrared oven on SMD boards.

   These boards do carry on an either an OTP or a masked Motorola
microcontroller, and many other chips. Apologize, but I can not provide more
details, because of the legal stuff.

   Boards can be exposed to this X-RAY during hours, and there is no harm
to the chips.

   But, if the X-RAY is enough, the chips are fried all of them. There is
an OTP erasing so good that you can never use it... nor the rest of the
chip.

   OTP are done just for that purpose: One Time Programming, and the
kitchen tricks are only that.

   Regards,

   Andres j. Ogayar

1998\05\11@203040 by paulb

flavicon
face
Hello Gordon.

> I don't expect them to be fast.

 Just as well.  I have looked at the website specified
( http://www.mathematik.uni-marburg.de/~kronjaeg/hv/index.html ) and he
refers to exposures in the order of some hours.  He notes the limits of
heating of the valves he uses.  I think this validates my reference to
"orders of magnitude".  It is probably much safer for me to use a
commercially purpose-built X-ray machine for a minute or two (at low
power) whilst standing behind a wall or two than to have a
poorly-designed one run for hours or days.

 In comparing film exposure to chip erasure, consider the exposure time
for chip erasure (minutes) to UV against how long (fraction of second)
it would take to blacken a film.  More orders of magnitude!

> Last I looked free style had X-ray film.  All film is to some degree
> sensitive to soft X-rays.

 The secret is: Film "badges" and X-ray plates contain fluorescent
screens which intercept the X-rays, converting them to light which
exposes the film.  This increases film sensitivity by another order of
magnitude, and is difficult to home-build.

> I have been playing with high voltage supplys for 40 years and I am
> still here to tell the tale.  Safety is a learned skill not a set of
> incoprehemsible rules.

 I wouldn't put too much emphasis on "learned", at least not in the
practical sense!

> It is not societys job to protect me from my self.  It is societys job
> to protect my neighbors from me.

 You are not "politically correct"!  In my profession, the courts are
telling us now it is *our* responsibility to protect people from
themselves!

> We have come to the point that any risk is percieved as unacceptable.
> If the same standards of risk were applied to automobiles as
> pesticides there would not be a car on the road today.

 Ahh, but cars are "big business"; the rules are different.

 It is funny, isn't it?

> I would use the vet med college.

 It's a dog of an idea!

 Cheers,
       Paul B.

1998\05\11@235856 by Gordon Couger

flavicon
face
>
>> Last I looked free style had X-ray film.  All film is to some degree
>> sensitive to soft X-rays.
>
>  The secret is: Film "badges" and X-ray plates contain fluorescent
>screens which intercept the X-rays, converting them to light which
>exposes the film.  This increases film sensitivity by another order of
>magnitude, and is difficult to home-build.
------------
The flouoresent layer is for high energy stuff. If I remember my physics
right the higher the energy of the radiation the less likelyhood of it
exposing
the film. Soft X-rays don't need help.

>> I have been playing with high voltage supplys for 40 years and I am
>> still here to tell the tale.  Safety is a learned skill not a set of
>> incoprehemsible rules.
>
>  I wouldn't put too much emphasis on "learned", at least not in the
>practical sense!
---------
Would you expound on that some. I was taught safety from before I can
remember. I was tuned loose on my own with a shot gun when I was 12
and a rifle when I was 13. I stand by safety being a personal responsiblity.
I have refused to work on machines I felt weren't safe. Manufactures
software included should make devices as safe as they can. But there is
no way to make safe danimite.

>> It is not societys job to protect me from my self.  It is societys job
>> to protect my neighbors from me.
>
>  You are not "politically correct"!  In my profession, the courts are
>telling us now it is *our* responsibility to protect people from
>themselves!
---------
Damn right I am not politicly correct.
>
Gordon

Gordon Couger gcougerspamspam_OUTrfdata.net
624 Cheyenne
Stillwater, OK 74075
405 624-2855   GMT -6:00

1998\05\12@073827 by paulb

flavicon
face
Hello Gordon.

> The fluoresent layer is for high energy stuff.  If I remember my
> physics right the higher the energy of the radiation the less
> likelihood of it exposing the film.

 In a sense, which is why I have dwelt on the need to use only the
"Softest" X-rays if one was to try and erase a OTP chip.

> Soft X-rays don't need help.

 *Extremely* soft ones may not need *much*, but nearly all will benefit
by a factor of more than ten (an order of magnitude) from a ZnS plate
which catches the (most) X-rays the (thin!) emulsion won't.

> Would you expound on that some.

 Yes, I meant learning from experience, i.e., putting oneself in risky
situations.

> I was taught safety from before I can remember. I was tuned loose on
> my own with a shot gun when I was 12 and a rifle when I was 13.

 Hey, that's a hot topic currently, isn't it?

> But there is no way to make safe dynamite.

 My father quotes the explosives instructor hitting a (new) stick of
dynamite with a hammer to demonstrate how safe it was.  Old stock is a
different matter.  Perhaps you've had some bad experiences.

> Damn right I am not politicly correct.

 One doesn't expect to find "Politically correct" people on this list
does one?  I have said before that few if any list-members would have an
IQ below 105.

 Cheers,
       Paul B.

More... (looser matching)
- Last day of these posts
- In 1998 , 1999 only
- Today
- New search...