In preparation for cutting my Apple IIe motherboard in half I decided
it would help to have an x-ray of the board.  This way it will be easy
to determine the most efficient cut line.

I included an X-Ray of a Disk II card just for fun.

The X-Rays are at 300dpi.  I'm not an X-Ray tech so my calibration was
a little off.  Our resident X-ray guy is gone today.  I'm not sure he
would be interested in an Apple IIe motherboard any way.  ; )  Some
areas are dark.  By adjusting "Levels" in photoshop you can bring them
out.

The motherboard received a dose rate of 17.84 R/min for the scans and
calibration.  About 27 minutes (for 3 scans and a calibration).  This
would have been a dose of 482 Rad.

The Disk II card received the same dose rate, but it was in the vault
for the whole time the motherboard was in there.  It received radiation
for a total of about 32 minutes.  571 Rad.

To put it in perspective, if a group of people were exposed to that
dose 50-90% would die after 30 days.  (90% without intensive medical
care).  Primary cause of death is internal bleeding and infections.
Females become sterile.

Motherboard:
http://www.stockly.com/images2/061228-Apple_II_80kv6ma35ms36SFD-Cut%20Edges.jpg

Disk II:
http://www.stockly.com/images2/061228-Disk_II_80kv6ma35ms36SFD-Cut%20Edges.jpg

Any comments?

Grant

"Grant Stockly" <grant@stockly.com> wrote in message news:1167347657.200472.40280@79g2000cws.googlegroups.com...
: In preparation for cutting my Apple IIe motherboard
: in half I decided it would help to have an x-ray of
: the board.  This way it will be easy to determine the
: most efficient cut line.
:
: I included an X-Ray of a Disk II card just for fun.
:
: The X-Rays are at 300dpi.  I'm not an X-Ray tech so
: my calibration was a little off.  Our resident X-ray
: guy is gone today. I'm not sure he would be interested
: in an Apple IIe motherboard any way.  ; )  Some areas
: are dark.  By adjusting "Levels" in photoshop you can
: bring them out.
:
: The motherboard received a dose rate of 17.84 R/min
: for the scans and calibration.  About 27 minutes (for
: 3 scans and a calibration).  This would have been a
: dose of 482 Rad.
:
: The Disk II card received the same dose rate, but it
: was in the vault for the whole time the motherboard
: was in there. It received radiation for a total of
: about 32 minutes.  571 Rad.
:
: To put it in perspective, if a group of people were
: exposed to that dose 50-90% would die after 30 days.
: (90% without intensive medical care).  Primary cause
: of death is internal bleeding and infections.
: Females become sterile.
:
: Motherboard:
: http://www.stockly.com/images2/061228-Apple_II_80kv6ma35ms36SFD-Cut%20Edges.jpg
:
: Disk II:
: http://www.stockly.com/images2/061228-Disk_II_80kv6ma35ms36SFD-Cut%20Edges.jpg
:
: Any comments?
:
: Grant

This is cool. Too bad they weren't bare boards
when they were run through.

As far as cutting the board straight through,
I don't see it happening. You'll need to route
it back and forth a couple places, but, there
is one area that you could get away with it.
Either just in front of the slot row, or just
behind the Chargen/Ram row.

William Garber
Email Address - willy46pa@garberstreet.com
Alt. Email - willy46pa@comcast.net
Web address - http://www.garberstreet.com

Grant Stockly ha escrito:
>
> Any comments?

Yes.
In Spain, the 28th of December is (*) like the 1st of April there.

So that's not a joke ?

Regards,
Jorge Chamorro.

(*)  "D=EDa de los Santos Inocentes"

> This is cool. Too bad they weren't bare boards
> when they were run through.
>
> As far as cutting the board straight through,
> I don't see it happening. You'll need to route
> it back and forth a couple places, but, there
> is one area that you could get away with it.
> Either just in front of the slot row, or just
> behind the Chargen/Ram row.

The only place I can get enough room is right behind the slots.

This board, worst case, only got 500-600 rad.

Rule of thumb is electronics can get about 2,000 rad and not be hurt.
6kRad and Flash/Eeprom is damaged.  Parts get very hot and can cook
themselvs (in operation, not from X-rays).

With a current limiting power supply we were able to get a
microcontroller to last 13kRad.  Without a CC power supply it would
have blown almost instantly.

So the Apple IIe should still be good.  ; )

"Grant Stockly" <grant@stockly.com> wrote in message news:1167350220.391120.60190@n51g2000cwc.googlegroups.com...
: > This is cool. Too bad they weren't bare boards
: > when they were run through.
: >
: > As far as cutting the board straight through,
: > I don't see it happening. You'll need to route
: > it back and forth a couple places, but, there
: > is one area that you could get away with it.
: > Either just in front of the slot row, or just
: > behind the Chargen/Ram row.
:
: The only place I can get enough room is right
: behind the slots.

If that makes the board short enough, go for it.

: This board, worst case, only got 500-600 rad.
:
: Rule of thumb is electronics can get about 2,000
: rad and not be hurt. 6kRad and Flash/Eeprom is
: damaged.  Parts get very hot and can cook themselves
: (in operation, not from X-rays).
:
: With a current limiting power supply we were able
: to get a microcontroller to last 13kRad.  Without
: a CC power supply it would have blown almost instantly.
:
: So the Apple IIe should still be good.  ; )


You've probably misread my implication. What I meant
was, so you can see ALL of the traces on both sides
of the board.  :o)))

William Garber
Email Address - willy46pa@garberstreet.com
Alt. Email - willy46pa@comcast.net
Web address - http://www.garberstreet.com

> You've probably misread my implication. What I meant
> was, so you can see ALL of the traces on both sides
> of the board.  :o)))

That was just a general comment

By adjusting the "levels" you can see through the dies.  I adjusted the
image levels to show the entire dynamic range of the x-ray.  The
original image was 12bit greyscale.

I could adjust them to show the traces by sacrificing other parts of
the image.

In article <1167347657.200472.40280@79g2000cws.googlegroups.com>,
 "Grant Stockly" <grant@stockly.com> wrote:

> In preparation for cutting my Apple IIe motherboard in half I decided
> it would help to have an x-ray of the board.  This way it will be easy
> to determine the most efficient cut line.
> 
> I included an X-Ray of a Disk II card just for fun.
> 
> The X-Rays are at 300dpi.  I'm not an X-Ray tech so my calibration was
> a little off.  Our resident X-ray guy is gone today.  I'm not sure he
> would be interested in an Apple IIe motherboard any way.  ; )  Some
> areas are dark.  By adjusting "Levels" in photoshop you can bring them
> out.
> 
> The motherboard received a dose rate of 17.84 R/min for the scans and
> calibration.  About 27 minutes (for 3 scans and a calibration).  This
> would have been a dose of 482 Rad.
> 
> The Disk II card received the same dose rate, but it was in the vault
> for the whole time the motherboard was in there.  It received radiation
> for a total of about 32 minutes.  571 Rad.
> 
> To put it in perspective, if a group of people were exposed to that
> dose 50-90% would die after 30 days.  (90% without intensive medical
> care).  Primary cause of death is internal bleeding and infections.
> Females become sterile.
> 
> Motherboard:
> http://www.stockly.com/images2/061228-Apple_II_80kv6ma35ms36SFD-Cut%20Edges.jp
> g
> 
> Disk II:
> http://www.stockly.com/images2/061228-Disk_II_80kv6ma35ms36SFD-Cut%20Edges.jpg
> 
> Any comments?
> 
> Grant
> 

Neat to see...

Not so much a comment as a question: Does it still boot? I'd expect some 
*SERIOUS* bit-rot in the ROMS (Particularly the PROMs on the disk 
controller), and even worse trouble in the RAM chips.

-- 
Don Bruder - dakidd@sonic.net - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info

> Neat to see...
>
> Not so much a comment as a question: Does it still boot? I'd expect some
> *SERIOUS* bit-rot in the ROMS (Particularly the PROMs on the disk
> controller), and even worse trouble in the RAM chips.

I don't think anything will happen.  I've x-rayed a ton of junk at MUCH
higher dose rates and there hasn't been any damage.  My coworker's cell
phone has seen a lot of time.  ; )

The Apple IIe shouldn't have any bad signs for at least 2,000 rad.
PROM takes a lot more radiation to erase than EPROM.  Even EPROM is
safe at the radiation dose I gave it.

Hi Grant,

> Any comments?

Question for you ... what does a 4 layer board look like when it has
been xray'd? Is it possible to see all 4 layers perhaps in different
gray scales?

Glenn

Grant Stockly schrieb:
>
> With a current limiting power supply we were able to get a
> microcontroller to last 13kRad.  Without a CC power supply it would
> have blown almost instantly.

What's your job, exactly? MilSpec? ;-)

bye
Marcus

On Dec 28, 10:20 pm, rg.jo...@rogers.com wrote:
> Hi Grant,
>
> > Any comments?Question for you ... what does a 4 layer board look like when it has
> been xray'd? Is it possible to see all 4 layers perhaps in different
> gray scales?
>
> Glenn

  Both of those cards are 4 layer.  Traces on top and bottom, and the
power and ground on separate layers in the middle.

Raymond

> > > Any comments?Question for you ... what does a 4 layer board look like when it has
> > been xray'd? Is it possible to see all 4 layers perhaps in different
> > gray scales?
> >
> > Glenn
>
>   Both of those cards are 4 layer.  Traces on top and bottom, and the
> power and ground on separate layers in the middle.
>
> Raymond

On the boards I posted x-rays of?  Those are not 4 layer.  They only
have a top and bottom copper layers.

>   Both of those cards are 4 layer.  Traces on top and bottom, and the
> power and ground on separate layers in the middle.

Here are two shots of a 512k motherboard.  You can see the difference.
This is what a 4 layer board looks like.  You can see the holes in the
middle layers where the through hole devices go through.

http://media.diywelder.com/images3/090605-512kRAM.jpg

http://media.diywelder.com/images3/090605-512kProcessor.jpg

Grant Stockly wrote:
> > > > Any comments?Question for you ... what does a 4 layer board look like when it has
> > > been xray'd? Is it possible to see all 4 layers perhaps in different
> > > gray scales?
> > >
> > > Glenn
> >
> >   Both of those cards are 4 layer.  Traces on top and bottom, and the
> > power and ground on separate layers in the middle.
> >
> > Raymond
>
> On the boards I posted x-rays of?  Those are not 4 layer.  They only
> have a top and bottom copper layers.

  That's right.  I was thinking of the Mac 128K board when I said that.
 They even had a little 1-2-3-4 layout so you could see the layers.
The Apple /// Plus logic was a 4 layer board as well.  Had to do with
eliminating all those capacitor strips on the Apple ///.  

Raymond

Grant Stockly schrieb:
>
> Here are two shots of a 512k motherboard.  You can see the difference.
> This is what a 4 layer board looks like.  You can see the holes in the
> middle layers where the through hole devices go through.
>
> http://media.diywelder.com/images3/090605-512kRAM.jpg
>
> http://media.diywelder.com/images3/090605-512kProcessor.jpg

Those RAMs above the 68k have funny "paths" inside.

Very interesting to see!
If you feel the urge to xray/post some more - please do it!  :o)

bye
Marcus

In article <1167369322.333980.17360@n51g2000cwc.googlegroups.com>,
 heuser.marcus@freenet.de wrote:

> Grant Stockly schrieb:
> >
> > With a current limiting power supply we were able to get a
> > microcontroller to last 13kRad.  Without a CC power supply it would
> > have blown almost instantly.
> 
> What's your job, exactly? MilSpec? ;-)

I would guess either satellites or some sort of spacecraft.  This is the 
kind of trivia you learn when you build space probes to go to Jupiter.

heuser.marcus@freenet.de wrote:
> Grant Stockly schrieb:
> 
>>Here are two shots of a 512k motherboard.  You can see the difference.
>>This is what a 4 layer board looks like.  You can see the holes in the
>>middle layers where the through hole devices go through.
>>
>>http://media.diywelder.com/images3/090605-512kRAM.jpg
>>
>>http://media.diywelder.com/images3/090605-512kProcessor.jpg
> 
> 
> Those RAMs above the 68k have funny "paths" inside.
> 
> Very interesting to see!

It looks like skew minimizing routing...

> If you feel the urge to xray/post some more - please do it!  :o)

I agree--I've already posted the //e X-ray on my wall.  ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

> > Those RAMs above the 68k have funny "paths" inside.
> >
> > Very interesting to see!
> It looks like skew minimizing routing...


I think he was talking about the inside of the ICs???

> > If you feel the urge to xray/post some more - please do it!  :o)
>
> I agree--I've already posted the //e X-ray on my wall.  ;-)

I think the next step is to x-ray a full Apple IIe with cards and a
monitor.  : )

That might be too much to tell what is going on.  So we could do the
Apple IIe and Monitor separately.

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Would the late Model //e be easier to cut? Ie loer chip count less
circuit traces to cut?

--=20
V/R
Mark Frischknecht

si vis pacem, para bellum
http://www.appleiiguy.net
Apple ][ Forever!


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Mark Frischknecht wrote:
> Would the late Model //e be easier to cut? Ie loer chip count less
> circuit traces to cut?

Do you know where I can get a picture of this motherboard?

Grant

Grant Stockly wrote:
> Do you know where I can get a picture of this motherboard?

Google Images "platinum iie" returned the following on the 2nd page:

http://sbm.ordinotheque.free.fr/apple/a2ep/a2ep_mb.jpg

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Grant Stockly wrote:
> Mark Frischknecht wrote:
>> Would the late Model //e be easier to cut? Ie loer chip count less
>> circuit traces to cut?
>=20
> Do you know where I can get a picture of this motherboard?
>=20
> Grant
>=20
Here is a scan of the bottom of my IIe Enhanced board
http://www.appleiiguy.net/images/IIEenhancedbottom.jpg

--=20
V/R
Mark Frischknecht

si vis pacem, para bellum
http://www.appleiiguy.net
Apple ][ Forever!


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> Here is a scan of the bottom of my IIe Enhanced board
> http://www.appleiiguy.net/images/IIEenhancedbottom.jpg

That looks like my motherboard.

Do you guys want a composite shot of it?

I'm going to x-ray a disk II drive next.  : )

Grant Stockly wrote:
>>>Those RAMs above the 68k have funny "paths" inside.
>>>
>>>Very interesting to see!
>>
>>It looks like skew minimizing routing...
> 
> 
> 
> I think he was talking about the inside of the ICs???

Yes, inside the packages--that's where I've seen very serpentine
paths used to minimize skew on address and data lines.

>>>If you feel the urge to xray/post some more - please do it!  :o)
>>
>>I agree--I've already posted the //e X-ray on my wall.  ;-)
> 
> 
> I think the next step is to x-ray a full Apple IIe with cards and a
> monitor.  : )
> 
> That might be too much to tell what is going on.  So we could do the
> Apple IIe and Monitor separately.

I must admit to feeling some revival of the desire to build my
own X-ray machine.  But I thought that modern CCDs had drastically
reduced the "dosage" required to get an exposure.  The several-
hundred-RAD territory sounds a bit out of my range.  ;-)

Then there's the issue of X-ray wavelength, or energy.  Apparently
80kV does an excellent job of penetrating circuit boards and thin
copper, but 80kV is not a weekend project.

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

> I must admit to feeling some revival of the desire to build my
> own X-ray machine.  But I thought that modern CCDs had drastically
> reduced the "dosage" required to get an exposure.  The several-
> hundred-RAD territory sounds a bit out of my range.  ;-)

It was several hundred rad for 16 or so full exposures.  The exposure
required depends on the pixel size.  That was quite a high resolution
x-ray.  ;)

That said, 80kv 6ma is hardly anything.  The tube I was using goes up
to 160kv 20ma, and it isn't our biggest tube.  We have a tube that goes
up to 420kv and 10ma.  THAT is a high dose...

I imagine that an old AM radio tube could make some crude x-rays...  Or
you could buy an x-ray tube off of ebay.  : )

Grant Stockly wrote:
> I'm going to x-ray a disk II drive next.  : )

If you have one, I would love to see an x-ray of a FingerPrint GS card.
I have a few of these and would like to see how they work (maybe adapt
one to do something else). They are effectively a 65c02 co-processor
card.

Grant Stockly wrote:
>>I must admit to feeling some revival of the desire to build my
>>own X-ray machine.  But I thought that modern CCDs had drastically
>>reduced the "dosage" required to get an exposure.  The several-
>>hundred-RAD territory sounds a bit out of my range.  ;-)
> 
> 
> It was several hundred rad for 16 or so full exposures.  The exposure
> required depends on the pixel size.  That was quite a high resolution
> x-ray.  ;)
> 
> That said, 80kv 6ma is hardly anything.  The tube I was using goes up
> to 160kv 20ma, and it isn't our biggest tube.  We have a tube that goes
> up to 420kv and 10ma.  THAT is a high dose...
> 
> I imagine that an old AM radio tube could make some crude x-rays...  Or
> you could buy an x-ray tube off of ebay.  : )

Those power levels sound much more doable, but 480 Watts is still
quite a supply!  What type of power supply does it use?

I used to have a couple of big X-ray tubes, one about 18 inches long
with a central bulb about 6 inches in diameter, and one about 24 inches
long with a cylindrical central enlargement and window about 8 inches
in diameter.  Both envelopes had the characteristic darkening from
receiving a large radiation dose.

When I was in high school, I imagined operating them with an induction
coil, but the highest voltage DC supply I ever made was about 2800v
(at 15mA), and it was a linear supply.  A flyback supply for 30kV at
about 1mA seemed practical, but I never aspired to higher powered vacuum
tube circuits.  ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

Michael J. Mahon wrote:
>> copper, but 80kV is not a weekend project.
> 


how about a NeonSign Transformer?

Rich

aiiadict@gmail.com wrote:
> Michael J. Mahon wrote:
> 
>>>copper, but 80kV is not a weekend project.
>>
> 
> 
> how about a NeonSign Transformer?

They are typically in the 8kV to 15kV range, at 10mA or so.

Using a diode-capacitor voltage multiplier would require
6x or so to get near 8okV and the available current would
be less than 1mA.

Ideally, the supply would be regulated, and I'd think that
a high-frequency switcher would be the best approach.  The
HV diode string would be an issue.  Using a multiplier chain
approach would be possible, but they get pretty inefficient
beyond 2x-3x, and at these power levels, efficiency is important.

Using the horizontal output section of a *large* CRT TV would
be an interesting place to start, but multiplication would
still be needed, and the available power is only 10W-20W.

High voltage at medium power levels (like 500W) is still
an "interesting" implementation.

Grant, I deduce that the exposures were about 2 minutes--
is that right?  If so, it would be hard to reduce the power
level by increasing exposure time, because of CCD noise.

BTW, is this a direct line-scan CCD image, or is it a full-
area image?  (I assume no "lenses" are involved.)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

> Those power levels sound much more doable, but 480 Watts is still
> quite a supply!  What type of power supply does it use?

Some units use a transformer to go from 80v to 800v and then use diode
doublers to get it to 80kv.

Along with each doubler step there is often a feedback resistor.  On a
450kv system you will have a voltage dividor with a resistance of
around 1.5G.  : )

> When I was in high school, I imagined operating them with an induction
> coil, but the highest voltage DC supply I ever made was about 2800v
> (at 15mA), and it was a linear supply.  A flyback supply for 30kV at
> about 1mA seemed practical, but I never aspired to higher powered vacuum
> tube circuits.  ;-)

Even a low power x-ray tube can be very dangerous.  If you do anything
like this you should take a radiation safety course, get a book, survey
meter (and calibrate it).

X-rays are invisible death rays if you don't take proper safety
measures.

> Using a diode-capacitor voltage multiplier would require
> 6x or so to get near 8okV and the available current would
> be less than 1mA.

70-80kv at .3ma will do a decent job too.

> High voltage at medium power levels (like 500W) is still
> an "interesting" implementation.

or 4.2kw  : )

> Grant, I deduce that the exposures were about 2 minutes--
> is that right?  If so, it would be hard to reduce the power
> level by increasing exposure time, because of CCD noise.

The exposure of each line was 30ms.  I was only operating the tube at
1/4 power.  If I cranked it up to 80kv 20ma I could have done the shot
much faster.

> BTW, is this a direct line-scan CCD image, or is it a full-
> area image?  (I assume no "lenses" are involved.)

Its a line.

If you ever tried something like this your best bet is to submerge the
tube, transformer, and doublers in oil and seal/vacuum all the air from
the bundle.  Otherwise you're going to have arcing all over the place.

There are places that will sell you just a tube.  A little tiny one the
size of a D cell battery that work pretty good.  (30-40w)

Grant Stockly wrote:
>>Those power levels sound much more doable, but 480 Watts is still
>>quite a supply!  What type of power supply does it use?
> 
> 
> Some units use a transformer to go from 80v to 800v and then use diode
> doublers to get it to 80kv.

After 100 stages of multiplication, getting 6-10mA would require some
pretty good sized capacitors at 60Hz, so I'm guessing that this is a
high-frequency switching supply.

> Along with each doubler step there is often a feedback resistor.  On a
> 450kv system you will have a voltage dividor with a resistance of
> around 1.5G.  : )
> 
> 
>>When I was in high school, I imagined operating them with an induction
>>coil, but the highest voltage DC supply I ever made was about 2800v
>>(at 15mA), and it was a linear supply.  A flyback supply for 30kV at
>>about 1mA seemed practical, but I never aspired to higher powered vacuum
>>tube circuits.  ;-)
> 
> 
> Even a low power x-ray tube can be very dangerous.  If you do anything
> like this you should take a radiation safety course, get a book, survey
> meter (and calibrate it).
> 
> X-rays are invisible death rays if you don't take proper safety
> measures.

I understand--physics was my subject even then.  (I have also always
been a lead collector--I'm guessing I have a couple hundred pounds,
most of it from thrown wheel weights I found while riding my
bicycle.  ;-)

I still remember standing on the foot X-ray in the Thom McCann
shoe store, holding the button down and wiggling my toes while
peering at the fluoroscope.  ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

Grant Stockly wrote:
>>Using a diode-capacitor voltage multiplier would require
>>6x or so to get near 8okV and the available current would
>>be less than 1mA.
> 
> 
> 70-80kv at .3ma will do a decent job too.
> 
> 
>>High voltage at medium power levels (like 500W) is still
>>an "interesting" implementation.
> 
> 
> or 4.2kw  : )
> 
> 
>>Grant, I deduce that the exposures were about 2 minutes--
>>is that right?  If so, it would be hard to reduce the power
>>level by increasing exposure time, because of CCD noise.
> 
> 
> The exposure of each line was 30ms.  I was only operating the tube at
> 1/4 power.  If I cranked it up to 80kv 20ma I could have done the shot
> much faster.
> 
> 
>>BTW, is this a direct line-scan CCD image, or is it a full-
>>area image?  (I assume no "lenses" are involved.)
> 
> 
> Its a line.
> 
> If you ever tried something like this your best bet is to submerge the
> tube, transformer, and doublers in oil and seal/vacuum all the air from
> the bundle.  Otherwise you're going to have arcing all over the place.
> 
> There are places that will sell you just a tube.  A little tiny one the
> size of a D cell battery that work pretty good.  (30-40w)

It might be even easier to find an old dental X-ray...

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

> It might be even easier to find an old dental X-ray...

They only make x-rays for a second or two.  And usually its a bunch of
pulses, not a constant potential source.

I have a manual with schematics for a COTS system I can send you.

> After 100 stages of multiplication, getting 6-10mA would require some
> pretty good sized capacitors at 60Hz, so I'm guessing that this is a
> high-frequency switching supply.

Some new ones are.  Old units are just huge and heavy.  Lifting eyes on
the top.  :)

But If you double your double and so on you'll only need 10 stages.
Right?

> I understand--physics was my subject even then.  (I have also always
> been a lead collector--I'm guessing I have a couple hundred pounds,
> most of it from thrown wheel weights I found while riding my
> bicycle.  ;-)

Our last cabinet for 450kv 10ma weighed in at around 8,000lbs.  : )

Michael J. Mahon wrote:

> I still remember standing on the foot X-ray in the Thom McCann
> shoe store, holding the button down and wiggling my toes while
> peering at the fluoroscope.  ;-)

That was definitely a late 40's, early 50's thing for me.

I guess you saw it somewhat later...

Grant Stockly wrote:
>>After 100 stages of multiplication, getting 6-10mA would require some
>>pretty good sized capacitors at 60Hz, so I'm guessing that this is a
>>high-frequency switching supply.
> 
> 
> Some new ones are.  Old units are just huge and heavy.  Lifting eyes on
> the top.  :)
> 
> But If you double your double and so on you'll only need 10 stages.
> Right?

Typical voltage multipliers don't work that way--they have a stage
for each multiple of the input voltage.  The diagrams you sent me
are just such multipliers of the Cockroft-Walton type.

It has ten stages in five modules, for a multiplier of 10x (minus
losses).

The transformer that drives it steps up the input 25kHz squarewave
from, say, 80 volts to 8000 volts, then the multiplier takes it
to 80kV.

>>I understand--physics was my subject even then.  (I have also always
>>been a lead collector--I'm guessing I have a couple hundred pounds,
>>most of it from thrown wheel weights I found while riding my
>>bicycle.  ;-)
> 
> 
> Our last cabinet for 450kv 10ma weighed in at around 8,000lbs.  : )

If you want to shield a large volume from high energy photons, it takes
a lot of mass.

Radar has just advised me that if I take a sharp turn right *here* I
can graze the edge of the group's topic.  ;-)

In addition to soft errors ("single event upsets") caused by alpha
particles (of past DRAM fame), cosmic ray showers also produce enough
ionizing radiation to cause DRAMs or even dense SRAMs and registers
to experience bit-flips.

The atmosphere is our security blanket in most cases on the planet, and
error-correcting codes are the backup plan.  The total sensitive volume
of an Apple II, combined with its rather huge transistors, make it quite
safe most of the time without any correction--or even detection!  But a
large server with a thousand times as much "active volume" and much
smaller (more modern) transistors is a lot more susceptible, and relies
more on error-detecting-and-correcting codes to keep its DRAM stable.

A few years ago, a server in the Denver area began to experience error
rates just above the threshold of what the error correction could handle
without special effort--the rate of uncorrected errors was many times
as high as the same system nearer sea level, because it was above about
17% of the earth's atmosphere.

The shielding mass equivalent to the lowest mile of the earth's
atmosphere would be 6 inches of lead, or a little less than 6 feet
of water!

Needless to say, the software was modified to check each memory
word more frequently to correct any errors before they became
multi-bit errors, since we figured we couldn't convince our Denver
customers to install swimming pools above their computer rooms.  ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

Mike Spurgeon wrote:
> Michael J. Mahon wrote:
> 
>> I still remember standing on the foot X-ray in the Thom McCann
>> shoe store, holding the button down and wiggling my toes while
>> peering at the fluoroscope.  ;-)
> 
> 
> That was definitely a late 40's, early 50's thing for me.
> 
> I guess you saw it somewhat later...

Nope--same time!  ;-)

The machines were used primarily during the 1940s and 1950's,
and their use was discontinued in the late 1950s because the
dangers of radiation from the (unshielded) machines was
finally recognized--particularly since children were the
usual targets.

I saw them and played with them in grade school, which
was late 1940s, early 1950s.  ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

Grant Stockly wrote:
>>I must admit to feeling some revival of the desire to build my
>>own X-ray machine.  But I thought that modern CCDs had drastically
>>reduced the "dosage" required to get an exposure.  The several-
>>hundred-RAD territory sounds a bit out of my range.  ;-)
> 
> 
> It was several hundred rad for 16 or so full exposures.  The exposure
> required depends on the pixel size.  That was quite a high resolution
> x-ray.  ;)
> 
> That said, 80kv 6ma is hardly anything.  The tube I was using goes up
> to 160kv 20ma, and it isn't our biggest tube.  We have a tube that goes
> up to 420kv and 10ma.  THAT is a high dose...
> 
> I imagine that an old AM radio tube could make some crude x-rays...  Or
> you could buy an x-ray tube off of ebay.  : )

I just found a nice link describing X-rays made with an 80kV dental
X-ray machine (from eBay) on Polaroid 600 color film:

http://www.noah.org/science/x-ray/polaroid/index.html

and another describing a homemade machine using a flyback transformer
and a Cockroft-Walton multiplier, applied to a receiving tube
(both immersed in oil):

http://www.belljar.net/xray.htm

Looks like we were thinking the same way...  ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."