Tube simulator

[Tom Del Rosso]

From
http://www.stephenwolfram.com/about-sw/interviews/85-sciam/
near the end.

Back in 1948 Robert Heppe of Fairfax, Va., was a freshman electrical
engineer at the Queens, N.Y., plant of the Sylvania Electric Products
Company. Heppe, assigned to assist in the design of vacuum tubes, found the
process onerous. The problem was that one had to specify the size, shape and
placement of the grids and beam-forming plates on paper. The design was then
manufactured in the form of a single tube and tested. This could take
several days. His supervisor, Gerald Rich, improved efficiency by suggesting
a certain analog gadget.

The gadget consisted of a rubber sheet, a dowel, some plywood and several
boxes of toothpicks. The rubber sheet clamped into a large ring represented
the tube cross section magnified many times. The cathode was a wood dowel
poking up in the center of the sheet. Arrays of toothpicks represented
various grid designs. Negative grids tented the sheet up from below;
positive grids depressed the sheet from above. Other aspects of tube
geometry were captured by plywood shapes also imposed from below or above.
Electrons pouring from the cathode were simulated by slowly emptying a can
of BB's over the dowel. "It can be shown," writes Heppe, "that the slope of
the rubber in such a gadget represents the electric field, and the height
represents the voltage in the space between the electrodes.... The BB's
rolled down the sheet [as in] a pin-ball game, some collecting at the plate,
some at the positive grids. If we didn't like how many arrived at the
various electrodes, or which way they went, we could move things around,
change sizes, etc., and try it again." Promising configurations were
embodied and tested in real tubes.


--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

 

[Bob Eldred]

"Tom Del Rosso" <ng01@att.net.invalid> wrote in message
news:_B3pe.904894$w62.95475@bgtnsc05-news.ops.worldnet.att.net...

From
http://www.stephenwolfram.com/about-sw/interviews/85-sciam/
near the end.

Back in 1948 Robert Heppe of Fairfax, Va., was a freshman electrical
engineer at the Queens, N.Y., plant of the Sylvania Electric Products
Company. Heppe, assigned to assist in the design of vacuum tubes, found
the
process onerous. The problem was that one had to specify the size, shape
and
placement of the grids and beam-forming plates on paper. The design was
then
manufactured in the form of a single tube and tested. This could take
several days. His supervisor, Gerald Rich, improved efficiency by
suggesting
a certain analog gadget.

The gadget consisted of a rubber sheet, a dowel, some plywood and several
boxes of toothpicks. The rubber sheet clamped into a large ring
represented
the tube cross section magnified many times. The cathode was a wood dowel
poking up in the center of the sheet. Arrays of toothpicks represented
various grid designs. Negative grids tented the sheet up from below;
positive grids depressed the sheet from above. Other aspects of tube
geometry were captured by plywood shapes also imposed from below or above.
Electrons pouring from the cathode were simulated by slowly emptying a can
of BB's over the dowel. "It can be shown," writes Heppe, "that the slope
of
the rubber in such a gadget represents the electric field, and the height
represents the voltage in the space between the electrodes.... The BB's
rolled down the sheet [as in] a pin-ball game, some collecting at the
plate,
some at the positive grids. If we didn't like how many arrived at the
various electrodes, or which way they went, we could move things around,
change sizes, etc., and try it again." Promising configurations were
embodied and tested in real tubes.


--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

That's the ultimate analog computer. It reminds me of the rubber sheet,
coffee can and dowels to represent poles and zeros on the s-plane. Such an
arrangement gives a very intuitive view of frequency response and how poles
and zeros interact and how their locations and numbers affect cutoff
frequencies, flatness and slopes. Without the rubber sheet model, it was
quite arcane and mathematical and hard for the student to visualize, maybe
it still is? Also rubber sheets can be used to demonstrate gravity, the
fields around planets and stars, how "warpage" of space creates gravity, and
how objects orbit a planet or star. BB's help there also. Lets hear it for
rubber sheets! Some people find sexual uses for them too, but I'll leave it
there.
Bob

 

[Tom Del Rosso]

"Bob Eldred" <nsmontassoc@yahoo.com> wrote in message
news:53123$42a4d503$42a7d082$2294@msgid.meganewsservers.com...

That's the ultimate analog computer. It reminds me of the rubber sheet,
coffee can and dowels to represent poles and zeros on the s-plane. Such an
arrangement gives a very intuitive view of frequency response and how
poles
and zeros interact and how their locations and numbers affect cutoff

Where can I buy/get a rubber sheet like that? I interpreted the description
to mean a fairly thin sheet with some elasticity, but thicker than balloon
material, although they don't specify.

--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

 

[John Larkin]

On Mon, 6 Jun 2005 15:58:29 -0700, "Bob Eldred"
<nsmontassoc@yahoo.com> wrote:

"Tom Del Rosso" <ng01@att.net.invalid> wrote in message
news:_B3pe.904894$w62.95475@bgtnsc05-news.ops.worldnet.att.net...
From
http://www.stephenwolfram.com/about-sw/interviews/85-sciam/
near the end.

Back in 1948 Robert Heppe of Fairfax, Va., was a freshman electrical
engineer at the Queens, N.Y., plant of the Sylvania Electric Products
Company. Heppe, assigned to assist in the design of vacuum tubes, found
the
process onerous. The problem was that one had to specify the size, shape
and
placement of the grids and beam-forming plates on paper. The design was
then
manufactured in the form of a single tube and tested. This could take
several days. His supervisor, Gerald Rich, improved efficiency by
suggesting
a certain analog gadget.

The gadget consisted of a rubber sheet, a dowel, some plywood and several
boxes of toothpicks. The rubber sheet clamped into a large ring
represented
the tube cross section magnified many times. The cathode was a wood dowel
poking up in the center of the sheet. Arrays of toothpicks represented
various grid designs. Negative grids tented the sheet up from below;
positive grids depressed the sheet from above. Other aspects of tube
geometry were captured by plywood shapes also imposed from below or above.
Electrons pouring from the cathode were simulated by slowly emptying a can
of BB's over the dowel. "It can be shown," writes Heppe, "that the slope
of
the rubber in such a gadget represents the electric field, and the height
represents the voltage in the space between the electrodes.... The BB's
rolled down the sheet [as in] a pin-ball game, some collecting at the
plate,
some at the positive grids. If we didn't like how many arrived at the
various electrodes, or which way they went, we could move things around,
change sizes, etc., and try it again." Promising configurations were
embodied and tested in real tubes.

Today's equivalent would be one of those very expensive
charged-particle tracer programs, run in monte carlo mode. *Very*
compute intensive!

--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

That's the ultimate analog computer. It reminds me of the rubber sheet,
coffee can and dowels to represent poles and zeros on the s-plane. Such an
arrangement gives a very intuitive view of frequency response and how poles
and zeros interact and how their locations and numbers affect cutoff
frequencies, flatness and slopes. Without the rubber sheet model, it was
quite arcane and mathematical and hard for the student to visualize, maybe
it still is? Also rubber sheets can be used to demonstrate gravity, the
fields around planets and stars, how "warpage" of space creates gravity, and
how objects orbit a planet or star.
Bob

Another handy analog computer was teledotos paper, a mildly-conductive
carbon-impregnated paper. It was handy for calculating the sheet
resistance of arbitrary shapes, and electric field distributions. The
IC design guys used to use it.

I wish there was an affordable (as in free?) FEA program that would do
the equivalent sheet resistance calcs. That would be handy for a lot
of electrical and thermal situations. I tried adapting ATLC to do it,
but it didn't work very well.

BB's help there also. Lets hear it for
rubber sheets! Some people find sexual uses for them too, but I'll leave it
there.

Trampoline sex?

John

 

Tom Del Rosso <ng01@att.net.invalid> wrote:

Where can I buy/get a rubber sheet like that?

"Dental dam" comes in relatively small squares, but it might do what you
want. Google gives http://www.coltenewhaledent.com/dentdam.htm among
others.

Matt Roberds

 

[John Larkin]

On Mon, 06 Jun 2005 23:27:20 GMT, "Tom Del Rosso"
<ng01@att.net.invalid> wrote:

"Bob Eldred" <nsmontassoc@yahoo.com> wrote in message
news:53123$42a4d503$42a7d082$2294@msgid.meganewsservers.com...

That's the ultimate analog computer. It reminds me of the rubber sheet,
coffee can and dowels to represent poles and zeros on the s-plane. Such an
arrangement gives a very intuitive view of frequency response and how
poles
and zeros interact and how their locations and numbers affect cutoff

Where can I buy/get a rubber sheet like that? I interpreted the description
to mean a fairly thin sheet with some elasticity, but thicker than balloon
material, although they don't specify.

McMaster.

John

 

[Pooh Bear]

John Larkin wrote:

On Mon, 6 Jun 2005 15:58:29 -0700, "Bob Eldred"
nsmontassoc@yahoo.com> wrote:


"Tom Del Rosso" <ng01@att.net.invalid> wrote in message
news:_B3pe.904894$w62.95475@bgtnsc05-news.ops.worldnet.att.net...
From
http://www.stephenwolfram.com/about-sw/interviews/85-sciam/
near the end.

Back in 1948 Robert Heppe of Fairfax, Va., was a freshman electrical
engineer at the Queens, N.Y., plant of the Sylvania Electric Products
Company. Heppe, assigned to assist in the design of vacuum tubes, found
the
process onerous. The problem was that one had to specify the size, shape
and
placement of the grids and beam-forming plates on paper. The design was
then
manufactured in the form of a single tube and tested. This could take
several days. His supervisor, Gerald Rich, improved efficiency by
suggesting
a certain analog gadget.

The gadget consisted of a rubber sheet, a dowel, some plywood and several
boxes of toothpicks. The rubber sheet clamped into a large ring
represented
the tube cross section magnified many times. The cathode was a wood dowel
poking up in the center of the sheet. Arrays of toothpicks represented
various grid designs. Negative grids tented the sheet up from below;
positive grids depressed the sheet from above. Other aspects of tube
geometry were captured by plywood shapes also imposed from below or above.
Electrons pouring from the cathode were simulated by slowly emptying a can
of BB's over the dowel. "It can be shown," writes Heppe, "that the slope
of
the rubber in such a gadget represents the electric field, and the height
represents the voltage in the space between the electrodes.... The BB's
rolled down the sheet [as in] a pin-ball game, some collecting at the
plate,
some at the positive grids. If we didn't like how many arrived at the
various electrodes, or which way they went, we could move things around,
change sizes, etc., and try it again." Promising configurations were
embodied and tested in real tubes.



Today's equivalent would be one of those very expensive
charged-particle tracer programs, run in monte carlo mode. *Very*
compute intensive!

--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

That's the ultimate analog computer. It reminds me of the rubber sheet,
coffee can and dowels to represent poles and zeros on the s-plane. Such an
arrangement gives a very intuitive view of frequency response and how poles
and zeros interact and how their locations and numbers affect cutoff
frequencies, flatness and slopes. Without the rubber sheet model, it was
quite arcane and mathematical and hard for the student to visualize, maybe
it still is? Also rubber sheets can be used to demonstrate gravity, the
fields around planets and stars, how "warpage" of space creates gravity, and
how objects orbit a planet or star.
Bob


Another handy analog computer was teledotos paper, a mildly-conductive
carbon-impregnated paper. It was handy for calculating the sheet
resistance of arbitrary shapes, and electric field distributions. The
IC design guys used to use it.

I wish there was an affordable (as in free?) FEA program that would do
the equivalent sheet resistance calcs. That would be handy for a lot
of electrical and thermal situations. I tried adapting ATLC to do it,
but it didn't work very well.

BB's help there also. Lets hear it for
rubber sheets! Some people find sexual uses for them too, but I'll leave it
there.

Trampoline sex?

John

Since I have to admit that I've met a few of the kinky crowd over the years - try
this one for size !

http://www.vacbed.com/menu.html

Graham

 

[Tom Del Rosso]

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:42A52B45.6DDCA48D@hotmail.com...

Since I have to admit that I've met a few of the kinky crowd over the
years - try
this one for size !

http://www.vacbed.com/menu.html

Graham

That would make it very easy to smother someone without leaving any marks.
I wonder if the coroner would find plastisizer residue all over the body.


--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

 

[Robert Baer]

John Larkin wrote:

On Mon, 6 Jun 2005 15:58:29 -0700, "Bob Eldred"
nsmontassoc@yahoo.com> wrote:


"Tom Del Rosso" <ng01@att.net.invalid> wrote in message
news:_B3pe.904894$w62.95475@bgtnsc05-news.ops.worldnet.att.net...

From
http://www.stephenwolfram.com/about-sw/interviews/85-sciam/
near the end.

Back in 1948 Robert Heppe of Fairfax, Va., was a freshman electrical
engineer at the Queens, N.Y., plant of the Sylvania Electric Products
Company. Heppe, assigned to assist in the design of vacuum tubes, found

the

process onerous. The problem was that one had to specify the size, shape

and

placement of the grids and beam-forming plates on paper. The design was

then

manufactured in the form of a single tube and tested. This could take
several days. His supervisor, Gerald Rich, improved efficiency by

suggesting

a certain analog gadget.

The gadget consisted of a rubber sheet, a dowel, some plywood and several
boxes of toothpicks. The rubber sheet clamped into a large ring

represented

the tube cross section magnified many times. The cathode was a wood dowel
poking up in the center of the sheet. Arrays of toothpicks represented
various grid designs. Negative grids tented the sheet up from below;
positive grids depressed the sheet from above. Other aspects of tube
geometry were captured by plywood shapes also imposed from below or above.
Electrons pouring from the cathode were simulated by slowly emptying a can
of BB's over the dowel. "It can be shown," writes Heppe, "that the slope

of

the rubber in such a gadget represents the electric field, and the height
represents the voltage in the space between the electrodes.... The BB's
rolled down the sheet [as in] a pin-ball game, some collecting at the

plate,

some at the positive grids. If we didn't like how many arrived at the
various electrodes, or which way they went, we could move things around,
change sizes, etc., and try it again." Promising configurations were
embodied and tested in real tubes.





Today's equivalent would be one of those very expensive
charged-particle tracer programs, run in monte carlo mode. *Very*
compute intensive!



--

Reply in group, but if emailing add
2 more zeros and remove the obvious.

That's the ultimate analog computer. It reminds me of the rubber sheet,
coffee can and dowels to represent poles and zeros on the s-plane. Such an
arrangement gives a very intuitive view of frequency response and how poles
and zeros interact and how their locations and numbers affect cutoff
frequencies, flatness and slopes. Without the rubber sheet model, it was
quite arcane and mathematical and hard for the student to visualize, maybe
it still is? Also rubber sheets can be used to demonstrate gravity, the
fields around planets and stars, how "warpage" of space creates gravity, and
how objects orbit a planet or star.
Bob



Another handy analog computer was teledotos paper, a mildly-conductive
carbon-impregnated paper. It was handy for calculating the sheet
resistance of arbitrary shapes, and electric field distributions. The
IC design guys used to use it.

I wish there was an affordable (as in free?) FEA program that would do
the equivalent sheet resistance calcs. That would be handy for a lot
of electrical and thermal situations. I tried adapting ATLC to do it,
but it didn't work very well.


BB's help there also. Lets hear it for
rubber sheets! Some people find sexual uses for them too, but I'll leave it
there.


Trampoline sex?

John

I think i remember that Don Lancaster seems to have a scheme using

Psotscript as the main processor to (visually) solve equi-potential
fields and the like.

 

[John Larkin]

On Tue, 07 Jun 2005 08:07:07 GMT, Robert Baer
<robertbaer@earthlink.net> wrote:

I think i remember that Don Lancaster seems to have a scheme using
Psotscript as the main processor to (visually) solve equi-potential
fields and the like.

The math is actually simple. What's nasty, at least to me, is setting
up the geometry entry/display/edit stuff. I guess a screen full of
colored (according to conductivity) boxes/pixels would do, with some
of them being passive resistors and some being forced potentials.

ATLC uses .bmp files, and allows you to create them with Paint or
whatever. I guess that's the easiest way to go, but it's fairly
awkward in practice.

John

 

[Robert Baer]

John Larkin wrote:

On Tue, 07 Jun 2005 08:07:07 GMT, Robert Baer
robertbaer@earthlink.net> wrote:

I think i remember that Don Lancaster seems to have a scheme using
Psotscript as the main processor to (visually) solve equi-potential
fields and the like.


The math is actually simple. What's nasty, at least to me, is setting
up the geometry entry/display/edit stuff. I guess a screen full of
colored (according to conductivity) boxes/pixels would do, with some
of them being passive resistors and some being forced potentials.

ATLC uses .bmp files, and allows you to create them with Paint or
whatever. I guess that's the easiest way to go, but it's fairly
awkward in practice.

John

I did not read much of DL's PostScript methodology, but it seemsd

that useage was not complicated.
It is at least worth looking into...