http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

On Thu, 21 Dec 2006 08:57:54 GMT, Burgerman wrote:

http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Does this help:

http://www.howstuffworks.com/stirling-engine.htm

--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail ngpsm4 (at) infohitsystems (dot) ltd (dot) uk

"Burgerman" wrote in message
...
http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Dunno what it's called, but the gadget I've never been able to figure out is
the one that has a rotating vane in a sealed glass container shaped like an
electric light bulb. Powered by light.
Mike.

"rp" wrote in message
news:atcfzvasbuvgflfgrzfygqhx.jamqio0.pminews@ouse ...
On Thu, 21 Dec 2006 08:57:54 GMT, Burgerman wrote:

http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Does this help:

http://www.howstuffworks.com/stirling-engine.htm

--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail ngpsm4 (at) infohitsystems (dot) ltd (dot) uk


Well I read the therory and built one when I was 17 in metalwork at school.
1975!

Still seems like magic!

"Mike G" wrote in message
...

"Burgerman" wrote in message
...
http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Dunno what it's called, but the gadget I've never been able to figure out
is the one that has a rotating vane in a sealed glass container shaped
like an electric light bulb. Powered by light.
Mike.


Can you still get them?
Its the "pressure" of light. Absorbed in the black and reflected from the
white.
But photons have no mass...

Burgerman wrote:
"Mike G" wrote in message
...

Dunno what it's called

Crookes radiometer

but the gadget I've never been able to
figure out is the one that has a rotating vane in a sealed glass
container shaped like an electric light bulb. Powered by light.
Mike.

Can you still get them?

Yep.

http://curiousminds.co.uk/product_in...roducts_id/119

On Thu, 21 Dec 2006 12:49:11 GMT, Burgerman wrote:

"Mike G" wrote in message
...

"Burgerman" wrote in message
...
http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Dunno what it's called, but the gadget I've never been able to figure out
is the one that has a rotating vane in a sealed glass container shaped
like an electric light bulb. Powered by light.
Mike.


Can you still get them?
Its the "pressure" of light. Absorbed in the black and reflected from the
white.


Umm no, that's not how they work (sadly) although light pressure is a real
phenomenon. The vanes on a Crookes Radiometer are too small to get much of
a push from light pressure and the pressure would be greater on the white
patch than on the black. So if light pressure were the cause the rotation
would have the white patch on the trailing edge. As it is, they are the
other way around, the "push" comes from the black side.

The vanes are in a vacuum, but the vacuum isn't perfect, just good at about
10^-2 torr. Hence there are some gas molecules in there, just not many. The
vaccuum is good enough to reduce air friction on the vanes significantly.
When exposed to light, the dark side of the vane absorbs photons and warms
up slightly. Any air molecule hitting that side of the vane departs with
slightly more energy than it had. Any air molecule hitting the white side
of the card leaves with about the same (or slightly less) energy than it
had. This isn't enough to cause an imbalance in force big enough to make
the vanes turn, but at the edges of the vane there are effects where the
molecules of air move from the cold side to the hot side past the edge of
the vane. The sum of these forces causes an imbalance in force on the two
sides of the vane and it rotates.

Confirmation of this effect can be shown by evacuating more air from the
bulb. By the time you get to 10^-6 torr the vanes stop moving.


But photons have no mass...

But they do have a lot of energy.

"Steve Firth" wrote in message
...
On Thu, 21 Dec 2006 12:49:11 GMT, Burgerman wrote:

"Mike G" wrote in message
...

"Burgerman" wrote in message
...
http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Dunno what it's called, but the gadget I've never been able to figure
out
is the one that has a rotating vane in a sealed glass container shaped
like an electric light bulb. Powered by light.
Mike.


Can you still get them?
Its the "pressure" of light. Absorbed in the black and reflected from the
white.


Umm no, that's not how they work (sadly) although light pressure is a real
phenomenon. The vanes on a Crookes Radiometer are too small to get much of
a push from light pressure and the pressure would be greater on the white
patch than on the black. So if light pressure were the cause the rotation
would have the white patch on the trailing edge. As it is, they are the
other way around, the "push" comes from the black side.

The vanes are in a vacuum, but the vacuum isn't perfect, just good at
about
10^-2 torr. Hence there are some gas molecules in there, just not many.
The
vaccuum is good enough to reduce air friction on the vanes significantly.
When exposed to light, the dark side of the vane absorbs photons and warms
up slightly. Any air molecule hitting that side of the vane departs with
slightly more energy than it had. Any air molecule hitting the white side
of the card leaves with about the same (or slightly less) energy than it
had. This isn't enough to cause an imbalance in force big enough to make
the vanes turn, but at the edges of the vane there are effects where the
molecules of air move from the cold side to the hot side past the edge of
the vane. The sum of these forces causes an imbalance in force on the two
sides of the vane and it rotates.

Confirmation of this effect can be shown by evacuating more air from the
bulb. By the time you get to 10^-6 torr the vanes stop moving.


But photons have no mass...

But they do have a lot of energy.

Well whatever magic it uses I just ordered one.

"Burgerman" wrote in message
...

"Steve Firth" wrote in message
...
On Thu, 21 Dec 2006 12:49:11 GMT, Burgerman wrote:

"Mike G" wrote in message
...

"Burgerman" wrote in message
...
http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top box!

And I am buggered if I can fathom how it works...

Dunno what it's called, but the gadget I've never been able to figure
out
is the one that has a rotating vane in a sealed glass container shaped
like an electric light bulb. Powered by light.
Mike.


Can you still get them?
Its the "pressure" of light. Absorbed in the black and reflected from
the
white.


Umm no, that's not how they work (sadly) although light pressure is a
real
phenomenon. The vanes on a Crookes Radiometer are too small to get much
of
a push from light pressure and the pressure would be greater on the white
patch than on the black. So if light pressure were the cause the rotation
would have the white patch on the trailing edge. As it is, they are the
other way around, the "push" comes from the black side.

The vanes are in a vacuum, but the vacuum isn't perfect, just good at
about
10^-2 torr. Hence there are some gas molecules in there, just not many.
The
vaccuum is good enough to reduce air friction on the vanes significantly.
When exposed to light, the dark side of the vane absorbs photons and
warms
up slightly. Any air molecule hitting that side of the vane departs with
slightly more energy than it had. Any air molecule hitting the white side
of the card leaves with about the same (or slightly less) energy than it
had. This isn't enough to cause an imbalance in force big enough to make
the vanes turn, but at the edges of the vane there are effects where the
molecules of air move from the cold side to the hot side past the edge of
the vane. The sum of these forces causes an imbalance in force on the two
sides of the vane and it rotates.

Confirmation of this effect can be shown by evacuating more air from the
bulb. By the time you get to 10^-6 torr the vanes stop moving.


But photons have no mass...

But they do have a lot of energy.

Well whatever magic it uses I just ordered one.


[edit] Explanations for the force on the vanes
Over the years, there have been many attempts to explain how a Crookes
radiometer works:

1.. Crookes incorrectly suggested that the force was due to the pressure
of light. This theory was originally supported by James Clerk Maxwell who
had predicted this force. This explanation is still often seen in leaflets
packaged with the device. The first experiment to disprove this theory was
done by Arthur Schuster in 1876, who observed that there was a force on the
glass bulb of the Crookes radiometer that was in the opposite direction to
the rotation of the vanes. This showed that the force turning the vanes was
generated inside the radiometer. If light pressure was the cause of the
rotation, then the better the vacuum in the bulb, the less air resistance to
movement, and the faster the vanes should spin. In 1901, with a better
vacuum pump, Pyotr Lebedev showed that in fact, the radiometer only works
when there is low pressure gas in the bulb, and the vanes stay motionless in
a hard vacuum. Finally, if light pressure were the motive force, the
radiometer would spin in the opposite direction as the photons on the shiny
side being reflected would deposit more momentum than on the black side
where the photons are absorbed. The actual pressure exerted by light is far
too small to move these vanes but can be measured with devices such as the
Nichols radiometer.
2.. Another incorrect theory was that the heat on the dark side was
causing the material to outgas, which pushed the radiometer around. This was
effectively disproved by both Schuster's and Lebedev's experiments.
3.. A partial explanation is that gas molecules hitting the warmer side of
the vane will pick up some of the heat i.e. will bounce off the vane with
increased speed. Giving the molecule this extra boost effectively means that
a minute pressure is exerted on the vane. The imbalance of this effect
between the warmer black side and the cooler silver side means the net
pressure on the vane is equivalent to a push on the black side, and as a
result the vanes spin round with the black side trailing. The problem with
this idea is that the faster moving molecules produce more force, they also
do a better job of stopping other molecules from reaching the vane, so the
force on the vane should be exactly the same - the greater temperature
causes a decrease in local density which results in the same force on both
sides. Years after this explanation was dismissed, Albert Einstein showed
that the two pressures do not cancel out exactly at the edges of the vanes
because of the temperature difference there. The force predicted by Einstein
would be enough to move the vanes, but not fast enough.
4.. The final piece of the puzzle, thermal transpiration, was theorized by
Osborne Reynolds, but first published by James Clerk Maxwell in the last
paper before his death in 1879. Reynolds found that if a porous plate is
kept hotter on one side than the other, the interactions between gas
molecules and the plates are such that gas will flow through from the cooler
to the hotter side. The vanes of a typical Crookes radiometer are not
porous, but the space past their edges behave like the pores in Reynolds's
plate. On average, the gas molecules move from the cold side toward the hot
side whenever the pressure ratio is less than the square root of the
(absolute) temperature ratio. The pressure difference causes the vane to
move cold (white) side forward.
Both Einstein's and Reynolds's forces appear to cause a Crookes radiometer
to rotate, although it still isn't clear which one is stronger.

See also: photophoresis.



And yes I know its html but I dont care...

"Burgerman" wrote in message
...

"Burgerman" wrote in message
...

"Steve Firth" wrote in message
...
On Thu, 21 Dec 2006 12:49:11 GMT, Burgerman wrote:

"Mike G" wrote in message
...

"Burgerman" wrote in message
...
http://www.ltd-stirling.de/index.htm

you can get these cheaper on ebay.

I have one running for 10 days solid sat on top of my ntl set top
box!

And I am buggered if I can fathom how it works...

Dunno what it's called, but the gadget I've never been able to figure
out
is the one that has a rotating vane in a sealed glass container shaped
like an electric light bulb. Powered by light.
Mike.


Can you still get them?
Its the "pressure" of light. Absorbed in the black and reflected from
the
white.


Umm no, that's not how they work (sadly) although light pressure is a
real
phenomenon. The vanes on a Crookes Radiometer are too small to get much
of
a push from light pressure and the pressure would be greater on the
white
patch than on the black. So if light pressure were the cause the
rotation
would have the white patch on the trailing edge. As it is, they are the
other way around, the "push" comes from the black side.

The vanes are in a vacuum, but the vacuum isn't perfect, just good at
about
10^-2 torr. Hence there are some gas molecules in there, just not many.
The
vaccuum is good enough to reduce air friction on the vanes
significantly.
When exposed to light, the dark side of the vane absorbs photons and
warms
up slightly. Any air molecule hitting that side of the vane departs with
slightly more energy than it had. Any air molecule hitting the white
side
of the card leaves with about the same (or slightly less) energy than it
had. This isn't enough to cause an imbalance in force big enough to make
the vanes turn, but at the edges of the vane there are effects where the
molecules of air move from the cold side to the hot side past the edge
of
the vane. The sum of these forces causes an imbalance in force on the
two
sides of the vane and it rotates.

Confirmation of this effect can be shown by evacuating more air from the
bulb. By the time you get to 10^-6 torr the vanes stop moving.


But photons have no mass...

But they do have a lot of energy.

Well whatever magic it uses I just ordered one.


[edit] Explanations for the force on the vanes
Over the years, there have been many attempts to explain how a Crookes
radiometer works:

1.. Crookes incorrectly suggested that the force was due to the pressure
of light. This theory was originally supported by James Clerk Maxwell who
had predicted this force. This explanation is still often seen in leaflets
packaged with the device. The first experiment to disprove this theory was
done by Arthur Schuster in 1876, who observed that there was a force on
the glass bulb of the Crookes radiometer that was in the opposite
direction to the rotation of the vanes. This showed that the force turning
the vanes was generated inside the radiometer. If light pressure was the
cause of the rotation, then the better the vacuum in the bulb, the less
air resistance to movement, and the faster the vanes should spin. In 1901,
with a better vacuum pump, Pyotr Lebedev showed that in fact, the
radiometer only works when there is low pressure gas in the bulb, and the
vanes stay motionless in a hard vacuum. Finally, if light pressure were
the motive force, the radiometer would spin in the opposite direction as
the photons on the shiny side being reflected would deposit more momentum
than on the black side where the photons are absorbed. The actual pressure
exerted by light is far too small to move these vanes but can be measured
with devices such as the Nichols radiometer.
2.. Another incorrect theory was that the heat on the dark side was
causing the material to outgas, which pushed the radiometer around. This
was effectively disproved by both Schuster's and Lebedev's experiments.
3.. A partial explanation is that gas molecules hitting the warmer side
of the vane will pick up some of the heat i.e. will bounce off the vane
with increased speed. Giving the molecule this extra boost effectively
means that a minute pressure is exerted on the vane. The imbalance of this
effect between the warmer black side and the cooler silver side means the
net pressure on the vane is equivalent to a push on the black side, and as
a result the vanes spin round with the black side trailing. The problem
with this idea is that the faster moving molecules produce more force,
they also do a better job of stopping other molecules from reaching the
vane, so the force on the vane should be exactly the same - the greater
temperature causes a decrease in local density which results in the same
force on both sides. Years after this explanation was dismissed, Albert
Einstein showed that the two pressures do not cancel out exactly at the
edges of the vanes because of the temperature difference there. The force
predicted by Einstein would be enough to move the vanes, but not fast
enough.
4.. The final piece of the puzzle, thermal transpiration, was theorized
by Osborne Reynolds, but first published by James Clerk Maxwell in the
last paper before his death in 1879. Reynolds found that if a porous plate
is kept hotter on one side than the other, the interactions between gas
molecules and the plates are such that gas will flow through from the
cooler to the hotter side. The vanes of a typical Crookes radiometer are
not porous, but the space past their edges behave like the pores in
Reynolds's plate. On average, the gas molecules move from the cold side
toward the hot side whenever the pressure ratio is less than the square
root of the (absolute) temperature ratio. The pressure difference causes
the vane to move cold (white) side forward.
Both Einstein's and Reynolds's forces appear to cause a Crookes radiometer
to rotate, although it still isn't clear which one is stronger.

See also: photophoresis.



And yes I know its html but I dont care...


Well it was when I posted it!!!