[simpits-tech] Saturday update

[Rob Hommel]

This Saturday just in an effort to get a better understanding as to how the
thing worked Gene and myself completely disassembled a 42 in Toshiba rear
projection television. I have always been one to scrounge up things and when
this thing was dumped in my lap of course I was going to take it. I wanted
to see how it worked and what ever parts of it I thought I might have a
later use for I was going to set aside for future use. I think every
Simpitter has this problem, the need to acquire stuff.

The disassemble began with the removal of the front screen, I had thought it
might be a translucent screen that I could make use of later. I was so ever
wrong instead it turned out to be a 42 in fresnel lens. This next summer I
will be in ant burning heaven with this little beastie. You would be
surprised to find out how much fun you can have with a giant magnifying
glass visit the following site and learn more
http://www.channel4.com/entertainment/games/showcards/A/ant_city.html .

Once the giant lens was removed Gene began the process of removal of the
projector lens themselves there we found that each lens was attached to a
small 7 in CRT. I have to assume that each CRT represented a single color of
cyan red and magenta, as the TV was inoperative we were unable to confirm
this and we really did not want to go to the trouble of getting this beast
in working shape. The lens assembly was a bit peculiar in itself as the main
lens itself appeared to be a spherical lens then hidden within the assembly
was a second lens made of plastic which was of a spherical shape as well.
Between the lens and the CRT was another surprise a chamber which was filled
with a fluid. The fluid was very slightly greasy feeling having the
viscosity of water. I assume that the fluid was used to keep the CRT from
over heating and was of a optical neutral material.

The three projector lenses were aim upon an angled trapezoidal shaped mirror
which reflected the image upon the fresnel lens. Hmmm, spherical lenses upon
a trapezoidal mirror onto a fresnel lens which is a spherical lens as well.
They are trying to make use of the spherical lens as an asset instead of a
liability as most find it. A spherical lens has an infinite number of focal
lengths as we all well know. This creates spherical aberration most often
reflected in its color handling but if you have three lenses with three
different paths to the fresnel lens then you have no problem with focal
length. The color aberration problems associated with fresnel lenses goes
away as each lens find its path to the fresnel lens without concern for a
single point source and then the final fresnel lens magnifies the image to
the viewer, no problems, elegant solution.

Another unusual item discovered were the fact that thy made use of a single
flyback transformer to power all three CRT's.

The cabinet was emptied of it's electronics and optics and left me with a
case to make use of. The fact that it was on casters for ease of movement
encouraged me to find a use for it. The over head projector we are using to
create the forward view is currently resting upon a 2X10 suspended by two
ladders this is something which needed to be corrected. The top of the
cabinet was quickly removed and the sides of the cabinet were cut down to
give the proper height needed to accommodate this task The top replaced and
finally a coat of  gray paint was applied to the cabinet.

While I was working on the cabinet Gene amused himself with the task of the
Bit panel. The Bit Panel will require a total of 65 wires as each of the
lamps in the panel itself is really two lamps and the rotary switch is going
to take another awful lot of wires to get it together. The Bit Panel harness
will take more than a thousand feet of wire alone to finish. Gene made the
comment that when he had previously heard comments of Boeing having put 5000
miles of wire into an aircraft he sort of wondered where the heck it all
went. Now we all know the truth they used it.

Well that about sums up the work we did on the Sim that day, we spent the ev
ening watching The Sum of All Fears. A good movie that while it wasn't the
book was a good movie just the same. How did the rest of the crowd spent
their Saturday?

Keep 'em Flying
Rob Hommel


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