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Post by scotttucker on Jul 15, 2022 13:05:54 GMT -7
I posted a few details of this on the Planetarium Enthusiasts facebook page. I will try and make a more comprehensive record here but just to get the ball rolling: After about 17 or more years of occasionally searching for planetarium related stuff on e-bay (as well as attempting to make DIY versions) an extraordinary sale popped up very early one morning in February. Five months on this photograph of it being delivered is still one of my favourites because it reminds me of the excitement & the agonising wait for it to arrive. I half believed it must have been a mistake or a perhaps a scam but sure enough it turned up on a slightly drizzly day about a week after the sale. It is a Goto GE 6S which started life in Leith Nautical College, spent a decade or so at the Manchester Museum of Science and Industry and then made its way via Norfolk and Torquay to Cornwall. By pure chance I had met the son in law of the chap who sold it a couple of years earlier at a music festival - he was in a band called Void Null (who were absolutely excellent) and I got talking to him because their performance happened to be in a geodesic sphere tent and they had very impressive spacey graphics/ imagery as part of the act. He had mentioned his father in law owned a real planetarium projector and even sent me a photo of it but there was no indication he was ever going to sell it. In the end I think the seller was reasonably happy that it had gone to a genuine enthusiast- he said he had many other projects to be getting on with and his wife had told him to get rid of it It came with a manual, circuit diagram and some correspondence from the previous owner in Norfolk (who was very helpful when I later contacted him). The circuit diagram and manual had been supplied to him by incredibly helpful staff at Goto in Tokyo years after production had ceased - they still seemed interested in how their 'children' are doing!
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Post by scotttucker on Jul 15, 2022 13:15:35 GMT -7
The main issues requiring attention were: a) Cleaning (it had about 8 years of dust from sitting in garages) b) A couple of wires had breaks in them or had been severed (pretty minor, the wires to the pole star pointer had seemingly been caught up in the main drive mechanism and was severed) c) Many of the bulbs were missing or had blown (there are a surprising number of different voltages and odd fittings) d) Figuring out how to wire the console to the projector e) damaged diffuser covers f) the lower planetary cage drive motor is a bit misaligned so sticks a little. I have still not finished cleaning it - other than that it is absolutely beautiful
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Post by scotttucker on Jul 15, 2022 13:20:15 GMT -7
It came with an amazingly heavy steel stand. I have started to rather crudely attach some heavy duty wheels to it so that I can move it around more easily. I have used the floor fixing bolts to hold the plywood dolly on it - nothing that cannot simply be unbolted later.
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Post by Ron Walker on Jul 15, 2022 19:15:38 GMT -7
GREAT STUFF!!! I always love it when an old projector is saved from junk or left to rust away. I especially love a projector landing in the hands of someone who will bring it back to life.
I would love to see some close up pictures of the planet cages.
Thank You for the posts.
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Post by scotttucker on Jul 22, 2022 12:58:58 GMT -7
Hi Ron - some close ups as requested: First up a general picture of the upper cage. The largest object on the very top tier is the northern star plate cylinder and bulb. I guess this is the downside of having the cage protrude from the starball - the plate can't be mounted on the starball because the planetary cages would obscure it. I understand the arrangement was chosen as the cage does not have to be as strong mechanically if the starballs are not supported on the ends. The upper cage motor is the shiny cylinder on the left with the two cables attached. Next to that you can just see the inverted cone of the precession circle projector. The top right object is the northern milky way projector and the greenish thing on the far right is the variable resistor which allows you adjust the brightness of the milky way. Then from the next tier down to the bottom is the moon projector (large squarish one), the sun and mercury.
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Post by scotttucker on Jul 22, 2022 13:13:58 GMT -7
Moon Projector: The bulb is held in place by the knurled ring visible in this first view. This shot gives a fairly good view of the slip rings on the uppermost tier. All of the planet projectors project via a mirror at 45 degrees to the projection lens. In the case of the moon the mirror is driven by gears beneath the supporting plate (I think to reproduce the 5 degree tilt against the plate axis). There is a small spherical device at the back of the projector which I think rotates internally and recreates the phases.
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Post by scotttucker on Jul 22, 2022 13:16:53 GMT -7
One more moon picture - lower gears Other close ups to follow
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Post by scotttucker on Jul 23, 2022 0:34:55 GMT -7
Here is a picture of the sun projector (upper) and mercury projector (lower). All the planet projectors are single projector tubes with the image deflected by a small mirror which allows another plane of adjustment. It appears from the gearing that this model does not quite have the sophistication of the zeiss mechanism which has a slotted arm arrangement to capture the more elliptical orbit. The slightly brown coloured disk is the insulator which separates the slip rings from the main plate. The bulbs are mounted at the back and the image focussed by sliding the bulb holder along the main tube.
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Post by scotttucker on Jul 23, 2022 0:38:34 GMT -7
A quick view of the venus projector with the bulb holder and bulb removed. You can just about see the internal lens/plate in the tube which makes the image which is then projected by the projection lens at the front.
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Post by Ron Walker on Jul 23, 2022 9:54:09 GMT -7
It is interesting in the use of the mirror in front of the projector. Originally this was not the case as I did not have them in my E-5 but a later version at Scottsdale Community College did. Now one might think the mirror would make it very easy to adjust the position of the planet on the dome but since that is usually a one time adjustment I have doubts that is the main reason. I'm thinking that it is probably to reduce the effects of the various support rods in the projection of the planets. Basically the further away from the projected image the support rod is, the less darkening or occultation of the projected image. This way they could design the planet unit with only one projector. In the Zeiss, this problem was overcome by using two projectors and designed so that both would never be behind a post at the same time.
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Post by scotttucker on Jul 24, 2022 11:27:33 GMT -7
This weekend I cut and drilled 6 simple steel brackets so that I could bolt the top of the support stand directly to the bottom using existing bolt holes. The original intended design is that the upper support should be attached to the bottom by fitting inside a big steel tube which holds the projector about 2m off the ground. It would be very unhelpful to mount it so high up at the moment and I don't want to cut the tube (or in fact start drilling new holes in it)- hence the simple approach. I enlisted the help of my son to lift the projector on top. Perhaps it does not come across very well in the pictures but there is a huge difference in visual impact/ aesthetics now that the projector sits proudly on a stand rather than on the floor. It looks much more imposing.
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Post by scotttucker on Jul 24, 2022 11:30:29 GMT -7
Forgot to say you can see the mounting tube in the background in the previous picture. A wider view of console and mounted projector:
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Post by scotttucker on Jul 24, 2022 12:08:16 GMT -7
For comparison a grainy but very interesting picture of Dr David Gavine with the projector mounted on the tube in its original installation in Leith (taken from Ahmed Shibley's MSc thesis on the history of UK planetaria).
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Post by Ron Walker on Jul 24, 2022 18:19:36 GMT -7
Normally the east/west axes sits at the spring line and that is usually at a normal room's ceiling level. Very high and imposing but almost too high. Do to building height restrictions I had to put my spring line at five feet. This helped several things. No longer get the feeling that one was looking out of a pit at the sky. The projector being lower does not block as much of the sky. And most importantly you get a better view of the projector which is more important to me.
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Post by scotttucker on Jul 24, 2022 22:22:26 GMT -7
Yes - I thought it looked a bit high too. When I finally get a dome sorted out I can get it to exactly the right height. It should not be too difficult to cut the tube down to the right height.
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