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Portable Planetarium Hardware Adaptations,Considerations, and Care

by John T. Meader, Northern Stars Planetarium, Fairfield, Maine 1995


ORIGINS OF THE IDEA

In 1985, at the Spitz Summer Institute, fellow planetarian Jordan Marche listened to my wife and me talk about our dreams of bringing a planetarium to central Maine. At that point we were thinking big, a new permanent facility. Jordan suggested that, perhaps as a stepping stone, we should consider buying a Starlab portable planetarium. Maybe you could run it as a small business he said. Perhaps, we agreed politely. We looked at each other and neither of us wanted to settle for just a Starlab. Our dreams were bigger, or so we thought. But like so many good ideas, this one took some time to sink in.

On the long drive back to Maine we tossed around Jordan's idea. We knew that to make a living and not go absolutely stir crazy with a Starlab, we would have to design some peripherals that would enable us to expand our offerings. We wondered, how much stuff can you reasonably tote around with a Starlab? How could we make it modular, reliable and easy, as well as quick to set up and take down? So we made a set of criterion that any and all peripherals would have to meet. First, we couldn't afford to buy or build things that were for too specific a use. In other words, we didn't need any special effects projectors that would be good for only one show. Everything had to be useful in numerous different show productions. Second, whatever the final configuration, everything had to be quick and easy to set up. We decided that total set-up time should not exceed one hour, and it would be even better if it were between thirty and forty-five minutes. Third, we wanted our finished product to be modular; in other words, easy to set up without lots of projector aligning required and without carrying around lots of small loose projectors. Everything had to be attached solidly to, or inside of, carryable cases.

At this point we made a wish list of what would be nice to have. Then we pared things down to just those things that met the above criterion. Then we pared it down further to what we could afford.

THE HARDWARE

The selection process lead us to purchasing four Ektagraphic IIIe slide projectors. Two of these would be in a dissolve rack that would be built into a movable case; these two projectors would provide a cross fade in the southern sky. The third projector would go into a second projection case that would project to the southeast. The fourth projector would be placed in the center of the planetarium beside the star projector. It would project toward the west.

We also decided on fifteen special effect projectors. We bought four Talent brand projectors from Sky Skan, Inc., of Nashua, New Hampshire: an aurora, a sunset, a meteor shower, and an evolution of a star. The Talent brand projectors were ideal for a portable planetarium use because they are physically small, low wattage, and quiet (they lack fans); unfortunately, Steve Savage of Sky Skan says he no longer carries them. I also bought a rainbow projector and a strobe for lightning flashes, explosions, etc. Purchasing ready made special effects is relatively expensive, so I built a number of special effects myself, utilizing old film strip projectors, spare parts, and specifically purchased parts. These projectors include a rotating earth, a slide rotator with an anamorphic lens, a slew, a blur wheel, clouds, rain, meridian, milky way, and a shadow panorama projector. Recently, we have also expanded our hardware to include a VCR with a LCD video projector.

To contain and control all these projectors I designed a console. The console was built similar to the control consoles I worked with at the two permanent facilities that I had been associated with, the Francis Malcolm Institute's planetarium and the Jordan Planetarium at the University of Maine. I had been involved with the design and construction of the consoles at both of these facilities, so for my own portable console I simply scaled down the size and the number of controls. All the special effects were then bolted into place either inside the console or inside the modular box that contained the slide projector that projects to the southeast. In this way, setting up became very easy, just put the modular boxes and console in place, connect the cables, and plug in the console. Everything is automatically in focus and ready to use. The layout inside the dome when assembled is illustrated in Figure 1.

 

Dome Layout
Figure 1. Northern Stars Planetarium general layout of projectors, cables, carpets, and dome.

THE CONTROL CONSOLE

The control console was designed to sit in the center of the dome. It was built to serve several functions. First, as already mentioned, it housed a number of the special effects projectors. Second, it served as a base for the star projector and a westerly directed slide projector. Third, it was to be the mechanism that controlled every projector in the planetarium. The north facing side has a dark Plexiglas plate set at a slight angle. This plate was drilled to hold toggle switches, dimmers, and 12 volt D.C. controls. This panel would control the remote slide projectors and all the special effects projectors. The layout of the console control panel is illustrated in Figure 2. The size and shape of the console can be seen in Figure 3. The south side of the console contains an access door and several projection window ports. On the east and west sides of the console are some switched AC outlets and three 12 volt D.C. outlets. On

 

Control Console Diagram
Figure 2. The control console created for the Northern Stars Planetarium.

 

the north face, below the Plexiglas control panel is on non-switchable A.C. outlet, two ammeters to measure the current drawn on the two incoming cords, a projection port for the aurora projector, an hours of use dial, and one momentary button. The momentary button fires the strobe that is flush mounted on the top surface of the console. The switch is mounted here so that it can be fired with the knee, freeing the hands for other things during those dramatic transitions!

 


Figure 3. The dimensions, given in inches, of the control console of the Northern Stars Planetarium. Total weight: 65 lbs.

EKTAGRAPHIC IIIe SLIDE PROJECTORS & DIMMERS

We picked Kodak Ektagraphic IIIe slide projectors because they offered us features that we needed in a slide projector. They had to be able to forward, reverse, focus, and dim remotely. We also did not want auto-focus. Auto-focus uses an internal light to maintain focus. This is not a problem for a general slide show, but in a very dark star theater there is a ghostly rectangular glow which is not wanted in the planetarium.

For dimmers we chose KBGE Series Solid State A.C. Variable Voltage Control Assemblies rated at 15 amperes. These were used in conjunction with a 250 K Potentiometer with a Linear Taper (Part #53C3-250K). Both of these parts are available at Midwest Associates of Rockford, Illinois, (815) 962-8036. The voltage assembly sold for under $25.00 and the potentiometers were less than $10.00 each. I have used these dimmers steadily since 1987, and not one has yet failed.

One more suggestion. Use the lower wattage EXY bulbs in the Ektagraphics. They are slightly more expensive than the higher watt standards, but they last years. In a portable planetarium the added wattage is not needed as the greatest projection distance is only sixteen feet.

THE DOME

We also made some slight modifications to the dome. First, we still use the old square utility type fans. I understand that Learning Technologies has a new fan system that works very well; however, I have modified my system using the "old type" fans and I am completely satisfied with it's performance. I use two fans, one blowing through the other. They are velcroed together. I found that one fan was not sufficient to maintain a tight dome with the fan blowing in the low position, while I found the medium setting to be too loud. The answer was to use two fans. Two fans, blowing on low, will hold the dome up with a minimum of wrinkles, while maintaining a lower noise level than a single fan set at medium. Another nice feature about this method is that if a fan should fail, you have a back-up immediately available. A second fan can be purchased for under $40.00 from Grainger® (part #4C418). Of course, you do have to attach your own snaps. If you do use two fans, it's important to remember to always keep them both set to the same setting; we have discovered that having one set on low and one set on medium is very hard on the motors. We had a motor burn out that way, so keep them set at the same setting and you shouldn't have any problems.

We have also attached Velcro tabs on each seam along the spring-line (the horizon) on the inside of the dome. This allows the placement of glow-in-the-dark cardinal points and other attachments.

CARE & THE COLD

Our dome is eight years old and we have had nearly 100,000 students through it in those years. It is certainly showing some hard wear after all those knees and feet crawling through it. To prolong it's life as long as possible we have done a few things, and will do a few things differently when we get our next dome. First, we have the kids take their shoes off before entering. This rule cuts down grime from shoes and boots, and it also makes everyone more comfortable sitting on the floor for an hour. This is not a hard and fast rule, sometimes it is dropped if the day's schedule is really tight or if the principal tells me there will be a fire drill or if it is a junior high school with a lot of traffic through the gym--I don't want any $100.00 sneakers stolen.

To repair pin holes we only use the little patches that Learning Tech. provides for quick fixes. We have found that children will pick patches off the dome nearly as quickly as we can put them on. For a more permanent fix Sue Reynolds of Onondaga-Cortland-Madison B.O.C.E.S. Planetarium in Syracuse, New York suggested fabric paint. This works great. It is quite durable, although mixing an appropriate color of gray is a bit of a trick. For seams that open, we use the standby--duct tape. Duct tape is the perfect color, but it does have to be replaced every month or so, it slowly peels up around the edges.

One last note on dome wear and tear, we have noticed that the entrance tube and where kids sit takes the most abuse. Beyond the regular pin holes, we have found that the fabric often gets stiff and separates into it's composite layers. We have developed a theory that this is probably due, in large part, to the oils from hands. We have started to experiment with different cleaning fluids for cleaning these surfaces. We are hoping that this will remove some oils and keep the material more supple.

Projectors also require additional care above and beyond the regular cleanings and maintenance when traveling. Our planetarium is seldom left overnight in a school, so it spends its nights (real nights that is) packed in the back of my van. The van is parked in a barn, but in Maine in January it's not uncommon for it to drop to -15° F. This past winter our coldest night was -35°; in my van, in the barn, it was slightly warmer, about -25°. Have you ever turned on a slide projector that is twenty degrees below zero? I'll tell you, nothing good happens. The fan doesn't turn, but the lamp will come on; however, that would be a bad move. If the lamp doesn't shatter, a lens or mirror just might! So what do you do? You need those projectors to be up and running at 8:45. That's why you must have a vehicle with a good heater to at least get those projectors warmed up above freezing. When you get them inside the school, open up the cases you have them in and let the air at them. Once they are in place and plugged in, turn the projector's fans on, but do not turn on the lamps. The slower you bring them up to temperature the easier it will be on the lenses and lamps inside. Condensation is also a problem with cold lenses, again air flow seems to solve the problem as quickly as just about anything. Be very careful if you should decide to wipe the condensation off.

The dome's blower fans sometimes need to be warmed up this way too. As soon as you get them inside, turn them on and just let them run without the load of the dome. Also unroll the dome and let it lie there exposed to the warmth of the room. The dome's fabric gets very stiff when it is extremely cold.

Cassette tape decks also like to be warmed up when cold. I usually plug mine in and open the carriage gate (where you put the cassette). Then I press fast-forward and let it run without a tape in the machine. I press fast-forward because that is the only setting that my Bose Acoustic Wave® will run on without a cassette in the carriage. If this procedure is not done when the machine is cold, it runs slowly.

Laser pointers like to be warmed up in a hip pocket. I think they just like to be next to my wallet to remind me how much they cost! Actually, it's the batteries that need warming, but it's easier to just slide the whole pointer in a pocket.

The video projector is the most sensitive to cold. It just doesn't like it. In reality, I don't think it is so much the cold as the condensation that forms when it hits the warm moist air inside the school. When that happens, it might not run all day. For that reason, when it is cold outside, the video equipment must come in for the night. It's my only equipment that doesn't live in the van during the winter.

CONCLUSION: REMEMBER WHAT'S REALLY IMPORTANT

At a glance, it might seem that I rely too heavily on my equipment. Where's the personal touch? Ultimately, no matter what hardware you may have, the most important piece of equipment you carry with you is you. This may sound a bit cliché, but it's true. If you've seen planetarium shows at different planetariums across the country, you know that not all shows are equal; further more, you've probably also noticed that having the most advanced equipment doesn't necessarily give you the best productions. In the right hands, all those fancy gadgets can really dance; in the wrong hands, they just add confusion. Don't add things to your set-up unless you're comfortable with their appropriate use. Ultimately, in a Starlab or any small planetarium, you are the show. All those fancy do-dads can only do their job well if you can do your job well.

When we advertise our business, Northern Stars Planetarium, we don't try to sell the fact that we have lots of projectors or technology. We don't advertise our product as a Starlab either. I don't sell Starlabs and I don't let the fact that I use a Starlab be my drawing card. Don't get me wrong, I love my Starlab, it's a great piece of equipment, but when it comes to my business I sell me, my expertise, and my programs. I want my clients to want me to return to their school, not just any portable planetarium. Remember, the most important hardware you have is you.

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Northern Stars Planetarium and Educational Services
Fairfield, ME 04937
(207) 453-7668
info@northern-stars.com

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