I made this star map last year for my wife, and everyone who sees it wants to know how it was made.
Be warned, to build something like this is a *big* project. You should expect to know:
* Basic woodworking skills
* How to handle a soldering iron
* How to design LED-based circuits
* How to safely deal with AC voltages
And above all, you'll need plenty of spare time.
This star map is a little over 2m wide, and 1.2m tall. It weighs 12-15kg, has somewhere between 1500-2000 optical fiber stars, and 108 LED stars.
You could quite easily use some of the techniques in here to make a small version, and it would still look really nice. This instructable then, can be used as a general reference for building star maps, not just how to replicate mine exactly. There is some additional info for small maps in the Addenda section.
Step 1: Materials - Optical Fibers
You can buy optical fiber by the reel, but there are better and cheaper ways to get it*: For large star maps; a fake Christmas tree works very well! This time of year, it's not hard to find one cheaply.
For smaller star maps; the retro-tastic 'UFO Lamps' are a great source of fibers, and are pretty easy to find in dollar stores.
Both of these sources are great! They are cheap, and they terminate all the fibers into one place, so it is easy to light the stars.
* The more stars you have, the better it will look. Try to find a tree or lamp with plenty of 'points'.
* The size of the tree/lamp will determine how large your map can be. For example, if you have a 120cm / 4ft tree, you can build a map about 2m / 6.5ft wide. (Of course, the exact shape of the tree and your frame will affect the maximum. Get your measurements right before you buy/cut anything expensive. ;-) )
[*] Some fiber-by-the-reel is sold here. The 0.5mm fiber is probably the closest to what is found in trees/lamps, and costs 8c/ft, or 2c/ft if you buy 19,680ft worth. A $5 UFO lamp might have 400 x 1ft strands, already cut and terminated - at 1.25c/ft.
Step 2: Materials - Light Sources
For smaller maps, you might find an array of 5mm high-brightness LEDs quite appropriate, but I needed something bigger: A 3W LED spot ( http://www.dealextreme.com/details.dx/sku.15070 ). This bulb runs off AC voltage, and generates a narrow beam - perfect for illuminating the terminator. Unlike a halogen bulb, it will last for years, and use about a tenth of the power.
It is not ideal to have all of the stars be the same brightness. In my case I wanted to highlight the constellations, so those brighter stars had a small 3mm or 5mm LED dedicated to each one. A smaller star map may be better off using LEDs with a small integrated light-pipe for constellation stars.
As poster little red suggested; you could alternatively use a store-bought string of LED lights if you're not confident in designing your own circuit. This might work out well, just remember that LED strings are usually a constant distance apart, so there could be a lot of splicing to do to make them reach your constellations.
Step 3: Materials - Everything Else
* A frame. If making a small map, you can use a store-bought picture frame. At large sizes, you'll need to make it yourself.
* Substrate - something that the fibers will be poked through. I used a large piece of double-thick corrugated cardboard, covered in black cloth. You could also use thin plywood, or as commenter astack suggested; foam-core board.
* Backing - something to stop light leaking out behind the frame. I used black cloth.
* Power supply and control circuitry - This depends on your light sources. It could simply be a battery and an on/off switch. Mine is a little more involved, read on for more info.
To build a map just like mine, you will need:
* Lumber : Lengths in the frame width you want, and smaller pieces for the inner frame.
* Fasteners : Screws and right-angle brackets
* Stain : Black stain to get the frame the right colour.
* A refridgerator or air-conditioner box - something big and cardboard.
* Cloth: Black cotton drill, or anything that doesn't stretch, and blocks light well.
* Fiber-optic christmas tree
* 3W LED spotlight
* 108 white LEDs, other associated components (wire, resistors, etc)
* 30V DC power supply (or similar)
* RF switch module
* Heatshrink and acrylic rod
* Tools: Hand-saw, clamps, screwdriver, box cutter, side-cutters, pliers, a needle, plenty of tape, wood glue, stapler, multimeter, bench power supply, breadboard
* Lots of patience
Step 4: Planning and Design
Due to the large size of this star map, the frame is built in two pieces - an inner and outer frame. The outer frame is what the audience sees, and will be stained black. The inner frame supports the cardboard substrate and fabric front, and is hidden behind the outer frame. (See second diagram for cross-section)
Step 5: Planning and Design: It's Full of Stars!
* Download and install Celestia. ( www.shatters.net/celestia )
* Go to Render->View Options... , switch off Planets, and show Constellation diagrams.
* Go to Render->Star Style, and select 'Scaled Discs'
Now, find the area of sky that you wish to display. Using "[" and "]" you can adjust the number of stars shown, and using "," and "." you can adjust the field of view (FOV). To capture the image, go to full-screen mode (Alt+Enter) and press F10.
Getting the right number of stars might be a bit tricky. If you have too many stars visible you may run out of fibers three quarters of the way through construction. If you have too few you'll end up with a sparser star map, and lots of left-over fibers. I suggest taking a sample image, counting every star in a small fraction of the image, and extrapolating from that to estimate the total number of stars.
So, find yourself a pretty section of sky, and save a nice high-resolution image. How do you get that design onto the star map? Read on...
Note: Some commenters have also suggested interesting alternatives. Makendo suggested a fiber-optic map in the shape of a 2001: A Space Odyssey Monolith. Astack suggested using the NASA image 'Earth at Night'. There are many interesting patterns this fiber-optic art form could use.
Step 6: Building the Frames
The Outer frame: From 200x19mm pine (or a decorative wood if desired) build a flat miter-jointed frame, with the same internal space. Again, this frame will be seen, so it can be decoratively built if desired. As the second picture shows, these pieces are kept together with angled plates. A taut strap around the outside of the frame will help keep it square until the angle plates are attached.
Turn the outer frame over. Place the inner frame on top of the outer frame. Drill pilot holes and screw the two frames together from the back (so that no screws or holes will be visible in the front when the frame is completed)
Step 7: Painting the Frame
Paint or stain the frame according to your preference and the instructions on the can. I put a coat of sealant on the wood, then five coats of black stain to get a nice almost-black finish.
Step 8: Attaching the Substrate
Once secured in place, trim around the outside of the frame to make the substrate flush with the edges.
If you look at the picture below, you can see that I have used two pieces of cardboard to cover the frame. I don't recommend this, use a single large flat piece if at all possible. If your substrate is not perfectly flat or slightly convex, there will be air gaps between the substrate and the cloth. Air gaps make it harder to feed fibers through, and make it difficult to cut the fibers to the right length.
Step 9: Attaching the Front Material
I covered the front of my star map in black cotton drill. To stretch the material over the frame is fairly simple, and is done in the same way as stretching canvas. This instructable by Gburg_06 shows in more detail how to do this, but put simply:
* Stretch the canvas out flat and staple to the back of the frame.
* Start at the center of each side, and gradually move to each corner.
* Again, avoid placing staples over the screw holes.
Cotton drill is not as tough a material as canvas, so it may also help to fold the edge of the fabric over before stapling through it.
Step 10: Attaching the Map to the Back of the Substrate
Then, using PosteRazor ( http://posterazor.sourceforge.net/ ) or a similar tool, scale your image up to the right size for the map, print it onto multiple pieces of paper, and trim off the margins. Using thinned wood glue, glue each page to the back of the frame. Now you can use the enlarged image as a template to place all the star points.
(Remember, it must be mirrored, or you will end up placing all of your constellations backwards!)
Step 11: Chop Down the Christmas Tree!
* Box cutter
The goal here is to remove the tree from the fibers. Most trees are constructed from steel rod (the trunk), wire (for the branches), and the leaves; stuff that looks like, but is not quite, tinsel. The fibers run right up the middle of everything (of course), so to remove the fibers you have to disassemble the whole tree.
Starting at the bottom, carefully break open some of the material wrapped around the trunk, and start unwinding. There will be lots of sticky-tape holding it in place, but just carefully peel the 'leaves' back. Each branch will have a similar arrangement, just continue peeling back the 'leaves' until there is none left. Now, you will have to remove any other sticky-tape holding the tree together, and the fibers should be left on their own. Many many many hours later, you will have something like this left.
When the tree has been taken apart, try to group fibers of similar lengths together - this will make it easier when building the map.
Step 12: Mounting the Terminator and Light Source
Screw a clean food tin to the support, and mount the LED spotlight so that it is centered inside the tin. Using a centering spacer made of wood and a pipe clamp, fix the terminator to the support so that it lines up with the spotlight, at a distance so that the entire terminator is lit, but there is not too much light spillage. It will help to determine this optimal distance *before* attaching anything together!
(The LED spotlight is fixed inside a standard GU10 AC socket, and attached to a bracket I happened to have lying around. You could use a wooden spacer and a pipe clamp to achieve a similar effect.)
Step 13: Initial Fiber Placement
It may help to use highlighter pens to divide the star map into radial 'sectors'. Each sector thus needs approximately the same number of fiber bundles at each distance.
Step 14: Poking Through and Gluing the Fibers
For each small point of light, poke a hole through the substrate with a heavy-duty needle. Thick cardboard is tough, so you will need to push the needle through with the help of a pair of pliers. See the MkII-hole-poking-device in the second picture, it will make your life much easier! (If you are using something tougher, like plywood, you will need to drill hundreds if not thousands of tiny holes with a drill. Good luck. :-) )
Gently feed a single fiber through the hole you have just made. If you have thick cardboard or fabric on the front you may need to twist the fiber carefully to poke it through. If you push too hard, the fiber will kink. If this happens, trim below the kink and try again. Once through, keep pushing the fiber in until there is just a little slack left on the back side. It helps to feel on the other side so you know when the fiber has gone through properly. (Take care that the fiber doesn't get misdirected down a corrugation of the cardboard)
Using wood glue, apply a drop to the fiber where it feeds through the back of the hole. (IT MUST BE WOOD GLUE! If you use anything with solvents, like super glue, the fibers will craze internally and stop transmitting light properly.)
Of course, it is best to punch lots of holes in one go, then poke through lots of fibers, then glue a lot, then repeat. And repeat. Aaand repeat. Take breaks occasionally, because constantly gripping the pliers and poking the fibers through will start to hurt after an hour or two. (The Mk II hole poker, with the needle taped to one jaw, the jaws taped shut, and the handles squeezed together and similarly taped is very handy)
Eventually, you should have placed every fiber into your star map. Take a deep breath, and relax. It's quite pretty, even viewed from the back.
Step 15: Secondary Light Sources - Planning
To light the brighter and constellation stars, it works well to use individual LEDs. These need to be driven by a power supply of their own, as the LED spotlight I use only has an internal power supply. I had an old printer power supply that supplied 30V, 400mA. This is ideal, as the high voltage allows me to drive multiple LEDs in series.
This next bit is somewhat technical. If you aren't confident with LED circuits, consider reviewing some of the simpler LED-based instructables on this site, or consider whether it would be appropriate to use LED Christmas lights instead.
For a given power supply voltage, you can run up to N LEDs in series, where N*forward-voltage-drop is less than the that voltage. At full brightness, the LEDs I used have a forward voltage drop of 3.15V. If I have a 30V power supply, I can run up to 9 LEDs in series with a small ballast resistor. (Don't forget though, in most cases a ballast resistor will still be needed)
For a given power supply amperage, you can run up to M LED chains in parallel, where the current through one LED * M is less than the power supply amperage. If I have a 400mA power supply, I can run up to 20 chains of LEDs. (In practice though, you don't want to have a power supply running at its maximum capacity in an enclosed space for long periods of time - the lifetime of the power supply will be reduced.)
Count the number of brighter stars on your map. In my case, there were 108 constellation stars. Inside the space of possible LED array arrangements, I chose to have 12 chains of 9 LEDs.
If you have a large number of LEDs to power, it may help to build a junction board. This simple circuit board splits the 30VDC supply into 12 sockets, each with an appropriately-sized ballast resistor. It makes wiring much easier!
Step 16: Secondary Light Sources - Planning II
As the schematic below shows, a potentiometer controls the voltage, and thus the amount of current flowing into the base of an NPN transistor. The transistor then allows a proportional amount of current to flow across it, thus controlling the brightness of any LEDs attached. My test circuit was controlling a single LED from a 5V source, but the principle for 108 LEDs was exactly the same; just connect the negative ends of the LEDs/resistor chains to the transistor, instead of straight to ground.
Choose a transistor able to cope with plenty of power, and attach a heatsink.
As poster Fake_Name mentioned, there are many different ways to regulate the current flowing through the LEDs. This circuit is not the most efficient solution, but it is one of the simplest. Other features you might like to investigate:
* automatic brightness adjustment for the ambient light (using a photocell or LDR),
* auto-off (a valuable feature if your star map runs on batteries)
* individual LED control (overkill sure, but you could make them actually twinkle)
* RGB LEDs (purple and green stars, why not?)
Step 17: Secondary Light Sources - Assembling Light Pipes
Put together a pile of as many LEDs as you'll need, a pile of 2cm-lengths of heat-shrink large enough to go over an LED, and a pile of 2.5cm-lengths of acrylic rod. (You can quite easily cut the rod with a good pair of side-cutters)
Assemble the LED, heat-shrink and acrylic rod together, then using a soldering iron or a heat gun shrink them together. Try to avoid getting the LED too hot, as it can kill them. Repeat until you have a hundred or so of these assemblies. (This is, believe it or not, another step that takes a long time.)
Note: I initially tried melting acrylic rod directly onto the LED. The LED is a different type of plastic so the rod does not 'stick' properly, the acrylic starts to darken when it is heated, and lots of noxious gases are produced. Not recommended.
Step 18: Secondary Light Sources - Installing
For your array layout (in my case, 12 chains of 9), plan the best way to wire up your chains. Then, carefully solder each LED in a chain together, from the shorter negative lead of the previous LED to the longer positive lead of the next. At the ends of each chain, there should be a clearly indicated red (positive) and black (negative) end, and ideally have some sort of keyed connector back to the junction board to make life easier.
At this stage, you should test your LED chains to make sure all the LEDs work, and are connected the right way around. *cough* Ease of access is one reason it is better to wire in the secondary light sources before you put the optical fibers through. The other reason is that optic fibers are made of thin filaments of plastic, and tend to melt right through at the slightest touch from a soldering iron, so keep them well apart from one another.
Once everything is working, apply some wood glue around the outside of each LED assembly to keep them in place, and make the connections neat
Step 19: Narcissism
These LEDs are connected into the same 30V power supply as the other secondary light sources. The circuit is simply three LEDs in series with an appropriate ballast resistor, soldered to a small piece of veroboard.
Step 20: Trimming
Turn the frame around so you can access the other side. If your working area is carpeted, put down some newspaper. (Trust me, I'm still finding stray fibers stuck in the carpet)
With a pair of side cutters, cut off every fiber and light pipe so that only about 2-3mm is still poking through the front of the substrate. You don't want to cut it completely flush, or the fiber might pop back through the fabric.
This stage is disappointingly much quicker than placing all the fibers. When finished, gather up and dispose of the thousands of short fibers you have cut. (I tried to think of a use for them, but other than those in the signature I only ended up using one as a cat-taunting toy)
Step 21: Wiring
As a bonus, the switch module has two channels, so another AC circuit can be controlled, up to 500W.
The top-level schematic shows how all the components of the system are connected.
WARNING:A good portion of the wiring is at mains voltage and can be very dangerous. If you don't know what you're doing, don't. Even if you think you know what you're doing, make sure that the outlet you are using is protected by an RCD (Residual Current Device, also known as a Ground Fault Circuit Interrupter). Do not lick wires.
Commenter static asked why an RCD on the outlet's circuit would be necessary for a device like the star map - because if while you are wiring it up you accidentally do something stupid it's better to have the RCD trip and say to yourself "I just did something stupid" than to risk electrocution.
The switch module and power supply should be placed inside the edges of the frame, and secured with screws and wire as appropriate. Ensure that the power cables have some kind of strain relief, and if possible use a terminal block with an insulating cover.
Step 22: Putting It All Together
Next, staple more black cloth to the back of the frame to block out any light leakage, and to protect the fibers and electronics.
Step 23: Hanging Around
Put two long screws into the top edge of the inner frame, and put some fairly heavy-duty wire between them. Hang the frame up on the wall, do not knock any ornaments over in the process, plug it in, and done!
Step 24: Bask in the Glow
(That second RF switch channel? It runs the lava lamps on either side of the star map)
Step 25: Addenda
Using 2mm LEDs as 'Stars' in corrugated cardboard substrate:
If you want to use 2mm LEDs, the round section tends to be quite short, and may not fit all the way through a substrate. A good way to mount these LEDs into cardboard is shown in the first diagram; by drilling a 2mm hole, then cutting a small slot across the back of it (only cutting through the back face of the cardboard), the LED can be pushed through into the substrate itself with only the tip of the LED poking through to the other side. Perfect! (This works really well, and is by no coincidence the method my Star Map MkII uses)
Making the stars flicker
When you watch a fiber-optic tree or UFO Lamp, the fibers tend to change colors. This is a cool effect, and something that you could either use as-is, or modify slightly to have the stars change brightness rather than color. As the second diagram shows, a problem is that the color wheel inside the base needs to be quite large, and may increase the depth of the star map significantly. A possible solution might be to construct a 'color belt' instead of a color wheel (see third diagram), this would allow you to keep the depth relatively shallow, and the only increase in depth would be the motor body.
Commenter frollard had an even better design for flattening the color/flicker mechanism - see his diagram in the comments.
To have the large stars flicker, you may be able to use 'flickering' Christmas lights, or go all-out on the electronics side, make the LEDs individually controllable, and implement a multiplexing function that can display multiple levels of brightness.
Take care with your fibers. If they are bent too sharply they will craze, and light will spilled out in the wrong place. If done carefully, you may be able to intentionally use this property to make stars of different brightnesses.
Multi-Sourced Star Map
As commenter AlphaRomeo suggested, one way of having multiple levels of brightness could be to have multiple trees/lamps in the same area. Bright stars might use fibers from tree A, medium stars from tree B, and faint stars from tree C... and each tree could have the brightness of the light source set appropriately.
I think this would look fantastic, but it would probably be very difficult to accomplish without getting everything tangled up.
Step 26: Addenda - Smaller Star Maps
For smaller star maps, there's not much room for a light source. This is one fairly simple approach that works well.
First, find an aerosol/bottle cap that snugly fits over the terminator. This one was misappropriated from a bottle of the wife's hand cream. Figure out how many of your LEDs will fit in it, and drill holes so that the body of the LED fits through, but the flange of the LED does not. A tight fit and a little glue will keep them in.
Next, (for parallel wiring) insert all of the LEDs with the shorter negative end in the center. Tie these ends together and solder. To each of the longer positive ends, solder an appropriate resistor, and cover with heatshrink to electrically isolate them.
I have linked opposite LEDs together into three channels and soldered them to a protoboard. Each pair of LEDs is controlled by a microcontroller pin.
Step 27: Addenda - Smaller Star Maps II
One problem that arises when placing fibers is preventing them from kinking. It's very easy to bump the fibers that have already been placed. I have found the following method to be very helpful in keeping the fibers safe.
For the substrate, find a piece of cardboard that is much larger than needed, particularly on the sides. Score (rather than cutting right through) the sides of the map, and glue the mirrored pattern on the back. Then, score the cardboard to either side of the map, and bend the side down to make a small 'table'. Small corners of cardboard and tape will keep the sides in place. This way, the map is held up off any surfaces and the fibers are less likely to be damaged. When you are ready to mount the map in its frame, you can finish cutting through the sides.
Painting the Front of the Substrate
This is an important point, that was found out the hard way. Oil-based paint dissolves plastic fibers! Many ceiling installations recommend painting over the fibers before trimming them, but if you use oil-based paint you render all your hard work useless.
Either use water-based paint or paint your substrate before placing fibers.
If using the "table" holding method described above, it's quite easy to paint the substrate before the fibers are placed.