Introduction: Nighttime Planetarium
I made this project right before my son was born, with the intention of creating a fun, comforting nightlight that had significance for him. The concept is pretty simple: A wooden box with an LED inside that projects light onto the ceiling through a dome with holes cut out in the pattern of stars in the night sky. The box also opens up and there are a couple of compartments in there for various treasures. I downloaded a star chart for my son's due date to make the star pattern on the dome. (He was born a little earlier than the due date but it is still pretty close!)
To make this project you will need:
- 1/4" plywood for top and bottom
- 6 pieces of craft wood from Michael's or other hobby shop for the sides and dividers inside
- small wood block (approx. 2" x 3")
- 4 corner braces
- wood glue
- 2 brass hinges
- brass latch
- 3 quart stainless steel mixing bowl
- adhesive Velcro strips
- section of rubber garage door seal like this
- black spray paint
- wood sealer/varnish
- scratch awl (to make the stars)
- 5mm white LED
- 22-gauge wire
- 4-AA battery holder
- Toggle switch
- perf board
- 220-ohm resistor
- solder and soldering iron (OPTIONAL)
Step 1: Build the Box
The 10"-square box construction is very simple: 4 pieces of craft wood (about 10"x3"x1/2") glued in a square. I reinforced the corners with small corner braces. I think these technically are supposed to go on the inside of the corner, but I thought they looked kind of industrial-decorative on the outside.
The bottom piece of 1/4" plywood is cut to fit inside the box frame, then glued into place. I hammered in a couple of tacks as well just for extra solidity. The 1/4" plywood for the lid is a little larger than the bottom piece since it fits over the top of the box (rather than inside the borders).
I traced a circle around the outside of the 3-quart mixing bowl, and cut a hole in the lid that was about 1" INSIDE the outer perimeter. That way there is wood there to secure the bowl to the lid with screws. More on the bowl in the next step.
I also made a hole that would fit my on/off toggle switch on the side of the box. This is so the switch could be in the center, and then the front side has a latch in the center of the front panel.
The inside of the box (and the bowl) should be painted black, so the LED's light doesn't reflect all over the place in there before going out to your ceiling. I recommend spray painting the pieces (inside of the box, inside of the lid, and inside of the bowl) before finishing the outside of the box. That way any stray paint blobs can be sanded off before putting the varnish on it.
I added a bunch of fun space-themed stickers on the outside and bottom of the box. I also signed the bottom and put a few personal touches on there. Then I put 3 coats of polyurethane coating on the outside of the box, sanding lightly between coats.
The lid is attached to the box with 2 nice brass hinges. I also put a little hook latch on the front.
Step 2: The Dome
The planetarium "dome" is a 3-quart stainless steel mixing bowl. It should have a little flat lip at the top so there is some way to screw it to the top of the box. Paint the inside of the bowl matte black. If you leave it shiny the light will bounce around inside and you could get weird multi-stars. You don't want that.
To make the stars, I printed out a star chart from the Web (I used telescope.com). Print it large enough so it can drape over the whole surface of the bowl, an 11x17 sheet works nicely. (Use the office printer!) Tape the paper over the surface of the upside down bowl so you have a template for where to punch the holes. Punch right through the paper into the bowl. One trick I used was to clamp a dowel to my sawhorse, then hammered the awl through the bowl into the end of the dowel. (See photo with tasty beer). That way you don't cave in the surface of the bowl when you hit it.
I basically did the major constellations, the planets, the moon, and then added a few random stars just for depth. The planet holes are about 1/4" diameter, then the constellation holes are about 1/8" and the background stars are just pinpricks really. Just pound the awl into the bowl more or less to get the different size holes (the awl is tapered). For the moon, I made 3 holes in a rough crescent shape. There must be a tool you can use to make a nice crescent moon-shaped hole, but I don't have it (yet!).
After you have made your holes, remove the paper and, using the chart as a guide, draw lines that connect up the constellations with a Sharpie. You can also mark the planets and the moon. You can label everything if you want but I just made the shapes and left off the labels.
Punch a hole on each of the 4 cardinal directions in the lip of the bowl, and screw it down over the hole in the top of the lid.
One extra step I took was to make a seal around the hole on the inside of the box. I cut a length of rubber garage door weather stripping (the stuff that goes on the bottom of the garage door) and glued it in a circle inside the hole. It fit nicely in there and the seal extends up into the bowl a little. The point here is to make it so you are not losing any light out of the space where the bowl meets the wooden lid. I suppose you could caulk it as well.
Step 3: Circuit
This is a very simple circuit. You have a toggle switch, a battery pack (4 AAs), a 220 ohm resistor, and a 5mm LED. I put the LED into a perf board from Radio Shack (I think I sourced everything from there).
The way it is wired up in the photo is a little weird, but basically you need to connect the positive (red) wire from the battery pack to the positive side (longer leg) of the LED, then connect the negative leg of the LED to the resistor, then the negative wire goes from the resistor to one of the tabs on the switch. Connect the black wire from the battery pack to the other tab on the switch.
The other part of this was to put in a small wood block in the middle of the box, in order to raise up the LED to the point where it was shining upwards, above the rubber inside the lid. This way light does not escape out of the gap between the lid and the box. I attached the perf board to the wooden block with some adhesive Velcro strips.
Note that it would be smarter to solder everything together, but I did not do that here. I just twisted the wires around each other, since I did not have a soldering iron and at the time I thought it was a difficult thing to do (it is not).
The final step is to stick the switch out of the hole in the box, screw it down and turn it on!
The effect is what I would call charming. It's not a super bright, realistic, virtual star map, it is more like a nice, comforting starry night effect. However, it is quite nice.
Last tip: I would advise using rechargeable batteries, because if you use it as a nightlight, it will last a couple of weeks but then the batteries will be drained.
OK that's it! Hope you enjoyed this Instructable. Thanks for reading!
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