LED Planetarium

Introduction: LED Planetarium

Design of this LED Planetarium allows you to mimic a starry and beautiful night sky within the comfort of your own room. Using a few electrical components and household / cheaply bought materials I was able to successfully build this device as a thoughtful present with excellent results. Unfortunately I do not have a recording of this being used to full effect.

Credits to https://www.instructables.com/id/How-to-build-an-LED-Planetarium/?ALLSTEPS as my main resource of assistance.

Step 1: Components and Tools Required

Feel free to substitute anything that you feel will work just as well

Electrical Components:
3W Violet LED
Toggle Switch
4 AAA batteries
Battery Holders
Resistor (Refer to section just below for specifications)
Resistor in this picture is incorrect
Heat Sink

I chose Violet as that is the favorite color of my friend. Any color should work as per liking, although white would be the most accurate representation, of course, of a night sky.
NOTE: Only one LED may be used or else more than one projection hole will appear.

Resistor Calculations:
I had used this.
Source Voltage: 6V (4 AAA batteries at 1.5 V each -> 1.5 x 4 = 6)
Diode Forward Voltage: 3.6 V (According to the specifications listed (3.2 - 3.6 V): we choose the higher)
Diode Forward Current (mA): 700 mA (According to the specifications listed)
My resulting Resistor: 3.9 ohms, 1.9 W capable
I had purchased this which is 3.9 ohms and 25 W capable.

Heat Sink
For safety, I had used a spare Heat Sink I had lying around for when I would use my Arduino.

Plastic Case Bowl
Plastic Dome Bowl
Grip Shelf Liner
Small Wood Board
Non-Gloss Black Spray Paint (applicable to plastic)
Sturdy Paper (Resumé paper)
Constellation Map (Original)
Constellation Map (Version I Used)

Wooden Board
The small wooden board is unnecessary if you are able to find a bowl that fits perfectly on top of the case bowl. I used the wooden board a stable surface to hold the dome bowl.

Non-Gloss Black Spray Paint
Non-Gloss Black Spray Paint is used to prevent light from escaping and/or reflecting.

Soldering Kit
Sharp Tool (to poke holes)
Wire Clipper
Elmer's Glue
Thermal Paste

I had used this kit. Be sure to watch a video on how to solder if you are not sure how to. I covered my work station with paper towels when soldering (as you will see in the pictures).

Sharp Tool
After searching through my father's toolbox I was fortunate to find this tool which saved me the trouble of having to hammer a thin nail continuously for every single hole. Image

Thermal Paste
I am not certain how required it is to use thermal paste but I had some lying around as I recently built a new computer. I suppose if I did not have thermal paste I would have to look into using screws to keep the LED locked in place.

Step 2: Preparations & Painting

With all the materials in possession, before getting to the electrical components everything else must be set up. Keep in mind you want to spray paint last as painting then making the holes will cause the paint to chip off (I now know this from experience).

Preparations involve (feel free to do this in any order before painting):

  • Cutting a circle of resumé paper that is the diameter of the Plastic Dome Bowl to fit flat over the wood board.
  • Cutting a circle of grip shelf lining to fit flat over the Plastic Dome Bowl paper cut out.
  • Cutting a circle of grip shelf lining to fit flat on the inside of the Plastic Base Bowl. Image
  • Cutting the shape of the heatsink out of the grip shelf lining. Image
  • Cutting a wooden board (or equivalent sturdy surface) a little wider than the diameter of the Plastic Dome Bowl. Image
  • Placing the shelf liner cut out (size of the Plastic Dome Bowl) on top of the circle cut out and gluing the circle cut out on top of the wooden board.
  • Cutting two holes in the wooden board for wires to go through.
  • To do this center the shelf lining cut out meant for the Plastic Dome Bowl on the wooden board. Using the part cut out for the heat sink as measurement, space out the two holes meant for the wires and use the hole-making tool to poke holes through the shelf lining and the wooden board. Image
  • Poking a hole in the Plastic Base Bowl with your hole-making tool and placing the toggle switch oriented appropriately to your liking (mine is switched up for ON and down for OFF pictured here).
    Don't leave the Toggle Switch when painting.
    NOTE: You want the holes to be extremely thin such that the metal of circuit wire just perfectly fits through the hole.
  • Printing out the constellation map, resizing it to fit your bowl, and taping it down over the Plastic Dome Bowl.
    For resizing, I placed a blank piece of paper over my Dome Bowl and taped down all four sides. I then marked where the ends of the bowl touched all four sides and used that as a rough measurement for sizing my constellation map.
  • Poking all the holes into the Plastic Dome Bowl with the constellation map taped down. Image

With all the preparations complete, set up some newspaper and paint all the materials. Black paint is used to prevent light from escaping and/or reflecting. Image 1Image 2

Step 3: Assembly of the Planetarium & Circuit

With the painting finished it is now time to assemble the electrical circuit:

Image (Credits to mattthegamer463 for the image)
NOTE: Your values may differ from this image, the voltage (V1) I used was 6 V and the resistance (R1) was 3.9 ohms. Please refer to the 'Resistor Calculations' section in Step 1 on how to find the value of you resistance. For voltage, each AAA battery is 1.5 V, I used four AAA batteries to have 6 V.

Before beginning, the placement of the overall project is as follows (reference Image 2 below):

  1. Have the Plastic Case Bowl placed flat on a surface, with the opening facing up.
  2. Place the shelf liner cut out inside. The battery and resistor will be placed in this bowl.
  3. Place the wooden board on top of the Plastic Case Bowl.
  4. Place the paper circle cut out on top of the wooden board that is the diameter of the opening of the Plastic Dome Bowl.
  5. Place the shelf liner cut out on top of the paper circle cut out that too is the diameter of the opening of the Plastic Dome Bowl.
  6. Place the Heat Sink in the center where a cut out space was made on the shelf liner.
  7. Place the LED on top of the Heat Sink.
  8. Place the Plastic Dome Bowl upside down to perfectly fit on top of the paper and shelf liner.

For a "cleaner" picture of this setup:
Again, credits to mattthegamer463 for the Image.

Begin with your battery holder: Image 1Image 2
As seen in Image 1, the four batteries are placed with the appropriate respective polarities. As seen in this Image make sure batteries make contact and are securely placed.

  • With the batteries in place and as shown in the circuit diagram, hook the ground (black) wire to the middle terminal of the switch (if yours is a three terminal). Ensure that contact is made between the wire and terminal.
  • Take another wire (to be soldered to the negative of the LED) and connect it to an adjacent terminal and place it through a hole of the wooden board.
  • Next, with the power (red) wire from the battery holder, make a secure connection to the resistor.
  • Take another wire and connect it to the other end of the resistor and place that wire end through the other hole of the wooden board.

Next, take the Heat Sink and apply thermal paste to the bottom and place it on the cut out paper (with space reserved on the shelf lining). Apply thermal paste to the bottom of the LED and place it on top of the heat sink.

With everything set, it is time to solder the connections together.

Step 4: Soldering

BEFORE soldering ensure that the circuit properly works. Make sure all the connections are tight and make contact with each other and with the two wires in hand, to be connected to the anode (positive) and cathode (negative), have them touch their corresponding polarity and the LED should light (make sure the switch is turned to ON).
Refer to the video at the very top of the page for the LED lighting up!

For a video on how to solder refer to the embedded instructional video

Solder all the wires together and ensure that there is a good connection between the respective wires and terminals.
NOTE: To be safe make sure the switch is turned OFF.

  • Solder the ground (black) wire of the battery holder to the middle terminal of the switch.
  • Solder a separate wire end to an adjacent terminal of the switch.
  • Solder that separate wire to the negative (Cathode) terminal of the LED.
  • Solder the power (red) wire of the battery holder to the resistor.
  • Solder the other end of the resistor to a separate wire.
  • Solder that separate wire to the positive (Anode) terminal of the LED.

Place the dome over the base bowl and flip the switch to ON. Unfortunately I do not have footage of the Planetarium in use. Please let me know in the comments section or e-mail me at cbonjoc@gmail.com if you happen to have any question or comments.

Enjoy your own LED Planetarium!

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    Cool. I know that my kids would love to have one of these in their rooms.