Baby’s First Star Light Projector And A Foil Slip Ring

For a newborn, everything is magical; a lack of object permanence means everything is new, wonderful, and novel. What then, could be better than a projected star field circling an infant’s room, gently sending them to sleep?

[Pete] was inspired by this earlier starlight projector that projects a rotating star field onto the walls and ceiling of a nursery. Instead of a rather loud servo, [Pete] used a quiet 12 Volt gear motor that spins the star field at 5 RPM. Like the previous build, a LED was used but [Pete] found a color-changing RGB LED that automatically shifts colors.

The shaft of [Pete]’s gear motor is tiny, and unlike the servo, there’s constant rotation. This meant a slip ring was needed to pass electricity into the spinning sphere. A piece of copper foil and a pair of improvised brushes served just fine. While [Pete]’s project, like its predecessor, doesn’t seem to have any recognized constellations drilled into the sphere, the foil slip ring opens up the possibility for a small microcontroller being fitted inside the globe with blinking lights.

Check out the video of [Pete]’s build in action after the break.


7 thoughts on “Baby’s First Star Light Projector And A Foil Slip Ring

  1. Why on earth did he need a slip right for this?

    1. Use a 3-color LED or plce all 3 LEDs in a central location, facing up so as to converge

    2. Create an axle around the LED(s)

    3. Put a hole in the ping pong ball (to fit on the axle)

    4. Rotate the ping pong ball on the axle containing the LEDs using a rubber wheel, or carriage arrangement of 3 wheels (one being attached to the motor, the others as bearings)

    But the slip ring is well done :)

  2. I recall reading an article recently that said, basically, that infants may not remember what they saw, but they remember that they’ve seen something ‘like that’ before. :)

    I always loved the fluorescent stars my parents had painted on the ceiling at my childhood home, complete with the handprints in the milky way where I rubbed off some of the fine spray they used.

  3. 5rpm seems fast to me. Anyway, Perhaps it would be fun to make one that mimics the night sky. Not just constellations but speed and tilt as well. Ignoring unfun specifics like central location in a room and corner distortion and other pedantic crap.

  4. I like your project and I like the slip ring because it simplifies the mechanics of the operation. A well done project.

    For future reference the 7805 is not necessary. Kirchhoff’s law of voltages states that the some of all voltage drops equals the source voltage. which means that you need only select the correct resister to power the led from your twelve volt source. If calculating the LEDs forward voltage drop against a given resistance is confusing then try a web based calculator like (

    I hope this info makes your future projects quicker, cheaper and easier.

  5. Wizzard: I’d love to see a functioning version of what you described above.

    tinkermonkey: I know, the 7805 was not -needed-, but I knew for sure I had a 100 Ohm resistor in my box-o-parts. At $.50, so I just went with it.

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