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Project Notes

#338 GlowBall

Building LED effects for a Glass Eye Studio Celestial Planet Weight.

Here’s is a video with a few soothing minutes of the glow effect;-)

Build

Notes

This Glass Eye Studio “Celestial Super Nova” was a gift. Quite an awesome piece of glass work … I have no idea how these can be manufactured in any quantity with consistency! Perhaps I should find a class?!

You can buy a base with built-in lighting effects, but where is the fun in that?

Here’s a project to make a base for the glass ball. Because it is going to be used on a desk, I decided to combine two functions:

  • a multi-colour “glow” effect to light the ball
  • or switch to power a 3528 LED strip (1m, 60 LEDs, 12V, cold white)

GlowBall_build2

Case Construction

I found an old iPhone earbud case which makes a perfect housing.

GlowBall_internals

I pulled a bit of black cushion padding from another box to fill the clear box case while allowing the LEDs to poke through to light the glass ball:

GlowBall_case_front

LED strip plugs in on the left, power on the right:

GlowBall_case_rear

Circuit Construction

The electronics are a combination of circuits (with some modifications) from two projects:

I’ve set this up powered from 12V. A three-position SPDT switch selects between: off, the glow ball effect, and powering the LED strip.

Key notes on the RGB LED Glow circuit:

  • I’ve intentionally got the PNP driver transistors in back-to-front (C and E flipped). The transistors work, but just not as well. In this context, that is a good thing, because it creates an expanded “linear” region and very nice glow effects (I think). Current is not so high, hence the current-limiting resistors (360Ω) are lower than you might expect for 12V.
  • the three triangle-wave oscillators are nominally identical, but component tolerances lead to the slight variation in performance which causes the red, green and blue LED poles to oscillate just slightly out of sync.
  • the wave-offset adjustment pot (VR1) is a trimmer that I haven’t exposed for external adjustment. I just set-and-forget it to a nice value for best effect.

Key notes on the LED Strip circuit:

  • I’m using a 1N5711 instead of a 1N5819 because it was available. It is not carrying any real load so the most important feature is the similar forward voltage.
  • the dimmer pot is the one mounted on the front of the case

Schematic

Breadboard

FWIW, here are my scratchy notes on how I laid out the protoboard:

GlowBall_board_layout

GlowBall_build

Credits and References

About LEAP#338 LEDOscillatorsPowerCraft

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

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About LEAP

LEAP is my personal collection of electronics projects - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting.

Projects are often inspired by things found wild on the net, or ideas from the many great electronics podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know or send a pull-request.

NOTE: For a while I included various scale modelling projects here too, but I've now split them off into a new repository: check out LittleModelArt if you are looking for these projects.

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