Posts tagged crystal ball lamp
Crystal Ball Lamp, part 3
Nov 20th
—— The Electronics ——
In this post I’ll discuss the design of the electronics part of the Crystal Ball Lamp.
The lamp is controlled by an Arduino Mega microcontroller board. I was originally going to use a less expensive Arduino Pro Mini. It doesn’t provide enough PWM outputs for the nine LED channels I wanted to control, but I could do some multiplexing to get an approximate PWM signal to each of the channels independently; it would complicate the circuitry, but I could endure that if it saved enough money. As I worked through the design, I began to get concerned about the small amount of RAM available on the ATmega328 used by the Pro Mini (2 KB), fearing that this would not be enough to run my lightshow programs for nine channels and be able to run a scaled-down graphical-user-interface through the oLED display (mostly just menus that a user scrolls through). Furthermore, the Pro Mini only has one hardware serial port. I wanted to communicate with two serial devices – the XBee module and the oLED display – so with the Pro Mini one would have to be handled through software, which would use even more RAM and slow down the performance of the whole device. So with all these concerns, I just went ahead and splurged on the Arduino Mega. It had more than enough PWM outputs for my nine channels, more RAM (8 KB), and more than enough hardware serial ports.
Crystal Ball Lamp, part 2
Nov 18th
—— The Materials ——
This post will be fairly short, but hopefully will answer some of the questions I’ve received about where I got my materials.
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- wood
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- aluminum sheets
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- LEDs, heatsinks, and lens
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- circuit boards
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- LED drivers
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- ribbon
The pictures above show what some of the raw materials look like. The list below tells where I got them:
Crystal Ball Lamp, part 1
Nov 17th
I purchased some high-powered RGB LEDs from Sparkfun Electronics mostly because I wanted to play with them enough to learn how to use them, but also because I thought I might use them in a chandelier I’m going to make to hang over my dinette table. As I played with them, I realized that they wouldn’t be all that good for my dinette chandelier for a couple reasons:
- While the three colors combine to make something that looks like white light to our eyes, it’s not really white light. The combined spectrum of the RGB LEDs is very spiky, with narrow bands around the red, green, and blue parts of the spectrum and not much in between. This causes food (and other things) to look weirdly discolored when lit with this kind of light.
- The LEDs on Sparkfun’s circuit boards are spaced far enough from each other that the objects casting shadows cast three differently colored shadows. I actually like how this looks, but I decided it would get annoying as the main light source for a table that I use regularly.
After playing around a bunch with the LEDs, I somehow managed not to fry any of them, so then I had some spare LEDs without a destiny. Time to have some fun … 
I’ve been wanting some kind of decorative lamp in my hallway, so a new project was born. This article is just an introduction – I’ll explain the project in more detail in later posts. More >
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