Difficulty Level = 6 [What's this?]

Arduino Mood Lamp

This is a mood lamp I build using 16 LEDs of different colors and small glass vials. The square bottoms of the vials look a lot like glass block, and the glass diffuses and scatters the light in beautiful ways. The software shows random patterns of light and the brightness of each LED can vary — they aren’t simply “on” or “off”.

The Arduino code is pretty complex because it implements PWM (pulse-width modulation) for all 16 LEDs. The Arduino board only has 5 PWM-capable pins, so providing PWM for all 16 pins is accomplished purely in the code. The lamp randomly displays different lighting patterns and can be really mesmerizing. Ok, I know you want to see it in action, so here it is (note that the music is just in the background — the lights are not reacting to it):

Construction

The base of the lamp is a piece of plexiglass about 5 inches square, and all of the wiring is on the underside of the plexi. Each of the 16 LEDs goes into a small socket made from two pins of a female header. I used sockets instead of soldering the LEDs directly so that I could rearrange the colors any way I like.

LED sockets

Difficulty Level = 6 [What's this?]

After tearing down an old CD player, I was inspired by the CD laser scanning assembly to build a door lock for my subterranean lab. The assembly has two motors: one for turning the CD (I’m not using this one) and one for slowly moving the laser across the CD’s surface. This second motor provides a nice linear motion that I wanted to use to build an electronically-controlled dead bolt lock for my lab.

Here’s the assembled lock. The circuit board in the middle is an H-bridge circuit I built to allow the motor to move in both directions. There are two position sensing switches so the Arduino senses when the motor has reached its limit in either direction. A 9V power supply powers the Arduino board, and a separate 5V supply drives the motor through the H-bridge. The dead bolt is literally a bolt — connected to the assembly with a piece of scrap circuit board — that travels through the door jamb and into the door.

The lock in the closed (locked) position.

The black CAT5 cable connected to pins 2-8 goes through a small hole in the wall (under a desk) to the keypad on the outside of the lab (I wasn’t sure I wanted to permanently mount the keypad in the wall). The user types in the correct code and presses the # key to open or close the lock. The green LED indicates the door is unlocked. Red indicates locked.

Lock keypad - green indicates that it's unlocked, red indicates locked.

Let’s see the lock in action. (While recording, I gave instructions to my son to lock and unlock using the keypad off camera.)

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