Homemade Infrared LED Pen for use with Wiimote projects

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Purpose:

This project was inspired by an article Johnny Chung Lee wrote on using a Wii remote (Wiimote) as a IR position receiving device for use in a home-brew electronic whiteboard.

The Wiimote contains several technologies which make it a nice little device for IR point detection. The Wiimote contains an infrared camera that detects an infrared point and relays it's coordinates back to the PC. It also has sensors for relaying its position in space (roll, yaw, etc.), rumble, speaker and buttons for emulating mouse clicks.

This article has three parts.

• Building the IR pen for use with the Wiimote.
• How to connect your PC to the Wiimote.
• Applications for utilizing the Wiimote on the PC

Building an Infrared Pen

An IR Pen is relatively easy and inexpensive to build. It is comprised of an IR LED, switch, battery pack and a pen housing. All parts except the pen were purchased from Radio Shack.

Parts

Procedure:

Below is a diagram and parts showing the schematic of the IR Pen components:

The IR LED positive terminal is the longer/flat wire. It is connected to one terminal of the switch and the other to the positive wire of the battery holder. The other terminal of the LED connects to the negative terminal of the battery holder. A resistor isn't needed since we are using a 1.5V power supply.

The pen was disassembled and the rubber boot removed. The boot covers a plastic tube which then connect to the blue tube of the pen. A large hole was drilled in the bottom of the tube and a small hole was drilled for the pushbutton to protrude. When the rubber boot is reinstalled, it will protect the soldered contacts on the switch (positive terminals).

The negative terminal wire was fed through the tube as well. A Motherboard LED connector (2 pin female) was used to attach to the LED,which allows easy LED removal in case the LED burns out or gets damaged.

The removable tip of the pen secures the LED and allows a nice clean look. I cut the tapered end of the tip off to allow the LED full illumination. The positive and negative connections were fed out of the back of the pen to the small battery pack.

The pen can be easily handled with the battery pack tail dangling.

In order to test the IR pen, a digital camera is used. The digital camera is sensitive to infrared light and will show the glow which is invisible to human vision.

Conclusion:

The IR pen cost less than $10 to make and worked very well. The pen was successfully used with the Wiimote and test software.

Page 2: Connecting your Wiimote to your PC

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