David Jones really liked his old Casio CFX-400 scientific calculator watch. As a professional electronics design engineer, he appreciated the greater functionality it had over other calculator watches, which typically support only the four basic functions. He was saddened when his 20-year-old Casio finally bit the dust, so when he looked around and realized there was no one making scientific calculator watches anymore, he decided to make his own.

He calls it the μ Watch (“Micro Watch”). His goals were to make a scientific calculator watch that was good-looking and practical, and could be assembled from off-the-shelf parts.

“I could have designed a custom case for it, and used custom parts to get the size down and make it look like a store-bought watch, but there was no fun in that! Using off-the-shelf parts was a real challenge and in the end was the most satisfying aspect of the project,” Jones recalls.

A resident of Sydney, Jones has been publishing projects in Australian electronics magazines since he was 15. Besides his μ Watch, he’s designed and built his own solar air heater called the Solar Sponge, and written an interactive exercise program that runs on iPods and other MP3 players. He also likes to get involved with serious home renovation projects.

Jones has released his μ Watch source code under the GPL to encourage third-party development, and he sells kits for those interested in building one. He includes a complete schematic and detailed photos on his website.

And the μ Watch isn’t limited to being just a scientific calculator. Its programming port, universal I/O port, and optional infrared remote interface let you connect it to almost anything. “With the two-line LCD, full keypad, and 16-bit microprocessor, it’s really a powerful general-purpose computing and control platform,” Jones points out.

If you want a μ Watch that controls your TV, plays games, or commands other user-designed devices, just add some software. –Bruce Stewart, Made on Earth MAKE volume 15 page 20.