``As a grown man, this is good stress relief and it keeps my imagination going,'' said Stangl, a 34-year-old technical support engineer for Sun-Netscape Alliance and one of thousands of techies taken with this children's toy.

The Silicon Valley's fascination with the famed Danish interlocking plastic blocks took off in the fall of 1998, when Lego launched Lego Mindstorms - a new generation of Legos that could be manipulated using microcomputers, light and touch sensors, an infrared transmitter and CD ROMs.

Computer programmers quickly hacked the Mindstorms' code and began devising ever-more complex creations: a miniature photocopier, a coin sorter and a variety of robots that can bark like dogs, climb stairs or carry the morning paper.

Programmers have figured out how to control them with everything from their CD players to Palm handheld devices.

``A lot of kids get rid of their Legos when they're teen-agers. But a friend got me back into them and I'm really having a good time,'' said Stangl, a member of the Bay Area Lego Users Group, which corresponds online and meets monthly for building sessions.

Lego Mindstorms Vice President Linda Dalton, who works with master builders at the company's colorful Novato, Calif., headquarters, said adult buyers boosted sales 300 percent last year.

``We thought these were going to be for kids, but what we're seeing is a huge amount of interest from the high tech community,'' she said.

Engineering teachers around the country are introducing the toys to their students for projects.

``There is something very exciting about making physical objects come alive,'' said Mitchel Resnick, an assistant professor at the Massachusetts Institute of Technology, where he uses Mindstorms to teach students in his media laboratory.

``In the past, you had to be a technical wizard, buying parts from Radio Shack, to build your own robot, or to add a sensor to the door of your room. Lego Mindstorms makes it possible for a much larger community of people to create their own computerized contraptions - and the sales figures demonstrate that many adults are interested.''

Indeed, Lego officials in Copenhagen credit the Mindstorms line with the company's financial recovery.

Last month, Lego chief executive Kjeld Kirk Kristiansen - grandson of the company's founder - said 1999 ``began in insecurity and nervousness but ended with progress and belief in the future.''

The company said it lost money in 1998 for the first time since it was founded in the 1930s because of increasing competition from electronic toys and computer games.

But about 80,000 of the $200 Mindstorms kits sold in the first three months they were on the market, and their continued success has pulled the company back into the black. The company hasn't released Lego sales figures since.

``We still have a long way to go before our cultural transformation is complete, but the trend has been reversed and the clouds are lifting,'' Kirk Kristiansen said.

By MARTHA MENDOZA, AP Business Writer

[Updated 3/27/2000]