In November 1998, we published the Christmas Star as a novelty project and it proved extremely popular.

This year, our "just for fun" festive season project is in the shape of a Christmas Tree but the display is a lot more diverse and interesting because it uses bi-coloured LEDs. Not only can each LED produce 16 different colours, the LED Christmas Tree has a fascinating range of ever-changing patterns.

In fact, considering that the LEDs are red/green types, you will wonder how they can produce such a range of colours; some of them are quite odd.

As with last year’s Christmas Star project, this circuit uses just one IC (OK, one-and-a-bit!) and yet the patterns it produces are seemingly endless.

How does it do it? Yes, you guessed it. The Tree is controlled by a microcontroller but this one is different. While it can be programmed by most "high-end" (expensive) chip programmers, it can also be programmed (and re-programmed) by a PC parallel port with minimal hardware.

This makes it ideal for hobbyists. If you have been avoiding microcon-trollers because of the cost of the programming hardware, now there is no excuse!

And most of the development software can be downloaded free from the Internet – that avoids another excuse!