Colour changes to ambient temperature

In Techno Talk of May ’05, reference was made to an ambient-sensing light display known as the “Stock Orb”. It was quoted as being an ornament that glows in various colours depending on a number of external factors. These factors ranged from sensing the surrounding temperature, to the everchanging ups and downs of values on the Stock Market. The concept caused the author to slip on his thinking cap, yet again!

The design described here is a much simplified version of what the Stock Orb can probably do, using just a handful of components on a small printed circuit board. As presented, it simply interfaces to a rudimentary temperature sensor and controls five coloured l.e.d.s. Its ultimate use and interface to other sensors is up to the ingenuity of the reader, although some ideas are given later.