The digital compass published in last month's issue of this magazine used a Pewatran Type 6945 magnetic sensor. This device was shown to enable the construction of an electranic compass with relatively few additional components. True, it has aresolution of only 45°, but this is perfectly acceptable for many applications.The analogue sensor, Type 4070, also fram the Swiss firm Pewatran, enables a fully- fledged replacement (resolution 0.5°!) for a magnetic compass to be constructed. As already pointed out in last month's article,this requires fairly complex circuitry. Moreover, the data pravided by the sensor cannot easily be evaluated without the use of a microcontroller.