A Magnetic Orientation Device

A light weight, low current drain system for the geomagnetic orientation of experimental equipment during a high altitude balloon flight is here described. The system is specifically designed to keep nuclear emulsions oriented to within ±5 degrees of a chosen geomagnetic heading. The error detector consists of a high impedance ac bridge, two of whose arms are electrolytic resistance paths in ethyl alcohol. Deviation of a compass needle, immersed in the electrolyte, from a chosen ``on‐course'' line unbalances the bridge. A correcting motor is started when the off course deviation unbalances the bridge to a sufficient predetermined extent. Direction of motor rotation is determined by the sense of the error. Quiescent power drain is 1.4 watts. Motor operation increases this drain by 4 watts. Flight analysis of orientation is made possible by an integrating camera. Some control characteristics are given.