BMR photoelectronic magnetographs

Abstract

New magnetic observatories in Australia are being equipped with commnercial digital fluxgate magnetographs. However, where appropriate buildings and classical instruments already exist, devices designed and developed by the Bureau of Mineral Resources (BMR) (the MPE-1, horizontal and the MPE-2, vertical), are being added to provide visual charts and digital records. MPE work on the force-balance principle: when the earth's field varies, the couple exerted on a suspended magnet is counteracted by a couple from an opposite artificial field. The latter is produced by a null-detector/electronic-servo system, and the servo voltages are measures of the field variations.