Transistorised PHF magnetometer

There is a requirement to measure small magnetic fields of the order of milligauss produced by minesweepers. The smallest field that can be measured accurately by conventional magnetometers is about 2 milligauss. Proton Precession magnetometers and Peak Height Fluxgate magnetometers are commonly used to measure magnetic fields of the order of 1/10 milligauss. A Peak Height Fluxgate magnetometer system has been developed at the Indian Naval Physical Laboratory, Cochin, using a Mu-metal core detector. For some specific applications, it is necessary to have a transistorised version of the PHF equipment. The paper describes the transistorised Peak Height Fluxgate magnetometer fabricated at the Indian Naval Physical Laboratory. The instrument records a minimum field of 1/10 of a milligauss and the sensitivities available are 1·25 mG and 2·5 mG per inch deflection on a Pen and Ink recorder