Analysis of a Feedback Galvanometer Amplifier with Inductive Source and Its Application to the Detection of Geomagnetic Micropulsations

The response characteristics of a galvanometer amplifier having an inductive source impedance and employing negative feedback may be determined easily and quickly by means of log-magnitude techniques. Galvanometer amplifiers for geomagnetic micropulsation detection systems are analysed, and the effects of series and of parallel feedback are considered. It is shown that by varying the nature and the amount of feedback a variety of frequency response curves may be obtained from a given detector coil and galvanometer. A practical series feedback amplifier operating from an iron-cored detector coil and having an amplitude response following an approximate dH/dt law to 2 Hz with an output of 100 mV/¿H is described.