Oscillator/driver circuit for fluxgate magnetometer

An improved oscillator/driver circuit for a magnetometer of the type having a transistor including emitter, base and collector terminals, and of the type having a drive winding and a control winding operatively wound on a magnetic core, one end of said drive winding being connected to the collector terminal of said transistor and the other end thereof being connected to ground, one end of said control winding being connected to the base terminal of said transistor and the other end thereof being connected to one end of a bias resistor forming thereat a junction, the other end of said bias resistor being connected to ground, and the emitter terminal of said transistor being connected to a power source so as to provide sufficient base current for turn on of said transistor and so as to provide positive feedback in the form of base current pulses from said drive winding to said control winding when said transistor is turned on, wherein the improvement comprises:

• means operatively connected between the power source and the junction formed by the other end of said control winding and the one end of said bias resistor so as to control the on time of said transistor by increasing the length of the base current pulses provided by the positive feedback from said drive winding to said control winding such that termination of the base current pulses and the turning off of said transistor is substantially controlled by saturation of said magnetic core, and after turn off of said transistor, said means cooperating with said bias resistor to keep said transistor turned off for a predetermined time before said transistor is turned on again thereby reducing the power normally required to operate said improved oscillator/driver circuit.