Switching amplifier circuit

A switching current supply circuit, responsive to a control voltage, for controlling the current flowing in an inductive load comprising

• a pair of terminals adapted for connection to such a load,
• means operatively connected to said terminals for producing a voltage indicative of the current flowing through any such load connected to the terminals,
• comparator means, responsive to a differential input voltage including components derived at least in part from such a control voltage and from said load-current-indicating voltage, such voltage components tending, when added, to null one another, for generating a switched output voltage having one of two distinct values, each of said values indicating one of the two possible relative polarities of said input voltage,
• hysteresis means operatively connected to said comparator means for delaying switching therein by a known period of time progressing from the point in time when the magitude of the component of said input voltage derived from said load-current-indicating voltage is equal in absolute value to but opposite in polarity from that of the component derived from the control voltage, and
• a polarity-changeable voltage source operatively connected to said producing means, and therethrough to said terminals, for applying, selectively and reversibly, and in response to said output voltage, known voltages of opposite polarity to said terminals, which known voltages have, in one operating state of the circuit, one known polarity respecting said terminals, and in a second operating state, the reverse polarity respecting the terminals, said operating states effecting a change in load current level appropriate to decrease the absolute value of said input voltage.