Abstract: A DC current control is provided for inductive loads which achieves high energy efficiency even though the supply voltage may be subject to considerable variations.The inductive load may be a DC motor, a solenoid, or similar device. The electric power is applied directly to the inductive load through a switching means which closes the circuit to apply a charging current to the inductive load for fixed on periods of time.A discharge path is provided for the inductive load when the switching means opens the charging circuit. The discharge current is monitored, and when it decays to a selected value, the switching means is again closed for the fixed on charge time.

Abstract: In response to a signal to open and close a solenoid-operated valve, which is urged closed by flow of fluid through it, a circuit supplies a large current to the solenoid to open the valve, reduces the current to hold the valve open, and interrupts the current to close the valve. The circuit provides high electrical efficiency during operation. One embodiment of the invention is particularly suitable for use in systems in which the voltage of the power source varies over a wide range.