Abstract: A drive circuit suitable for driving an inductive load such as an isolation transformer is disclosed having a driver stage and associated feedback circuitry. The driver stage has at least one output for connecting to the load and is switchable between a drive mode and an idle mode of operation. In the drive mode of operation, the driver stage produces a data output signal at the output which corresponds to a data input signal received by the driver stage. In the idle mode, the driver stage produces an idle signal, in response to a control signal, which functions to discharge the conductive load. The feedback circuit produces the control signal in response to the idle signal and adjusts the control signal so that the idle output signal will approach a predetermined neutral level. The inductor will proceed to discharge and, once discharged, will shift the idle voltage.

Abstract: A circuit for correcting a fault in an automotive system having at least two operating states includes an actuator mechanism for placing the system into one of at least two operating states and a switching mechanism, such as a relay, operatively connected with the actuator mechanism for driving the actuator mechanism upon passing a current through the switching mechanism. The circuit further includes a fault warning mechanism for detecting an inability of the actuator to place the system into a desired operating state and for generating a fault warning signal in response to the detection as well as a control unit for activating the switching mechanism according to a predetermined sequence upon generation of the fault warning signal to correct the inability of the actuator mechanism to place the system into a desired operating state.

Abstract: An output circuit having a fail-safe function with: a control signal generating circuit which generates a control signal to control the current of a load and includes an operational amplifier which amplifies a difference between a control value and a feedback value to produce the control signal; a drive circuit which drives a load according to the control signal from the operational amplifier; an output current detecting circuit for detecting a current in a load solenoid and adding an offset current to the detected current, with the output of the output current detecting circuit being fed back to the control voltage generating circuit as the feedback value.

Abstract: An input/output circuit for performing tests prior to controlling an electrical load (2) which is decoupled by a transformer (5). An input (E) thereto acts on a first switching member (6) connected in series with a primary winding of the transformer in a power supply circuit for said primary winding. An output (S) provides a signal on the basis of the voltage present across the terminals of an output resistor (7) connected in series with the primary winding of the transformer in the power supply circuit of said winding. A second switching member (3) is inserted in series with the load in a power supply circuit for said load, and is controlled from the input to the input/output circuit via the transformer and a rectifier circuit (10) connected to the terminals of a secondary winding of the transformer. An impedance-switching circuit (13, 16) is connected to the terminals of the second winding in order to act on the input/output circuit by changing the voltage across the terminals of its output resistor.

Abstract: A solenoid current control system includes a microprocessor which periodically generates a desired peak current value and which energizes the solenoid coil. Current through the coil is sensed via a series resistor and the sensed current is compared to the desired peak current by comparator. The comparator generates an interrupt signal when the sensed current reaches the desired peak value. The interrupt signal is applied to the microprocessor which responds by de-energizing the coil.

Abstract: An underload protection system for an electric motor connected to first and second power supply lines, the lines being connectable to an AC power supply. The system comprises a line voltage sensing circuit connected to the first line and having a line voltage signal impressed therein, and an amplitude adjustment circuit connected to the voltage sensing circuit for adjusting the line voltage signal to produce an amplitude adjusted voltage signal. A line current sensing circuit is connected to the second line and has a line current signal impressed thereon, and a phase adjustment circuit is connected to the current sensing circuit for adjusting the phase of the current signal to produce a phase adjusted current signal.