Alliedsignal Inc.

Honeywell International Inc.

Terry J Ahrendt

Stephen G Abel

A circuit arrangement is described which detects when the moving member of an electromagnetic device is in motion by detecting coincidence of energization of the device coil and a negative first differential of the current/time waveform and a positive first differential of the voltage/time waveform through said coil.

Solenoid motion detection circuit

A stepper motor shaft position sensor differentiates the current provided when the stepper motor is excited as by a step command voltage. The differentiated current is, in effect, a signature indicative of whether or not the motor shaft has taken a step. If the differentiated current falls below a predetermined level within a predetermined interval the motor shaft has taken a step as indicated by a sensor output at a predetermined logic level. Otherwise, the sensor output is at another predetermined logic level indicating that a step has not been taken and the motor is in a stalled condition. The sensor output is applied to a utilizing means which provides a continuous verification of the steppper motor shaft position.

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Mesa, AZ, United States of America

Terry J Ahrendt