Importance

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Abstract

An apparatus for energizing the coil of, and detecting the resultant armature actuation in, a solenoid of the type having a movable armature reciprocable along an axis between first and second positions, a spring bias normally biasing the armature toward the first position, and an actuating coil for inducing a force on the armature tending to move the armature from the first position toward the second position in response to current flow in the actuating coil. A voltage is first provided to the solenoid coil and thereafter, a resulting current flow is differentiated and a zero crossing comparator is utilized to determine when the differentiated current is zero and, therefor, the time at which the sensed current flow reaches a maximum (dv/dt=0). The time at which the armature began to move in response to the resulting coil current may be inferred and the voltage to the solenoid coil interrupted a Predetermined time after the time at which the armature began to move.

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First Claim