Sherwood Medical Company

Michael J Wilhelm

Clarence L Walker

Denis Y Yerlikaya

Randall J Krohn

Curtis D Kinghorn

A drop detector circuit and method are provided for a drop detector of the type including a drop chamber and an electro-optical sensor. A detector detects drops passing through the drop detector in an optical sensing path between the detector and at least one light source. In response to the detection of a drop passing through the optical path, the detector produces an output signal. A capacitor is connected between the detector and an amplifier to block the DC component of the output signal. After amplification, the signal is passed through a low pass filter to further block signals caused by undesirable factors. The cutoff frequency of the low pass filter is controlled by a microprocessor that controls the pump that pumps liquid from the drop chamber. The detector and light source or sources are arranged to detect drops falling in the drop chamber at virtually any angle and in virtually any ambient light condition.

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Rolla, MO, United States of America

Michael J Wilhelm