Abstract: A circuit to drive electromagnetically actuated displays. The circuit maintains a precise current level regardless of variations in supply voltage and drive coil resistance. The inductance of the drive coil is utilized to increase the efficiency of the current control.

Abstract: Apparatus for use in artificial respiration and the like, comprising an elongated tubular body having a flexible inner end portion adapted for insertion in the esophagus or trachea of a patient and an outer end portion for connection to a source of fluid. An inflatable cuff is carried at the inner end portion. The upper end portion of the tubular body includes an adapter, a seal for the lumen of the tubular body carried by the adapter and a plurality of closable openings spaced in the upper portion between the seal and the outer end of the tubular body. In the esophageal mode, the lumen of the tubular body is sealed to prevent the flow of fluids between the upper portion and lower portion of the tubular body. The openings in the upper portion are open to permit the flow of fluid therethrough into the patient's trachea and lungs. In the tracheal mode, the openings in the upper portion are closed, and the lumen of the tubular body is open to provide fluid communication through the tubular body.