Abstract: A "U" shaped yoke for retaining a pair of ear couplers to the ears of an individual at a minimum effective pressure in an acoustic system. A pair of right-angle horns carry the ear couplers and are rotatively mounted at the extremities of the U to allow optimum adjustment of the couplers to the ears of the wearer. The structure is assembled without adhesive and may be disassembled.

Abstract: A flat electrical connector employing axially compressed helical springs for contacts. The springs float in a housing between two flanking insulative members having printed circuit contact areas to mate with each end of each spring. The connecting force required to press one insulative member against one end of each spring is minimal, and the disconnecting force is negative. The springs may power enclosing telescoping contacts that function in the same manner as the springs alone.

Abstract: A transducer switching system for, in effect, removing electrical energy from a transducer without breaking the electrical circuit. A resistor is in series with the transducer. An electro-mechanical switch shunts the resistor. The switch is within the enclosure containing the transducer. When the acoustic connector of a use-element, such as a stethoscope type headset for a listener, is inserted into the enclosure the switch is changed from its normally open state to a closed state, thereby shorting out the resistor and allowing an effective level of electrical power to operate the transducer. Two systems may be simultaneously actuated for stereophonic sound.

Abstract: A hub for driving a reel of tape, having a resiliently mounted radially expandable key for nesting in a keyway of the axial hole in the reel. The reel may be placed upon the hub in any circumferential relation with one hand and relative rotation will cause the key to move radially outward when the keyway is aligned with it. Cessation axially of the keyway at the front of the reel and a corresponding catch on the front of the key secures the reel axially upon the hub.

Abstract: A roller for operation in a gaseous environment, perhaps containing solid particles; the roller requiring cooling. A central axial cylindrical aperture surrounding a shaft upon which the roller rotates has a continuous helical groove that extends the full length of the aperture. Upon rapid rotation gas traverses the groove, cooling the roller and removing any solid particles otherwise trapped between the aperture and the shaft.

Abstract: A plural phase stepping motor control circuit in which damping is accomplished by energizing a previously energized phase prior to the expiration of the power cycle on a pair of other phases. The duration of the damping pulse is inversely proportional to the speed of operation. The logic involved allows for forward or reverse running. A sprocket latch circuit locks out spurious overshoot responses, such as may be caused by vibration, damaged tape, or other irrationality.

Abstract: A plural phase stepping motor control circuit in which damping in accomplished by energizing a previously energized phase prior to the expiration of the power cycle on a pair of other phases. The duration of the damping pulse is inversely proportional to the speed of operation. The logic involved allows for forward or reverse running. A sprocket latch circuit locks out spurious overshoot responses, such as may be caused by vibration, damaged tape, or other irrationality.