Abstract: An acoustic transducer includes a sound-producing member at least partially disposed within the first magnetic flux gap region between the magnetic poles. The sound-producing assemblage is magnetically excited through a magnetic circuit that passes from a location outside the magnetic flux gap region to inside the magnetic flux region through an air gap. The moving member is controllably movable under the influence of at least one varying magnetic field, and its movement is constrained by a unique combination of mechanical restraints and magnetic restraints imposed upon the moving member by the interaction of a plurality of magnetic fields.

Abstract: An acoustic transducer includes a sound-producing member at least partially disposed within the first magnetic flux gap region between the magnetic poles. The sound-producing assemblage is magnetically excited through a magnetic circuit that passes from a location outside the magnetic flux gap region to inside the magnetic flux region through an air gap. The moving member is controllably movable under the influence of at least one varying magnetic field, and its movement is constrained by a unique combination of mechanical restraints and magnetic restraints imposed upon the moving member by the interaction of a plurality of magnetic fields.

Abstract: A transducer utilizes a sound-producing member positioned in the area of magnetic flux concentration between magnetic poles of opposite polarity. The sound-producing member is variably vibratable in a magnetic structure between the poles to generate acoustic waves, and an acoustic conduit carries the acoustic waves through the magnetic poles e to a location outside the magnetic structure.

Abstract: An acoustic transducer includes a sound-producing member at least partially disposed within the first magnetic flux gap region between the magnetic poles, the sound-producing assemblage is magnetically excited through a magnetic circuit that passes from a location outside the magnetic flux gap region to inside the magnetic flux region through an air gap.

Abstract: A transducer utilizes a sound-producing member positioned in the area of magnetic flux concentration between magnetic poles of opposite polarity. The sound-producing member is variably vibratable in a magnetic structure between the poles to generate acoustic waves, and an acoustic conduit carries the acoustic waves through the magnetic poles e to a location outside the magnetic structure.

Abstract: A tube can be repaired from its interior surface by inserting into the tube a cylindrical repair member The cylindrical repair member is a memory metal which has a first martensitic size that is less than the internal diameter of the tube, and a second austenitic size that is at least as large as or larger than the internal diameter of the tube. The cylindrical repair member is inserted into the tube in the martensitic state and heated, causing it to revert to the austenitic state thereby expanding and covering said hole, forming a tight bond with the internal surface of the tube.

Abstract: An acoustic transducer includes a sound-producing member at least partially disposed within the first magnetic flux gap region between the magnetic poles, the sound-producing assemblage is magnetically excited through a magnetic circuit that passes from a location outside the magnetic flux gap region to inside the magnetic flux region through an air gap.

Abstract: A memory metal plug adapted to seal tubes includes a central shaft and a plurality of discs extending radially from said shaft. The shaft extends beyond the first and last disc. The juncture of the discs and the shaft is radiused, and, further, the thickness of the discs decreases near the perimeter of each disc. This allows the discs to be swaged significantly without breaking, which, in turn, facilitates their use in plugging tubes.

Abstract: A memory metal or Nitinol plug is inserted into a tube and heated to cause the plug to expand as it transforms from a martensitic state to an austenitic state. The plug is held by a tool connected to an electric conductor. The tube is then grounded and current is run through the holder, the plug, and, in turn, the tube. Electrical resistance causes the plug to heat up and revert to the austenitic state. The holder is preferably a tube with an internal collet, spring urged into a closed position adapted to grasp a post of the Nitinol plug. To separate the holder from the plug, the collet is pulled to an expanded position by pulling the holder from the tube. This allows the collet to open and separate from the plug.

Abstract: A transducer utilizes a sound-producing member positioned in the area of magnetic flux concentration between magnetic poles of opposite polarity. The sound-producing member is variably vibratable in a magnetic structure between the poles to generate acoustic waves, and an acoustic conduit carries the acoustic waves through the magnetic poles e to a location outside the magnetic structure.

Abstract: A transducer utilizes a sound-producing member positioned in the area of magnetic flux concentration between magnetic poles of opposite polarity. The sound-producing member is variably vibratable in a magnetic structure between the poles to generate acoustic waves, and an acoustic conduit carries the acoustic waves through the magnetic poles e to a location outside the magnetic structure.

Abstract: An audible alarm has first and second acoustic chambers that deliver sound to respective first and second horns. A phase adjustment circuit for delays the phase of sound generated in one of the two chambers so that sound emerging from the two horns is delivered with the same phase and same frequency, and emerging sound from the two horns is additive.

Abstract: A transducer utilizes a sound-producing member positioned in the area of magnetic flux concentration between magnetic poles of opposite polarity. The sound-producing member is variably vibratable in a magnetic structure between the poles to generate acoustic waves, and an acoustic conduit carries the acoustic waves through the magnetic poles e to a location outside the magnetic structure.

Abstract: A plug assembly for a tube includes a tapered wedge and a sleeve. The sleeve fits over the wedge and is placed in a tube. Relative movement of the wedge and the sleeve causes the sleeve to expand and plug the tube. The exterior surface of the wedge and the interior surface of the sleeve include annular grooves. One or more compression rings in either the grooves in the sleeve or wedge permit motion of the sleeve relative to the wedge only toward the large diameter portion of the wedge. This prevents the sleeve from separating from the wedge after being installed in a tube.

Abstract: An audible alarm has first and second acoustic chambers that deliver sound to respective first and second horns. A phase adjustment circuit for delays the phase of sound generated in one of the two chambers so that sound emerging from the two horns is delivered with the same phase and same frequency, and emerging sound from the two horns is additive.

Abstract: A hearing aid is configured and dimensioned so as to be inserted past the cartilaginous part of the external auditory canal (external acoustic meatus) and into the bony part of the external auditory canal. The outer portion of the hearing aid fits snugly into the cartilaginous part of the external auditory canal; the microphone is located at the acoustic focus of the ear such that the natural sound and direction gathering functions of the human outer ear are fully utilized by the hearing aid. The inner portion of the hearing aid is articularly joined to the outer portion to enable the inner portion to be positioned past the sigmoid portion of the external auditory canal and forms a soft covered, elongated speaker which fits within part of the bony part of the external auditory canal, without causing discomfort to the human user.

Abstract: A hearing aid is configured and dimensioned so as to be inserted past the cartilaginous part of the external auditory canal (external acoustic meatus) and into the bony part of the external auditory canal. The outer portion of the hearing aid fits snugly into the cartilaginous part of the external auditory canal; the microphone is located at the acoustic focus of the ear such that the natural sound and direction gathering functions of the human outer ear are fully utilized by the hearing aid. The inner portion of the hearing aid is articularly joined to the outer portion to enable the inner portion to be positioned past the sigmoid portion of the external auditory canal and forms a soft covered, elongated speaker which fits within part of the bony part of the external auditory canal, without causing discomfort to the human user.

Abstract: An air cleaner with a smoke alarm unit for a forced air recirculating system is disclosed. The smoke alarm unit is housed within a module that fits within the frame of the air cleaner with minimal impact on the cleaning ability of the cleaner. In a preferred embodiment of the invention, a battery capacity tester and air cleaner functionality detector are included in the module. Signals from the battery tester and functionality detector are used by the smoke alarm unit to drive an alarm generator with different signals to produce distinguishable alarms for a smoke condition, low battery condition, and an air cleaner failure. A control unit may receive any of the alarm conditions to execute different control actions in the forced air system.

Abstract: A hearing aid is configured and dimensioned so as to be inserted past the cartilaginous part of the external auditory canal (external acoustic meatus) and into the bony part of the external auditory canal. The outer portion of the hearing aid fits snugly into the cartilaginous part of the external auditory canal; the microphone is located at the acoustic focus of the ear such that the natural sound and direction gathering functions of the human outer ear are fully utilized by the hearing aid. The inner portion of the hearing aid is articularly joined to the outer portion to enable the inner portion to be positioned past the sigmoid portion of the external auditory canal and forms a soft covered, elongated speaker which fits within part of the bony part of the external auditory canal, without causing discomfort to the human user.

Abstract: An air cleaner with a smoke alarm unit for a forced air recirculating system is disclosed. The smoke alarm unit is housed within a module that fits within the frame of the air cleaner with minimal impact on the cleaning ability of the cleaner. In a preferred embodiment of the invention, a battery capacity tester and air cleaner functionality detector are included in the module. Signals from the battery tester and functionality detector are used by the smoke alarm unit to drive an alarm generator with different signals to produce distinguishable alarms for a smoke condition, low battery condition, and an air cleaner failure. A control unit may receive any of the alarm conditions to execute different control actions in the forced air system.