Abstract: The sonar transducer includes a metal core about which is situated a cylindrical piezoelectric ceramic ring element with paper interposed therebetween. In order to improve resistance to fracture resulting from mechanical shock, in one embodiment, the core is reduced in diameter, such that a potting compound can be situated between the paper and the ring. In a second embodiment, the ring element is divided into two individual, axially aligned cylindrical ring subelements with a gasket interposed therebetween.

Abstract: The sonar transducer is protected from explosion shock by a variable impedance device, such as a metal oxide varistor, connected in parallel with the energy conversion component. The varistor normally has a very high electrical impedance, but becomes conductive upon application of the very high voltage output of the energy conversion component as a result of a rapid increase in mechanical energy, such as would accompany an underwater explosion in the vicinity of the transducer, to limit both voltage and current to a safe level so that the transducer can thereafter operate within acceptable parameters.

Abstract: A method and apparatus for reducing the low frequency electric and magnetic fields associated with electric blankets and mattress pads includes a power form converter inserted between the heating element of the electric blanket or mattress pad and the AC power source. In one embodiment, the power form converter is an AC to DC converter. In another embodiment, the power form converter is a full wave bridge rectifier circuit. The power form converter may either be built into the electric blanket or mattress pad, or may be external so that an existing electric blanket or mattress pad may be used in conjunction with the power form converter.

Abstract: The underwater sound projector includes a hollow-cylindrical metal housing having a recess with an opening. A non-ceramic flexural disc is supported over the opening. Within the recess is a stack of piezoelectric ring elements. A metal drive head transfers force axially from the stack to an annular area on the disc spaced from the center thereof. Foil electrodes are interposed between the piezoelectric rings and situated at the ends of the stack. A stress bolt clamp connects the drive head to the housing with the stack situated therebetween.

Abstract: A magnetic drive is provided for a flextensional transducer in order to adapt the flextensional transducer for operation at increased ocean depths without the necessity of liquid filling and complex decoupling devices. In one embodiment an electro-magnetic actuator is positioned between the walls of the flextensional shell and is driven electrically so as to deflect the shell walls outwardly. The magnetic actuator in one embodiment includes a permanent magnet and pole pieces supported on one of the interior walls of the shell, with a moving coil positioned between the pole pieces and supported on a diametrically opposite wall of the shell. In an alternative embodiment, the magnetic actuation may be in the form of a rod of magnetostrictive material between opposing interior walls of the shell, which is actuated by an overwound electrical coil, with the shell being of magnetic material such as magnetic iron.