Abstract: A stack of piezoelectric discs for driving the diaphragm of a transducer such as a loudspeaker. The discs are arranged in pairs with the outer edges of each pair supported by engagement with an O-ring against their planar faces. The pairs are connected by studs fixed at the centers of the discs. One end of the stack is secured to a support, and the other end is connected to the diaphragm. In an alternative embodiment, another disc is attached to the stack, with an O-ring cemented between its nodal circle and a rigid support, and a diaphragm is attached to the rim of the disc.

Abstract: An omnidirectional antenna array comprising a ferrite antenna inductively coupled to one leg of a loop antenna that lies in a plane parallel to the long axis of the ferrite antenna. The output signal may be taken from either of the antennas.

Abstract: An interconnect circuit arrangement for patching a simplex or half-duplex radio network into a standard telephone system. It includes means for sending beep tones to the parties at the end of each message so that they can readily recognize when each is supposed to talk. The tones are sent automatically when the party on the telephone system concludes his messages, and under manual control of the party at the radio end when he concludes his. Special access codes are provided to prevent unauthorized access to the radio system and to set the circuit for special functions. Various override features are included to facilitate operation and avoid time delays that have heretofore tended to hinder conversations in VOX simplex and half-duplex radio systems.