Abstract: Existing automatic log on/log off systems in telephone systems determine whether or not a workstation is occupied and whether calls can be directed to that workstation by determining whether or not the amplifier that provides the interface between the telephone system and the occupant's headset is plugged into the workstation. Recent headsets have included a connector in the cord between the headset and the amplifier, enabling the occupant to leave the workstation without unplugging the amplifier. However, this defeats the sensing mechanism of the existing automatic log on/log off system. An amplifier according to the invention replaces the existing amplifier and includes a detector for determining whether a communication link exists between the headset and the amplifier, and an activator for activating the existing automatic log on/log off system in the telephone system.

Abstract: A holder for a piezoelectric crystal wafer comprising a base, a pair of spaced apart leaf springs secured to the base and a seat member secured to the base between the leaf springs. The leaf springs spread outward upon the application of an external force, to permit the placement of a crystal wafer on the seat member and return toward a normal position upon the release of the external force, to resiliently hold the crystal wafer on the seat member.Each leaf spring includes a pair of prongs at the upper end thereof, separated by a slit having a width slightly larger than the thickness of the wafer. An elongated slot is formed in each of the leaf springs and having a width greater than the width of the slit between the prongs. When the crystal wafer is inserted in the holder, the upper part of the wafer is received in the slit of one leaf spring and a side portion of the wafer extends through the slot of the leaf spring.