Abstract: A door assembly for selectively interlocking opposing doors each pivotably mounted at a hinge side thereof to a door frame so as to both open and close in the same direction includes a door handle assembly mounted to one door at a latch side thereof opposite the hinge side and carrying a first plurality of magnets, and another door handle assembly mounted to the other door at a latch side thereof opposite the hinge side and carrying a second plurality of magnets. The door handle assemblies are arranged relative to each other with the first and second pluralities of magnets aligned such each aligned pair of the first and second pluralities of magnets have opposite magnetic polarities, and the aligned first and second pluralities of magnets magnetically couple to each other as the door handle assemblies are brought into contact with each other.

Abstract: A public address amplifier comprises a housing which contains an output amplifier connected to loudspeakers. A microphone containing a microphone transducer and an input amplifier is connected to the input of the output amplifier and to connectors on the housing by a cable. A second such public address amplifier can be connected to the first by connecting its cable to one of the connectors so as to provide a public address system of increased power.