Abstract: The disclosed technology includes pre-filter system that can include a filter portion comprising pipes, elbows, and tees. The pipes can include apertures. The pipes, elbows, and tees can be positioned such that a first end of a first group of neighboring pipes can be fluidly connected to form a column of fluid connection and a second end of a second group of neighboring pipes can be fluidly connected to form a row of fluid connection. The apertures of at least some of the pipes can be covered with a mesh netting. The pre-filter system can include an airtight float portion. The float portion can be attached to the filter portion to provide a predetermined amount of buoyancy to the pre-filter system.

Abstract: The disclosed technology includes pre-filter system that can include a filter portion comprising pipes, elbows, and tees. The pipes can include apertures. The pipes, elbows, and tees can be positioned such that a first end of a first group of neighboring pipes can be fluidly connected to form a column of fluid connection and a second end of a second group of neighboring pipes can be fluidly connected to form a row of fluid connection. The apertures of at least some of the pipes can be covered with a mesh netting. The pre-filter system can include an airtight float portion. The float portion can be attached to the filter portion to provide a predetermined amount of buoyancy to the pre-filter system.

Abstract: An electronic security sentry for monitoring a designated area to detect unauthorized intruders comprises a housing that contains a microprocessor controller, a power source, and a two-way radio transmitter coupled to the microprocessor. The microprocessor controller includes storage for storing the digital equivalents of a predetermined set of verbal commands. A set of passive infrared detectors are coupled to the controller and mounted to the housing such that their fields of coverage span the area to be monitored. Upon detection by the sensors of an unauthorized intruder, a signal is conveyed to the microprocessor which selects a predetermined set of digitized verbal commands from its memory, activates the two-way radio in its transmit mode, and conveys the commands in a predetermined sequence to the two-way radio. The sequence of verbal commands are then transmitted by the radio for receipt by the security guards of an adjunct guard force, who can respond to the alarm accordingly.

Abstract: A multiplexed liquid crystal display arrangement including a back plane (241) driven by a signal (212) derived from a common clock signal (200). The clock signal on the back plane is also provided to one input of an EXCLUSIVE OR gate (245b) the other input of which is the incoming multiplexed data. A second clock signal (211) drives the multiplexing counter (141) which in turn drives the address lines (221) of an analog multiplexer (138). Each segment of a multi-segment liquid crystal display having the common back plane (241) has attached thereto a capacitor (C1 through C64) acting as a temporary storage for the signals. A spike suppression flip-flop (247) is used to disable the multiplexer during changes on the address lines in order to suppress output spikes which occur during such changes. The period of the spike suppression pulse is selected to be short with respect to the on period of each segment in the multiplex timing.

Abstract: An interface for connecting a PBX line (18) to a central office trunk (15) and for providing a supervisory signal (28) and accepting PBX hook switch and dial pulse inputs (30), being readily adaptable to ground start trunks and loop start trunks. A pair of transistor switches (55, 56) sharing a common base drive (57) is biased by a differential bias means (59, 60, 61) to operate a ground start isolated switch (32, 35) and an isolated loop closing switch (36, 37). The supervisory signal is controlled by a comparator (45) which senses grounding of central office tip (16) to establish the supervisory signal and is subsequently responsive only to the presence of current in the central office loop detected by a relay (65) buried in a coupling transformer.

Abstract: A data distribution system for a private branch telephone exchange for providing information to a plurality of PBX stations. Two embodiments (serial and parallel) including addressable stations are shown. Memory devices driving a plurality of displays at each station are updated in response to command signals from a controller preceded by the station address. Each station may communicate with the controller and transmit keyed-in signals or information reflecting station availability. A novel multiplexed LCD, switching matrix bypass upon controller failure circuit, and bus protection circuit upon remote power supply failure are also shown.

Abstract: A private automatic branch telephone exchange system which includes an integral system for maintaining and updating selected data information. Interconnections between subscriber lines and trunk lines are accomplished with a unique non-blocking switching matrix which allows switching interconnections to be independently made and terminated without blocking subsequent interconnections on the same circuits. Various information signal functions, such as dial tone and ring-back, are selected by multiplex circuitry which is external of the switching matrix, so that all switching matrix trunks are available for voice and ring signal connections. The switching matrix is operated by a circuitry including a programmed digital computer, and provides substantial flexibility of control and service functions. Subscriber line status is monitored at all times, so that available special services can be accomplished by a subscriber in response to dialing selected digits.