Abstract: A personal security alarm system which activates audible and visible alarms instantly at the location of an emergency, and simultaneously notifies security personnel of the existence and location of the emergency so that response to the call for help can be immediate. When a person is threatened, the person actuates a hand-held alarm actuator-transmitter by pressing a pushbutton. The signal is received by an area relay receiver which triggers an alarm at the location where the incident is occurring. At the same time the area relay receiver relays the state of emergency to a master computer which identifies the area relay receiver activated by the hand-held alarm actuator-transmitter. The master computer activates an annunciator and displays on a color video screen graphically and in print the floor plan or the site layout where the incident is occurring. A portable device is provided for resetting the portable alarm activator.

Abstract: A variable area capacitance transducer for measurement of length and displacement is disclosed. The preferred embodiment uses three concentric cylinders. The innermost cylinder acts as a working electrode, the middle cylinder acts as a common electrode, and the outer cylinder, a reference electrode. A movable concentric cylinder acts as a shield and is guided for movement between the working and common electrodes. The capacitance of the transducer is related to the displacement of the shield.

Abstract: An atmospheric sampling pump arrangement employing a mass flow sensor which electronically monitors mass flow and compares it to a set-point value. The pump is then controlled in a manner that will minimize the difference between the measured flow and the set-point value. When the flow output drops below a predetermined value, a signal is energized to indicate the inability to maintain the desired flow. The system also incorporates a timer circuit which counts up the total amount of time that loss of flow regulation exists. After a predetermined period of cumulative loss of flow regulation, typically 30 minutes, a signal is energized to indicate this condition.

Abstract: A motor control system, particularly adapted for use with a battery-operated atmospheric hazard sampling pump, which can vary motor speed over a range of 50:1 with the use of a voltage controlled pulse width modulator. The system includes a back EMF circuit which develops a voltage, proportional to motor speed, which is compared with a speed reference signal to develop an error signal for the pulse width modulator. Automatic shutdown of the motor occurs for controlled periods when a blocked pump condition occurs and motor current rises above a predetermined limit.

Abstract: A voltage regulating circuit is provided for low voltage battery-powered measuring instruments of the type using electrically-heated filaments as sensing elements. The circuit includes an indicating signal light which is energized from a separate control power source and controlled by the voltage regulating circuit and also in response to energization of a filament in the instrument. The light is turned OFF in case of failure of the control power or of inability of the voltage regulating circuit to maintain the desired voltage. The light is also turned OFF for a set time period upon energization of the filament to allow the filament to stabilize at its normal temperature. Thus, when the indicator light is ON an indication is provided that the instrument is in condition for use.