Abstract: A zero inrush visual or visual/audible alarm circuit which includes a transistor switch and resistor combination connected in series with a storage capacitor provides inrush resistance for a period following initial power-on. The transistor switch may be controlled by a microcontroller or a simple timer.

Abstract: An audio/visual alarm system which includes multiple microprocessor-controlled alarm units connected in a common loop to a fire alarm control panel and an interface control circuit. The interface control circuit causes brief interruptions in power to the alarm units which synchronize operation of the alarm units and which can also be used as alarm control signals. The interface control circuit allows for control of both audio and visual alarms using only the single common loop connection between alarm units.

Abstract: The reflector of a strobe warning light for mounting on a wall has reflective surfaces for enhancing the amount of light projected into a sector defined by a horizontal reference plane and a vertical reference plane that intersect at the lamp axis, the lamp being oriented horizontally. Two wing-like reflective surfaces reflect light into a zone of the sector from 10 degrees to 40 degrees from the horizontal reference plane. Two other wing-like reflectors that adjoin the first two reflect light generally parallel to the lamp axis in opposite directions to increase the light intensity as the light is viewed from the sides. The wing-like reflective surfaces are located in diagonally opposite quadrants with respect to the horizontal reference plane and a plane at the lamp centerline perpendicular to the lamp axis, thereby leaving openings in the remaining two quadrants. A concave reflective surface behind the vertical reference plane reflects light away from the wall.

Abstract: A strobe alarm system which includes multiple normally self-timed strobe circuits connected in a common loop to a fire alarm control panel, and a sync control circuit, which may be incorporated in the fire alarm control panel, for causing the strobes to flash in synchronism at a predetermined rate which will insure that a person viewing the multiple strobes would not see flash rates higher than the predetermined synchronized rate, which is preferably less than five flashes per second. The sync control circuit does not interfere with the supervision functions of the alarm system, and when an alarm condition is present it supplies power to the strobe circuits which it then interrupts once every flash cycle to cause a sync trigger circuit in each strobe to fire its flashtube, and to reset the internal timer of each strobe to ready it for arrival of the next sync signal.

Abstract: A strobe alarm circuit includes a voltage source circuit which has a capacitor connected across its output terminals. The voltage source circuit is connected to a flash circuit which includes a flashtube shunted by a trigger circuit. The trigger circuit causes the flashtube to flash when the voltage across the voltage source circuit capacitor reaches a predetermined threshold firing voltage. A resistor divider network is employed in the trigger circuit to ensure that the flashtube is triggered at virtually the same instant as the voltage across the capacitor exceeds the trigger threshold value.

Abstract: A flashtube circuit includes a switch which in a first position regulates the storage over time of energy in a first energy storage device and in a second position allows the transfer of energy from the first energy storage device to a second energy storage device. A microcontroller receives the input voltage and then samples and digitizes it for input into a lookup table. The microcontroller repeatedly cycles the switch between flashes by controlling the time the switch is in its first position. The lookup table output provides the signal for determining the time the switch remains in its first position. The time interval from the last flash controls the time the switch is in its second position. The cycling of the switch is controlled accordingly such that the second energy storage device acquires the predetermined amount of energy for the flash just as the triggering circuit is initiated by the microcontroller.

Abstract: An interface for a supervised multiple input, audible warning system is disclosed. The interface continuously monitors or supervises a plurality of circuits between a control unit and an alarm unit for electrical faults. Each circuit represents a separate alarming condition. All the circuits are coupled to but normally isolated from each other and a common circuit for driving a piezoelectric device. The isolation is accomplished by means of a semiconductor switch normally reverse biased. The semiconductor switch prevents the supervising current of one circuit from driving the piezo by isolating all possible flow paths to all circuits without current flow in the alarming direction. Upon sensing an alarming condition, the direction of the current in the alarming circuit reverses resulting in forward biasing the semiconductor switch. The current in the alarming circuit, no longer isolated from the common circuit, actuates the common circuitry necessary for generating the audible warning.

Abstract: A strobe alarm circuit utilizing an optocoupler in the DC-to-DC converter portion of the circuit for repetitively connecting and disconnecting an energy-storing inductor across a DC power source. The light-emitting diode portion of the optocoupler is connected in parallel with a resistor connected in series with the inductor for continuously monitoring the current flowing through the inductor; when the inductor current has attained a particular value at which the voltage drop across the resistor is sufficient to turn on the LED, the switch portion of the optocoupler is turned on and disconnects the inductor from across the source. After a short interval determined by the parameters of the optocoupler and associated circuitry, the cycle is repeated.