Abstract: A Style A PAPI system comprises a plurality of identical lamp housing assemblies, each with one or more lamps and each housing assembly including a tilt circuit. A master control includes a microcontroller that supplies an inverted 1 KHz, 50% duty cycle pulse signal to each tilt circuit through a corresponding blocking diode. Each of the tilt circuits includes an optical pendulum tilt switch that responds to tilting of the housing assembly. DC power is developed in each tilt circuit from one phase of the pulse signal. A pair of steering diodes and a voltage divider network enable return pulses to be supplied back to the microcontroller via the same wires that deliver the pulse train. The returned pulses exhibit different voltages corresponding to tilt and no tilt conditions of the tilt switch. Visual indications of the status of each tilt circuit are presented at the tilt circuits and at the master control.

Abstract: A Style B PAPI system comprises a plurality of identical lamp housing assemblies, each with one or more lamps and each housing assembly including: an electronic bypass circuit with first and second oppositely poled SCRs coupled across the terminals of each lamp; a zener diode; and a diode bridge for developing a first trigger voltage across the zener diode in the event of failure of a lamp. The first trigger voltage causes alternate conduction in the first and second SCRs from the AC voltage developed across the failed lamp. A lamp control circuit includes a third SCR that is coupled across the zener diode for developing a second trigger voltage for similarly driving the SCRs. The lamp control circuit is operated by a microcontroller-controlled common lamp control circuit that activates all of the lamp control circuits and disable all of the lamps in response to a tilt condition for the lamp housing assembly.

Abstract: An airport strobe lighting system includes a BCD source of pulses generating trigger voltages for a plurality of strobe lamps and a sensor circuit for comparing confirmation signals with the trigger pulses and generating corresponding return pulses indicative of the operation of the strobe lamps. A microcontroller is supplied with conditioned 5 bit address inputs from the BCD source of pulses and conditioned confirmation signal outputs from the sensor circuit and compares each confirmation signal with the 5 bit address of the corresponding strobe lamp. The microcontroller controls the illumination of dedicated LEDs to indicate the status of each of the strobe lamps.