A light circuit control apparatus for controlling the illumination of a predetermined area is described comprising a photocell coupled to a first comparator circuit for generating a "light-on" signal when the ambient light in the predetermined area decreases to a first predetermined intensity and a second comparator for generating a "light-off" signal when the ambient light in the predetermined area increases to a predetermined intensity, and logic circuits including flip-flops for turning on and turning off a plurality of lighting circuits in a predetermined sequence in response to the "light-on" and "light-off" signals generated by the comparator.

According to the present invention a low voltage storage warehouse lighting system has a plurality of switch sets, a plurality of light sources, and a timer-relay station. Each switch set comprises a plurality of light switches electrically connected in serial with one another via low voltage wiring. The switch sets are located proximate associated file aisles. The low voltage wiring is disposed within the racks. A light source is located above each file aisle. Each light source is associated with one switch set and each said switch set associated with one light source. The timer-relay station is electrically connected via high voltage wiring to a breaker panel, via high voltage wiring to each light source, and via low voltage wiring to each switch set. The timer-relay station is adapted to transform high voltage input to low voltage and to illuminate each light source in response to electrical signals received from the switch set associated with the light source. Also, each file aisle has a corresponding preset time delay. The timer-relay station is adapted further to turn off the light source after the corresponding preset time delay.

A circuit arrangement according to the invention is intended to be used in a PIR motion-activated lighting fixture of the type that includes a triac for energizing the light from the AC power mains and a triac firing circuit for firing the triac in response to motion. To provide the accent lighting level and to control the magnitude of that level, the circuitry includes a window comparator, in which the thresholds are set to defining a dimming window, and a filter circuit responsive to the AC power line and providing an input signal to the window comparator. The filter circuit includes a circuit arrangement for shifting the phase of the input signal with respect to the AC power line signal and for contemporaneously scaling the amplitude of the input signal with respect to the AC power line signal such that the peak amplitude of the input signal diminishes as the phase shift of the input signal increases. That is to say, the amplitude and the phase shift of input signal to the window comparator are scaled together. The magnitude of the phase shift and concomitant amplitude scaling may be set by the user. The circuitry further triggers the triac firing circuit in the absence of motion at the phase angle at which the input signal exceeds the dimming window. With this arrangement the light is energized during a fraction of the AC cycle determined by the magnitude of the input signal phase angle that may be adjusted by the user at the installation site.

An electrical controller for actuating a number of electrical devices in accordance with control inputs received from a number of control input sources includes a number of optical isolators having inputs coupled to the control input sources. The optical isolators function to electrically isolate each of the control input sources from each other and to provide individual control voltages corresponding to the control inputs received from the control input sources. The outputs of the optical isolators are coupled through a user-actuable matrix switch to the coils of a number of relays which, in turn, control the electrical devices. Through various settings of the matrix switch, various ones of the electrical devices can be actuated in response to control inputs received from particular ones of the control input sources. Electrical isolation is maintained among the control input sources to avoid the development of undesirable feedbacks to the non-actuated control input sources.

A video display system is normally operated to produce a low brightness display on a CRT. Viewer sensing apparatus, including a transmitter and a receiver, senses the presence of a viewer by reflection of ultrasonic energy and operates a transistor having a time delay switch coupled in its load circuit for instantaneously supplying full power to the display system to produce a normal brightness display on the CRT. A transistor override circuit simulates closure of the time delay switch in response to an override signal for producing a full brightness display on the CRT independent of the time delay switch. The time delay switch maintains a full brightness display on the CRT for a predetermined time after the viewer leaves.