Abstract: The invention disclosed here is an anti-cycling device for high-pressure sodium lamps. A current sensor continually monitors lamp current and outputs a low voltage signal to an amplifier. When lamp current increases, indicating a starting or recycling condition, the sensor's voltage output correspondingly increases, and the amplifier responds by amplifying such output and transmitting it to a second amplifier. The latter acts as a voltage comparator and compares the first amplifier's output with a threshold level. Each time the first amplifier's output exceeds the threshold, the second amplifier outputs a trigger signal. Such signal is counted over time, and if the number of counts reaches a certain number, the counter outputs a malfunction signal to a relay that cuts off power to the lamp. An easy-to-see LED simultaneously illuminates to indicate the cycling condition and the need for lamp maintenance.

Abstract: A constant-current light sensing system employs a constant-current diode in series with the power lead to a photoconductive cell. This diode provides a substantially fixed current through the cell and enables the system to be designed such that it can make maximum use of the linear portions of the cell's output response curve, and maximum use of the range of a potentiometer's settings. The cell used in conjunction with the system is received in a housing that is easily mountable to a wall or ceiling surface by an adhesive material.

Abstract: A constant-current light sensing system employs a constant-current diode in series with the power lead to a photoconductive cell. This diode provides a substantially fixed current through the cell and enables the system to be designed such that it can make maximum use of the linear portions of the cell's output response curve, and maximum use of the range of a potentiometer's settings. The cell used in conjunction with the system is received in a housing that is easily mountable to a wall or ceiling surface by an adhesive material.

Abstract: A self-contained light sensor head (10) has a photodiode (18) operable to produce an electrical response proportional to light intensity, and an amplifier (20) that produces an output signal from the photodiode's response. The head (10) further includes a gain control circuit, for suitably controlling the gain of the output signal, and has noise and oscillation control circuits. The latter circuits permit the sensor to generate a low voltage output signal that is compatible for input directly to an analog computer.

Abstract: A system for monitoring the level of light at a distant location from a central location. A light sensor at the location to be monitored is comprised essentially of a photodiode and an operational amplifier and produces a high-level, analog output signal on an output signal line, the signal being linearly proportional to the level of light at the location. A control unit at a central location is electrically coupled to the sensor and comprises a power supply for providing electrical power to the sensor and a calibration device connected to the output signal line for providing a feedback signal to the sensor. The calibration device may be adjusted so that the output signal at the control unit bears a selected ratio to the light detected. A control unit having a single and power supply may be coupled to a plurality of sensors.