Abstract: A driver that provides voltage level and polarity select control via a signal to an electrochromic device to vary light transmittance of the device. The driver has a fail-safe feature relative to the electrochromic device if a microcontroller of the driver fails. The driver is sufficiently efficient so as not to necessarily need a heat sink. The driver may sense and measure current and voltage into the electrochromic device.

Abstract: A system and method to parasitically take electrical power from a source of ac load power to provide a voltage source to directly power an associated control device is described. The system utilizes a controllable transconductance device to both selectively provide power to a controlled load and to develop a predetermined voltage to directly power the control device in a system where the ac load power is applied at one terminal and is passed through the transconductance device to be returned through the load. The system includes a means for establishing the predetermined voltage level to power the control device and for continuously monitoring that voltage level to maintain it as required, whether power is applied to the load or not. Alternative voltage regulators to provide isolated or non-isolated power to the control device irrespective of whether or not power is applied to the load are also described.

Abstract: A transmitivity sensor having a light source and a detector on one side of a medium with a reflector on the other side of the medium so as to reflect the light from the light source back through the medium to the detector. For instance, the sensor may be used on a window of a sealed building or container without having connections to the source and detector break the integrity of the window seal relative to the building or the container. The magnitude of the light signal on the detector relative to that of the source is an indication of the transmitivity of the window. Electronics to effectively implement the sensor are connected to the source and detector. The electronics may contain, for example, a source driver, a detector amplifier, a band-pass filter, a logarithmic amplifier and various voltage sources. Other items may be a part of the electronics as desired.

Abstract: A system and method to parasitically take electrical power from a source of ac load power to provide a voltage source to directly power an associated control device is described. The system utilizes a controllable transconductance device to both selectively provide power to a controlled load and to develop a predetermined voltage to directly power the control device in a system where the ac load power is applied at one terminal and is passed through the transconductance device to be returned through the load. The system includes a means for establishing the predetermined voltage level to power the control device and for continuously monitoring that voltage level to maintain it as required, whether power is applied to the load or not. Alternative voltage regulators to provide isolated or non-isolated power to the control device irrespective of whether or not power is applied to the load are also described.

Abstract: A dimmer for a fluorescent light in which the fluorescent light is supplied with an electrical signal having a varying magnitude, the dimmer positioning a notch of reduced signal magnitude within the electrical signal for controlling the illumination level of the fluorescent light wherein the illumination level is dependent upon the position of the notch within the varying electrical signal.

Abstract: An automatic light level control system for a video camera is disclosed which uses a time-variable camera clock for determining and controlling the scanning rate of the camera. A control means responsive to the light level of the video output of the camera controls the rate of the camera clock, and thereby the scan rate of the camera so that the light level of the video output is maintained within desired limits.