Abstract: The present invention consists of a power supply and LED circuit arrangement for powering LED arrays such that single or multiple LED failures will have minimal affect on the utility of the LED array. The power supply consists of an analog or microcontroller-based feedback module with single/multiple feedback signals in series with a synchronous buck-boost converter followed by an optional filter and a LED array. The assembly utilizes the feedback signal, to modulate various parameters of the LED array, such as the output intensity, LED junction temperature, and chromaticity. The power supply can drive different circuit arrangements of LEDs including series, parallel, and combinations thereof. Typical feedback signals include LED current, temperature, and ambient luminance and contrast.

Abstract: The present invention consists of a power supply and LED circuit arrangement for powering LED arrays such that single or multiple LED failures will have minimal affect on the utility of the LED array. The power supply consists of an analog or microcontroller-based feedback module with single/multiple feedback signals in series with a synchronous buck-boost converter followed by an optional filter and a LED array. The assembly utilizes the feedback signal, to modulate various parameters of the LED array, such as the output intensity, LED junction temperature, and chromaticity. The power supply can drive different circuit arrangements of LEDs including series, parallel, and combinations thereof. Typical feedback signals include LED current, temperature, and ambient luminance and contrast.

Abstract: An improved method and apparatus for controlling the flow of any breathing gas such as oxygen through a cannula or "mask" to a person (patient, aviator, baby, miner, or diver) can be limited to the portion of the breathing cycle when the person breathes inward. This has the effect of reducing the consumption of breathing gas to at least half and possibly less. The result of this reduction of consumption is an extended life of the gas supply and a reduction of the cost per unit time. A bidirectional dynamic mass flow sensor senses the rate of flow of a gas through it and yields an output voltage proportional to mass flow and direction of gas movement. The measured dynamic flow signal is applied to a system controller which operates a flow controller. The system controller provides for indications of operation such as system failure and apnea, rate of flow, duration of flow, and total consumption; in addition, controls are provided to set the duration of gas flow in each breathing cycle.