Abstract: A fluorescent ballast and control circuit having a drive signal generator responsive to a drive frequency control signal, the drive signal generator providing a ballast drive signal having a drive signal frequency proportional to the drive frequency control signal. A fluorescent ballast is driven by the ballast drive signal and has an output voltage coupled to drive a fluorescent lamp load. The fluorescent ballast circuit provides a change in the output voltage applied to the lamp load in response to a change in the ballast drive signal frequency. A means for monitoring the brightness of the lamp load develops a brightness signal that characterizes the brightness of the lamp load. A signal conditioner responds to the brightness signal and to a reference signal and provides and adjusts a drive frequency control signal to keep the brightness signal substantially constant.

Abstract: A fluorescent ballast and control circuit having a drive signal generator responsive to a drive frequency control signal, the drive signal generator providing a ballast drive signal having a drive signal frequency proportional to the drive frequency control signal. A fluorescent ballast is driven by the ballast drive signal and has an output voltage coupled to drive a fluorescent lamp load. The fluorescent ballast circuit provides a change in the output voltage applied to the lamp load in response to a change in the ballast drive signal frequency. A means for monitoring the brightness of the lamp load develops a brightness signal that characterizes the brightness of the lamp load. A signal conditioner responds to the brightness signal and to a reference signal and provides and adjusts a drive frequency control signal to keep the brightness signal substantially constant.

Abstract: A fluorescent ballast control process for a fixed and variable frame rate method of driving a fluorescent ballast to control the brightness of a fluorescent lamp load over a brightness range. The fixed frame rate process uses a fixed number of pulses in each frame. The variable frame rate process uses a variable number of pulses in each frame. When the two processes are combined, the control is gradual in response to a user control signal (BRIGHT). The transition from the fixed to the variable frame rate control process occurs seamlessly as the variable BRIGHT×BRIGHT×OVER where BRIGHT×OVER is calculated.

Abstract: A fluorescent ballast control process for a fixed and variable frame rate method of driving a fluorescent ballast to control the brightness of a fluorescent lamp load over a brightness range. The fixed frame rate process uses a fixed number of pulses in each frame. The variable frame rate process uses a variable number of pulses in each frame. When the two processes are combined, the control is gradual in response to a user control signal (BRIGHT). The transition from the fixed to the variable frame rate control process occurs seamlessly as the variable BRIGHT=BRIGHT×OVER where BRIGHT×OVER is calculated.

Abstract: A power supply Active Bleed Voltage Balancing Circuit for attachment to the outputs of a regulated power supply having at least a first output and a second output to shunt load power from an output that has become unloaded and has an output voltage that is rising past an acceptable limit. The Active Bleed Voltage Balancing Circuit has an inductor with a first terminal coupled to the first power supply output. The second output voltage exceeds the first output voltage. An oscillator driven totem-pole driver alternately drives the inductors second terminal to the power supply second output and then to ground. The duty cycle ratio is adjusted to equalize the volt-seconds applied in each position. An alternative circuit uses a multiple winding inductor with a 50/50 duty cycle and with balancing achieved by adjusting the turns ratio to equal the ratio of the output voltages.

Abstract: A bi-directional flyback converter (30), as regulated by control circuitry (34), is used to maintain power from a capacitor (36) to aircraft electronics (20) when power from a ground source through bus (12) is switched by a switching relay (16) to the aircraft source through bus (14). When the aircraft is on the ground and prior to engine start up, power is fed through bus (12). Such maintenance of power is necessary during switch-over from the ground to the aircraft power source, to avoid any transitory interruption of power. In operation, once the proper voltage is reached, the circuit turns off, minimizing power consumption. When the input power drops, the bi-directional converter acts as a voltage source, keeping the supply input voltage at a minimum set point by using the energy stored in the capacitor. An anticipation circuit turns on the circuit before power is actually needed so that the response time is instantaneous.