Abstract: A highly efficient line transient protection circuit is provided for high power loads that are designed to operate through a high line transient. The transient protection circuit for high power loads is provided with a primary leg circuit, a load circuit and a secondary circuit. The load circuit may be a switching regulator circuit, a load circuit containing an oscillator, a push-pull circuit, a boost converter circuit, a buck converter circuit or the like. The transient protection circuit is provided with a simple driver circuit to turn on a bypass n-channel MOSFET. It operates at a higher efficiency; I.E., conduction losses are minimized during normal input voltage conditions. Furthermore, the transient protection circuit provides a programmable voltage clamp which is implemented through selecting zener diode VR1. The transient protection may be used to protect medium to large current circuits from line transients.

Abstract: Paralleled DC power supplies each comprise a half-bridge, resonant inverter (19-23) feeding a converter (25-28) connected to a common load 8. Current mode control (50-54) is provided (36) through a PWM IC (30) to which the output voltage (31) is fed back. Inverter capacitor imbalance is corrected (52, 55-59). Load sharing (71) is accommodated with offset compensating bidirectional buffer amplifier circuits (65-70, 74-76).

Abstract: A light unit has a strobe operated flash tube and a non-strobe peripheral lamp immediately beneath the flash tube; a switch can turn the unit off, operate either light or enable the pilot of an aircraft to signal the light unit to operate the flash tube or to turn off the flash tube and operate the non-strobe peripheral lamp, by means of a radio receiver having a local oscillator midway between two standard distress frequencies. The light unit may have infrared or other color lenses. A ribbon assists establishing a pattern of light and/or colors to mark a landing site and indicate wind direction.

Abstract: A remote load (14) is powered by a power supply 12 in response to a PWM IC (9), the error amp (10) of which is responsive to a voltage feedback signal on remote sense leads (19, 20) from the load. Remote sense leads (19, 20) are applied through a polarity correcting bridge (23) to the input (11) of the error amp (10). To compensate for broken leads, when the output of the bridge (28) falls below a threshold voltage (32), a switch (34) operates to connect the input of the error amp to the output (16, 37) of the power supply, locally.