Abstract: A circuit for monitoring the DC content of an AC waveform includes a differential amplifier having one input connected to the AC waveform and the other input connected to a capacitive-coupled network that eliminates any DC component in the AC waveform at the frequency being monitored. Additional circuitry is required to cancel any phase shift and reactance of the coupling capacitor. The output of the differential amplifier is a signal which represents the amplitude and polarity of the DC content.

Abstract: A three terminal replacement circuit for a Unijunction Transistor. The circuit simulates the characteristics and parameters of any UJT with appropriate selection of components. The circuit includes a first node having a voltage in accordance with a biasing circuit, a current conducting circuit for relating the voltage at the first node to a voltage at a second node and for conducting current from a terminal B2 to a terminal B1 through the second node in accordance with a resistor provided in that path, a first switching circuit which turns on when a voltage at a terminal E exceeds the voltage at the second node and a second switching circuit which turns on when the first switching circuit faces. The second switching circuit allows current to flow from the terminal E to the terminal B1 when turned on and changes the biasing circuit to lower the voltages at the first node, the second node and the terminal E.

Abstract: An unbalanced current detector for a three phase electrical system of the type including a current transformer (4, 6, 8) for each phase (.phi.A, .phi.B, .phi.C) and a burden resistor (16) which receives a rectified output of the current transformer is disclosed. The harmonic content of a rectified ripple voltage developed across the burden resistor (16) is applied to a filter (20) for extracting desired frequencies and rejecting other frequencies, and the filter output is applied to a level detecting and amplifying circuit (54) the output of which is applied to an indicator (77) to indicate an unbalanced current condition.

Abstract: A combination exciter/permanent magnet generator for a brushless generator system features a permanent magnet generator wound directly on the exciter structure, while allowing the permanent magnet generator and exciter to be functionally independent of each other. The arrangement is such that the permanent magnet generator provides sufficient voltage under a wide range of speed, load and temperature conditions to turn on power transistors included in a voltage regulator associated with the generator system and to insure adequate system self build-up to a required output voltage without increasing the size of the system as would otherwise be the case.

Abstract: A circuit for detecting a failed diode in a multiple diode rectifier bridge detects open or shorted diodes in both multi-phase, half-wave rectification and single or multi-phase full wave rectification arrangements and provides a failure signal for sounding an alarm or tripping the circuit to protect the load or power source as the case may be.