A frequency measuring device can measure the frequency of a noisy power system at high speed. The circuit may include first and second portions which, respectively, provide first and second voltages to the ignitor. The machine also includes rotor windings that are configured to be selectively coupled to either an exciter or a plurality of commutator segments, and DC brushes that are selectively moveable into, and out of, electrical contact with the commutator segments, to thereby electrically couple and decouple a DC power source to and from, respectively, the rotor windings. Compare the new inventory of information to a current inventory of information.