Abstract: A permanent magnet generator having the unique feature of a speed proportionally adjusted air gap for self-regulation of coil output voltage over a wide range of operating rotational speed of a steam turbine to which the invention is coupled. The Permanent Magnet Generator rotor is supported by the turbine end shaft and the stator is supported by a bracket bolted to the turbine pedestal base or other rigid structure. The speed proportional air gap is accomplished through the use of a plurality of centrifugal flyweights in mechanical coupling to a spool piece under spring load and to corresponding rare earth magnets via linkage such that increasing rotor speed extends the flyweights outward from the rotor center of rotation and draws the rare earth magnets closer to the rotor center of rotation and thus increases the air gap.

Abstract: Microphones sample the sound output from the speakers of a sound amplification system. The resulting time domain analog signals undergo a Fast Fourier Transform which yields frequency domain signals representative of the intensities of the frequency bands which compose the sound. The intensities or levels of each band are compared to stored permissible level limits for each frequency band. Attenuators respond to signals indicative of band levels being exceeded by respectively attenuating the frequency bands to which they are tuned so the speaker output does not contain frequencies which exceed permissible limits. The time weighted permissible averages for each frequency are also integrated to provide for production of signals representative of the cumulative sound dosage.