Abstract: An automatic calibration system for signal amplifier circuits uses a single complex power signal to replace the formerly used four separate sinewave frequencies and a square wave signal. In the illustrated embodiment of the invention, the power signal is recorded on a magnetic tape and is played back through reproduce equalizer circuits which apply the reproduced signal to a tracking frequency converter to produce an amplitude measurement of each of the preselected frequency components forming the complex power signal. The amplitude measurements are referenced to the power signal's actual harmonic content to enable an adjustment of the equalizer circuits to produce a minimum error in the playback signal. A bandpass phase response measurement is also performed on the reproduced signal by comparing the phase difference between the reproduced signal and a synthesized power signal after the amplitude compensation produced by the amplitude measurements.

Abstract: A centrifugally controlled differential brake uses a plurality of disc brake pads which are urged against a non-rotating braking surface. The disc brake pads are each slidably mounted on a respective one of a plurality of first support rods and spring loaded to a position at one end of the corresponding rods. The other ends of the plurality of support rods are attached to a hub on which the rods are radially arranged and equally spaced. The hub is connected to a shaft to which a braking torque is to be applied. Each of the brake discs is connected by a connecting link to a respective one of a plurality of centrifugal weights which are each slidably mounted on a respective one of a plurality of second support rods. The second support rods are radially attached to the hub and equally spaced with each of the second rods being aligned diametrically opposite a respective one of the first rods.