TACHOMETER AND METHOD FOR OBTAINING A SIGNAL INDICATIVE OF ALTERNATOR SHAFT SPEED

摘要

An improved tachometer which includes an alternator connected to a shaft whose speed is to be measured and which generates an alternating voltage. Electrical circuits perform a non-linear operation on the generated alternating voltage and produce a unidirectional output proportional to the speed of the shaft by order-independent iterative pairwise binary operations. One embodiment of electrical apparatus for performing such operations is a sine wave generator followed by square law operations on the generated voltages followed by an operational summer. Another embodiment includes a square wave generator followed by bridge rectification of the square waves to produce a unidirectional signal followed by a star or tree of diodes to produce an auctioneering circuit which passes the largest rectified voltage. Another embodiment of this invention is a tachometer in which a velocity signal is derived from computations based on the alternator terminal potentials and currents.