Electronic multiple phase DC tachogenerator arrangement - uses AC tachogenerator with phase sensitive amplifier and changeover circuit

摘要

An electronic multiple phase d.c. tachogenerator overcomes the problems of high cost, large size, and brush wear associated with such devices. This is achieved by using electronic circuitry in conjunction with an a.c. tachogenerator to produce a voltage proportional to the revolution rate and whose sign is dependent on the direction of rotation. A phase sensitive amplifier connected after the rectifying circuit, which can be electrical or electronic, detects the change in phase resulting from the change in rotation direction. A signal corresp. to the change in phase is fed to a change-over circuit which reverses the rectified tachogenerator voltage. The polarity reversal can either be reversed by an electronic amplifier with phase inversion or a relay, e.g. a rapid reed relay.