Einrichtung zur Verstaerkung von Gleichspannungssignalen

摘要

1,165,502. Control of A.C. motors. GOSUDARSTVENNY NAUCHNO - ISSLEDOVATELSKY INSTITUT TEPLOENERGETICHESKOGO PRIBOROSTROENIA. 7 March, 1968, No. 11102/68. Heading H2J. [Also in Division H3] In a circuit of the type in which a D.C. signal is modulated on a carrier, amplified and then applied to a phase-sensitive device such as an electric motor, the modulator employs varicap diodes and modulation is effected upon low and high frequency carriers. The higher frequency can be of optimum value for the modulator and the low frequency optimum for the amplifier. As shown, the signal U 1 and lower frequency U 3 are applied to one diagonal of the modulator bridge and the high frequency to the others. The resulting double modulated high frequency is amplified by transistor 20, demodulated at 29 to produce the signal modulated lower frequency and this is reflexed to the base for further amplification before selection at 35 and application to a motor 33. When its input signal is zero only a doubled low frequency appears at the output and this is rejected by the output circuit 35. In an alternative modulator, Fig. 3, the high frequency is applied across one diagonal c, d and the low frequency in series between the diodes. In each circuit a balancing potentiometer may be provided.