| 摘要 |
897,836. Automatic speed-control systems. BOLKOW, L., [trading as BOLKOW-ENTWICKLUNGEN KOMM.-GES]. Nov. 18, 1960 [Nov. 24, 1959], No. 39720/60. Class 38 (4). [Also in Group XL (c)] In a supply system for a battery-driven constant speed motor M, e.g. for a portable recording machine, warning is given of low battery voltage V by an indicator L. The motor is controlled by a centrifugal switch S (closed at low speed) and a transistor Tr1 While the switch is closed voltage is applied also to a resistance-capacitance network R2, C2 but normally this is for a period below the time constant of the network so that negligible voltage appears at the base of a second transistor Tr. However, with falling battery voltage the ratio " closed to open " for switch S increases (to maintain the motor speed constant) so that the voltage on the base of Tr rises. Eventually the transistor conducts and the indicator L, e.g. a lamp, is operated. |
