| 摘要 |
878,061. Magnetic amplifiers. COMPAGNIE INDUSTRIELLE DES TELEPHONES. May 28, 1959 [June 2, 1958], No. 18224/59. Addition to 871,623. Class 40 (9). A magnetic amplifier comprises a winding a on a saturable core fed by alternating current, the output of the winding passing through a rectifier Rd to be fed across the base resistor R 2 of a transistor T whose collector current feeds the load Rc. The magnitude of the negative half cycle current I m from the core is shown in Fig. 3 in terms of the D.C. control ampere-turns N c , I c of the control windings b.c. When I m exceeds a threshold value U o / R 2 the emitter current I e flows, the corresponding curve being shown in Fig. 5. The collector current I s (and hence the load current) follows a similar curve with the exception that the current is limited to a value I 1 which occurs when the collector and base achieve the same potential. The characteristic of the amplifier is thus as shown at G 4 , Fig. 6. Bi-stable operation may be effected by the introduction of positive feedback via winding d. A resistance may be inserted between point F and the collector of the transistor to prevent excessive discharge current from the smoothing condenser Ca from damaging the transistor.
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