| 摘要 |
502,573. Valve amplifying systems. STIELTJES, F. H. Sept. 23, 1937, No. 25872. Convention date, Sept. 24, 1936. [Class 40 (v)] An electrical transmission system comprises two or more forwardly acting amplifier paths and a single negative feed-back path between the common output and input circuits, whereby the overall amplifier characteristic is prevented from varying substantially in the event of breakdown of one of the amplifier paths. Fig. 1 shows a normal type of line amplifier in which the output voltage across resistance 1 is fed back in phase opposition to the input. The forwardly acting path (rectangle B) is duplicated as at B1, B2, Fig. 2, one being switched in on failure of the other by a system of inert and energized relays actuating switches SW1, SW2, SW3. Alternatively, the input and output circuits of the paths may be permanently in parallel, Fig. 2 (not shown), or in series, Fig. 6 (not shown), or in series-parallel. Voltage feed-back may be employed instead of the negative current feed-back shown in Fig. 1, Fig. 5 (not shown), and the amplifier paths may be constituted by modulator units, Fig. 4 (not shown). Signals may be provided to show the number of amplifier paths in use. |
