| 摘要 |
516,429. Electromagnetic relays. JACKSON, H. May 26, 1938, No. 15684. [Class 38 (v)] In a relay system suitable for connecting a radio receiver to A.C. mains 4 when any one of a number switches 9 situated at loud speakers is operated, the switches 9 are adapted to impose or remove a short-circuit from a rectifier 5 which is connected across a winding 2 of a relay, and the winding 2 acts as the secondary of a transformer the primary 1 of which is continuously energized by the A.C. supply 4. In the form shown the rectifier 5 is normally short-circuited and the winding 1 is unable to operate the relay. Opening of a switch 9 causes direct current to pass through winding 2 and the relay operates to close contacts 3 and connect up the receiver. In a modification the switches 9 are in parallel instead of in series.
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