| 摘要 |
334,516. Siemens Bros. & Co., Ltd., and Humphries, H. E. April 29, 1929. Divided on 334,205. Selectors responsive only to a particular code signal.-A device for opening and closing a circuit at a definite periodicity, say half a second, consists of a self-interrupting relay Z, Fig. 3, in parallel with a condenser QA and both in series with a choke or resistance W. The interruption of Z is preferably effected by a relay Y which is controlled by Z and itself controls the external circuit. The periodicity may be varied by a resistance, which may as shown at YA be in the discharge circuit of the relay or may be in the feed circuit W, or the condenser may be variable. The device is put in or out of action by a relay X (not shown). When this relay is de-energized Z is disconnected from QA, so as to release quickly, and QA is connected to a quickdischarge circuit YC. The elements QB, QC, YB are provided for spark quenching. A pair of relays A, B, Fig. 4, may be controlled by Y to cycle at twice. the period of Y. The first closure of y energizes A (i); when y opens, B (i) becomes locked in series with A (i); the second closure of y energizes a differential winding A (ii) to release A, B being held over (ii); the second opening of y releases B in readiness for a fresh cycle. Similarly A, B may control a second pair of relays which cycles at four times the period of Y. The device may be used for measuring the marks and spaces of a wireless alarm signal, as described in Specification 334,205. |
