Patent GB-190603239-A (GB)
Title: Improvements in Operating and Controlling Quadruplex Telegraph Systems; also applicable to other Telegraph Circuits or Systems.
Inventor: BERRY THOMAS HENRY
Filed: 1906-02-09
Granted: 1906-08-02
Abstract: 3239. Berry, T. H., and Berry, V. Feb. 9. Telegraphs.-Relates to improvements applicable primarily in quadruplex telegraphy but not necessarily limited thereto. In quadruplex telegraphy it is necessary that the receiving-instrument c o n - trolled by the non-polar relay that responds to large-volume currents shall not be affected by reversals of the largevolume currents that are intended to operate the polarized relay. According to this invention, the sounder or other receiving- instrument is screened from these reversals by a combination of relays interposed between it and the main line non-polar relay, the effect of which is to set the armature of the main line non-polar relay vibrating during the continuance of the largevolume current, and at the same time to hold the local circuit closed on the sounder &c. In the quadruplex system shown in the Figure, the reference letters a, A denote respectively the polarized relay and the sounder controlled by it ; b, B the non-polar relay and the sounder controlled by it ; M the polar key controlling through the relay P the supply of + or - current from the generators D, E ; N the non-polar key that controls the relay T, the function of which is to short-circuit the resistance 7 and at the same time to remove the normal leak through the wire s<1>, spring s, and resistance 19 and thereby to send the large-volume currents to line ; F the generator for operating the instruments in the local circuit ; and C, R the usual artificial line. The switch Y and the resistance 8 are for balance test purposes. The devices that are applied to the system in accordance with this invention are indicated in the diagram by heavy lines. The armature d of the non-polar relay b may be provided with a weak restoring spring 30, but the primary restoring device is a coil h, the circuit of which is controlled by a relay i arranged in series with one of the coils m of the relay that controls the sounder n. The other coil k is adapted to be supplied with current from the generator F through the resistance 5, but is normally shortcircuited by the armature of the relay i. When the large-volume current is sent to line from the transmitting-station by depression of the key N, the armature d is attracted. It thereby breaks the short-circuit to earth of the coils i, m, and the armatures e,f are attracted, the sounder n receiving current from the generator F through the resistance 6. The movement of the armature e closes the circuit of the coil h and thereby draws back the armature d, but, as the armature e has then broken the short-circuit on the coil k, the armaturef remains attracted even though the armature d falls back on its stop 15. As soon as the armature e falls back, the coil k is again short-circuited, but by this time the armature d has again been attracted and current is flowing in the coil m. The armature f therefore remains attracted as long as the large-volume current is passing through the relay b, and during this time the armatures d, e are in constant vibration. Any irregularities in the attractive force on the armature d due to reversals of the large-volume current are by this means rendered ineffective so far as the armature f and sounder n are concerned.