Patent GB-190200750-A (GB)
Title: Improvements in Wireless Telegraphy
Inventor: BROWN SIDNEY GEORGE
Filed: 1902-01-10
Granted: 1903-01-10
Abstract: 750. Brown, S. G. Jan. 10. Wireless telegraphy; induction coils.-Single-point coherers, relays, vibrating paper carriers, induction coils, and call arrangements are described for wireless telegraphy. Fig. 4 shows a modification of a form of coherer described in Specification No. 19,710, A.D. 1899 ; the air and earth lines are connected to a stationary point S, and a disc I' on a vibrating diaphragm. The point and disc may be made of steel, nickel steel, nickel zinc, cadmium, aluminium, mercury, or other metal. The diaphragm is acted on constantly by an electromagnet N, excited by an intermittent current from a battery B" and an automatic interrupting-reed V, the circuit being closed by a resistance U, which normally weakens the current so that the diaphragm does not vibrate. When a signal is received, the coherer S, P closes the circuit of an inductivelyshunted battery B', through the pivoted coil C of a magnetic relay ; the coil C carries a tongue, not more than one-quarter of an inch long, which then short-circuits the resistance U, increasing the current in the electromagnet N so that this vibrates the diaphragm and effects de-coherence. At the same time, the relay arm opens the circuit of a battery Z' and a relay O, so that this closes a circuit containing a call-bell G. In a modification of this arrangement, when the relay C is actuated, it closes a circuit through a bell and an electromagnet ; the armature of the latter then raises a lever, which carries the coherer screw, to effect de-coherence. In another modification of the same arrangement, the vibrator V is dispensed with ; when the relay arm moves, it closes a battery circuit containing the de-cohering-electromagnet N, and the electromagnet of a call-bell or a Morse recorder, shunted by a condenser. Choking coils are interposed between the coherer and the relay. In another construction, the lower coherer contact is carried by a fork, which also carries a contact spring, and is maintained in vibration electromagnetically ; the coherer screw is carried by a pivoted lever, weighted to maintain imperfect contact. A siphon ink recorder may be operated directly by the current from the coherer ; the paper travels over a curved support, carried by a reed, which is vibrated electromagnetically in the direction of the length of the paper, to reduce friction. A telephone receiver T, Fig. 4, may be connected to the ends of the inductive shunt of the battery B<1>. An induction coil for sending purposes has its secondary coil supported by a wooden frame, and separated by an open space from the primary coil, the whole being immersed in oil ; a spring contact-breaker and a hand-switch, in series, are shunted by a condenser. The Provisional Specification states that the secondary coil may be in halves, for connection in parallel or series. It also describes a switch consisting of an ebonite rectangle, hinged to a support at one end, and carrying the air and earth terminals at the other, to make contacts with terminals on ebonite pillars for sending or receiving.