Patent GB-714700-A (GB)
Title: Improvements relating to transmitting apparatus for remote indicating systems
Inventor: WALKER DONALD FERGUSON
IPC: G08C19/34
Filed: 1951-08-01
Abstract: 714,700. Electrical selective signalling systems. FERRANTI, Ltd. Oct. 24, 1952 [Aug. 1, 1951], No. 18180/51. Class 40 (1). Transmitting apparatus for signals indicating at a receiver which conductor of a conductor array at the transmitter is electrically energised at a given moment comprises a common slider engaging the conductors singly but not bridging any two conductors, means for energising by intermittent current the particular conductor engaged by the slider, plural signal channels interconnecting the transmitter and receiver each including an input section linked to an output section by a two-state device having a first stable state wherein the output section is de-energised, and a second stable state wherein the output section is energised, coding means whereby each energised conductor is represented by an individual combination of energised channel input sections, re-setting means operated by the engagement of the slider with any conductor to trigger any two stage device from its second to its first stable state, and means whereby after each re-setting operation the two-state device of each channel whose input section is energised is triggered into its second stable state of operation. In a binary code remote signal transmission system an A.C. energised slider 11 selectively engagers seven circularly, disposed studs 10 respectively denoted by binary numbers 001, 010, 011, 100, 101, 100 and 111, the slider departing from one stud before engaging the next. Transformers 13‹; 13<SP>1</SP> and 13<SP>2</SP> corresponding to ascending powers of the binary scale have respectively 4 primary windings 14‹, 2 windings 14' and 1 winding 14<SP>2</SP> which are selectively connected to the respective' studs so that for each stud the windings which are energised correspond to the binary coding of such stud. The secondaries 15‹, 15',. 15<SP>2</SP> of the transformers are connected to the grids of respective coding thyratrons 20‹, 20<SP>1</SP>, 20' in series with a standing negative bias, and the thyratrons control relays 22‹, 22<SP>1</SP>, 22<SP>2</SP> which energise lines 23<SP>0</SP>, 23<SP>1</SP>, 23<SP>2</SP> leading to a remote receiver comprising binary decoding and display apparatus of the kind described in Specification 709,921. Selection by the slider of a particular stud energises the appropriate transformers 13<SP>0</SP>, 13<SP>1</SP>, 13<SP>2</SP> to strike one or more of the thyratrons, and energise one or more of the lines 23<SP>0</SP>, 23<SP>1</SP>, 23<SP>2</SP> in accordance with the binary code of the selected stud. For example, selection of stud 001 will energise primary 14<SP>0</SP>, secondary 15<SP>0</SP>, thyratron 20<SP>0</SP>, relay 22<SP>0</SP> and line 23<SP>0</SP>; while selection of stud 111 will energise primaries 14<SP>0</SP>, 14<SP>1</SP>, 14<SP>2</SP>, secondaries 15<SP>0</SP>, 15<SP>1</SP>, 15<SP>2</SP>, thyratrons 20<SP>0</SP>, 20<SP>1</SP>, 20<SP>2</SP>, and relays 22<SP>0</SP>, 22<SP>1</SP>, 22<SP>2</SP> and lines 23<SP>0</SP>, 23<SP>1</SP>, 23<SP>2</SP>. Appropriate indications are produced at the receiver, and when the slider is moved off a particular stud the appropriate combination of thyratrons remains struck, but immediately the slider contacts the next stud to energise the appropriate transformer primary combination, the resetting transformer 18 in the common primary return energises halfwave rectifier 31 on the 'first negative halfwave to develop a negative pulse across resistance 33 in opposition to the ,standing. positive bias on the grid of triode 38, which accordingly pulses positively the grid of the re-setting thyratron 41 in opposition to its standing negative bias. Synchronously with this pulse, its anode is pulsed positively from transformer 45 energised from the A.C. source, and the thyratron strikes, and through condensers 49<SP>0</SP>, 49', 49<SP>2</SP> pulses negatively the anodes of the coding thyratrons to quench those previously conducting and so cancel the combination. After a few cycles, condenser 32 charges up to a level at which no further negative pulses appear on the grid of valve 38, so that no further positive pulses are applied to thyratron 41, which is thus quenched on the next negative anode pulse. The coding thyratrons are then permitted to fire in accordance with the binary code of.the next selected stud, and the appropriate combination is transmitted to the receiver. Meanwhile condenser 32 has discharged through resistance 34 to prepare the re-setting circuit to quench the coding thyratrons on the next movement of the slider. The apparatus may be energised by intermittently pulsed currents instead of A.C. and is applicable to a system for transmitting, receiving and recording. The co-ordinated movements of a stylus as described in Specification 709,910. The thyratrons may be replaced by other devices triggerable from one stable to another and the quench pulses may be reversed in sense and applied to the cathode of the appropriate valves.