Patent GB-702692-A (GB)
Title: Improvements in or relating to electrical pulse supply
IPC: H03K5/00
Filed: 1951-07-13
Abstract: 702,692. Automatic exchange equipment. STANDARD TELEPHONES & CABLES, Ltd. July 13, 1951 [July 19, 1950; July 19, 1950; July 19, 1950], No. 16663/51. Class 40 (4) [Also in Group XL (c)] A pulse generator comprises a number of identical pulse generators arranged to deliver pulses in synchronism to a common outlet so that, in the event of failure of one of the pulse generators, the output is not affected. The absence of a pulse from one of the generators causes a fault detector to disconnect the generator and signal a fault condition. Phase-correcting links are arranged between the generators to ensure synchronism of the output pulses. Sine wave oscillators 1, 11, Fig. 1, are maintained in synchronism by connection over device 3 and feed circuits 2, 2<SP>1</SP> producing pulse outputs. The pulses are fed to distributers 4, 41 having ten outputs, each input initiating an output pulse which is terminated by the succeeding input pulse. A pulse from distributers 4, 4<SP>1</SP> is applied through a pulse sharpening circuit 19, 19<SP>1</SP>, Fig. 3 (not shown). to distributers 20 ... 24 and 20<SP>1</SP> ... 241 arranged to give varying numbers of outputs, the resulting pulses occurring at the basic recurrence frequency divided by the number of outputs. These are fed out over contacts such as 35, 35<SP>1</SP> through buffer amplifiers 36. Fault detectors, Fig.. 5. The detectors 5, 16, 25 ... 29, Fig. 1, comprise cold-cathode gas-filled valves 63, 64 fed with pulses from the two chains, the grid of each valve being connected to the cathode of the other so that pulses occurring simultaneously are ineffective whereas an isolated pulse causes one or other of the valves to fire and operate relay 72 or 72<SP>1</SP>. The detectors 5 or 16, Fig. 1, open contacts 8, 8<SP>1</SP> or 9, 9<SP>1</SP> and detectors 25 ... 29 open the relevant contacts 35 or 35<SP>1</SP>, an alarm circuit also being completed. The key 76 may be operated to restore the fault detector circuit. Phase correcting links Fig. 7. Each of the distributers 4, 4<SP>1</SP> and 20 ... 24, 201 ... 24<SP>1</SP>, Fig. 1, comprises a ring of trigger pairs 108, 109 . . ., 108<SP>11</SP>, 109<SP>11</SP> . . . , phase correcting links 104 . . . . 107 corresponding to devices 6 and 30 ... 34 being provided between distributers A and B. A resistor 98 is arranged in the common cathode leads of the valves 108, 108<SP>11</SP> ... so that only one may be conducting at any instant. With the valves 108, 108<SP>11</SP> ... non-conducting, a positive pulse is received from the preceding trigger. pair and causes the pair 108, 109 to reverse and generate an output pulse which is ineffective on trigger pair 108<SP>11</SP>, 109". The next input pulse over terminal I resets the pair 108, 109 to terminate the output pulse on SA, and reverse the pair 108<SP>11</SP>, 109". If it is assumed that distributer B lags behind A, a pulse will reverse the pair 108, 109 before the pair 108<SP>1</SP>, 109<SP>1</SP>, is reversed by the pulse from the preceding pair so that a negative pulse is fed over link 105, 107 to reverse the pair 108<SP>1</SP>, 109<SP>1</SP>, the flow of current through resistor 98<SP>1</SP> resetting the preceding trigger pair so that the distributers A and B are in synchronism again.