Patent GB-751905-A (GB)
Title: Improvements in or relating to methods of converting switching orders into impulse series by means of storage capacitors in tele-communications and especially telephone installations
IPC: H04Q3/42
Filed: 1954-06-21
Abstract: 751,905. Automatic exchange systems. SIEMENS & HALSKE AKT.-GES. June 21, 1954 [June 19, 1953], No. 18215/54. Class 40(4). To compensate for the fact that the potential of a capacitor does not rise by equal increments at successive connections to another capacitor previously charged, the second capacitor is charged at a higher voltage so that the more linear part of the potential/successive impulses curve is used. The invention is applied to an operator's or subscriber's keysender. First embodiment, Fig. 4. When the group selector 1GW is seized, feed bridge relays A, B operate to the subscriber's loop and energize relay C to seize the storage circuit. Relays P and Q also operate. The subscriber then depresses a digit key T1-T0, which in a manner not shown restores A, B to release Q slowly. During the falling-off time of Q a voltage of 100 v. is applied to potential divider Sp so that the depressed key applies an appropriate part of that voltage to storage capacitor Cp1. During the release time of B the rotary selector Dl makes one step to disconnect Cp1 from the speech wires. Release of Q re-energizes A to re-operate C. When the key is released B also pulls up to re-energize Q. Subsequent digits are stored in capacitors Cp2 . . . Cp11 in like manner. The stepping of selector D1 releases relay Vh to cause selector D2 to step so connecting the capacitor Cp just charged to the grid of valve C3m, which cuts off to release P, which then operates relay V. V re-energizes Vh and impulse relay J. J and H then interrupt one another, J also impulsing the first group selector. At the same time contact i3 connects bleeder capacitor Cs charged to 400V to compensation capacitor Ck, each such connection raising the voltage of Ck by 10V. At each response of H, Ck is connected in series with storage capacitor Cp1, and when capacitor Ck has been charged an appropriate number of times by relay J the grid bias is tracked off and relay P pulls up again to stop the impulse emitting circuit. The falling-off times of V and Vh determine the inter-digital pause. Release of Vh steps selector D2 so that the next digit may be sent, but if no further storage capacitor has been charged Vh remains energized since D2 has overtaken D1. Second embodiment, Figs. 5 and 6. If two bleeder capacitors Cs1, Cs2 are used separately, Fig. 5, or in series, Fig. 6, half the voltage, i.e. 200 V, may be used. In Fig. 5 an auxiliary relay Jh discharges the bleeder capacitor Cs1 through the compensation capacitor Ck1 after the charging of compensation capacitor Ck2. Third embodiment, Fig. 7. The compensation capacitor Ck is initially charged and is discharged step by step by bleeder capacitor Cs. Storage capacitor Cp is connected to a further capacitor Cg of like polarity and opposing Ck. Fourth embodiment, Fig. 8. In this case the potentials tapped off by the keys are graded to overcome the curve of the potential/pulse emitted graph, and a maximum source potential of 60V is used with the compensation capacitor charged by the bleeder capacitor to three times the operating voltage by an artificial circuit. This system is suitable for an operator's keysender. Depression of a key energizes E to charge the storage capacitor Cp1 to the keyed voltage. D1 and D2 then step, the latter connecting the storage capacitor to the grid of valve C3m and energizing V. The storage capacitor is thus put into series with compensation capacitor Ck to release P. V energizes Vh and impulse relay J energizes and self-releases slowly, operating auxiliary relay Jh at each energization. Jh reverses the polarity of bleeder capacitor Cs and discharges it into compensation capacitor Ck at each impulse to raise the potential on the grid of valve C3m step by step. Fifth embodiment, Fig. 9. When one of the storage capacitors Cp1-Cp6 has been charged relays Vh and V (not shown) energize to disconnect a charged compensation capacitor Ck from battery and earth and connect the storage capacitor aided by the 60V of the compensation capacitor to the grid of tube C3m. A selfinterrupting circuit (not shown) vibrates contacts h to emit impulses and back off the grid voltage in steps by repeatedly connecting bleeder capacitor Cs to the compensation capacitor Ck. When the tube conducts relay P stops the self-interrupting circuit. The prior state of the art is represented by a reference to German Specification 697,625.