Patent GB-791892-A (GB)
Title: Improvements in or relating to arrangements for generating voltage impulses succeeding one another in time
IPC: H03K5/15
Filed: 1956-02-07
Abstract: 791,892. Automatic exchange equipment. SIEMENS & HALSKE AKT.-GES. Feb. 7, 1956 [Feb. 7, 1955], No. 3855/56. Addition to 718,155. Class 40 (4). [Also in Group XL (c)] An arrangement for producing a plurality of pulse trains having different phases comprises two groups of valves the anodes of one group being connected to one set of leads and the cathodes of the other group being connected to another set of leads, the leads being interconnected one from each set by a rectifier and the primary winding of a transformer so that the secondary may be caused to produce an output when the associated pair of valves is conducting. Fig. 1 shows two groups of hard valves T1a ... T1m, T2a ... T2n, the cathodes of the first group being connected to the anodes of the other group via rectifiers such as Rl1ma and transformers Trma. When pulses are applied simultaneously to the grids of T1m and T2a, these valves and rectifier Rl1ma conduct to pass a pluse through the transformer Trma. The pulses may be applied cyclically to the grids in each group. One pulse of one group may have duration equal to the whole period of the other group's cycle, or if m is prime to n, the pulses for each group may be of the same duration and spacing. Fig. 4 illustrates an arrangement using gas-filled triodes. In this case earthed resistors R1a ... R1m connected to the cathodes of valves V1a ... V1m and battery is connected via resistance R3 to the anodes of V2a ... V2n to ensure that valves in each group may fire independently of the condition of the valves in the other group. A conducting valve of either group is arranged to be extinguished on the firing of another valve in the group. Thus in group Vla ... V1m the charge on condenser C1m of a conducting valve V1m holds the cathode of V1m to such a potential that the drop in anode potential across R4 due to the firing of another valve is sufficient to extinguish Vim. Condenser C2a in conjunction with resistance R3 serves a similar purpose for valve V2a of the other group. When both valves V1m, V2a conduct, current through the associated transformer causes a pulse to be produced in the output winding. This pulse is, however, restricted in amplitude due to the presence of resistance R4 in the circuit and is eliminated by a suitably biased rectifier Rl4ma. However, subsequent to the completion of the path through the primary of the transformer the cathode follower T3 is pulsed by a suitably delayed pulse Ui to provide a low impedance shunt across R4, the consequent rise in current in the circuit producing a pulse in the transformer secondary winding sufficient to overcome the bias on Rl4ma. The condenser-resistance networks in the cathodes of V1a ... V1m may be replaced by networks in the anode circuits of these valves as in the case of valves V2a ... V2n. The use of a cathode follower such as T3 in the case of the hard valve circuit of Fig. 1 is also referred to for use in the case where the transformer output pulses are required to be of shorter duration than those actuating the valves V1a ... V1m or V2a ... V2n. The duration of the output pulse is then determined by the duration of the pulse applied to the cathode follower. An arrangement is also described (Fig. 3, not shown) in which the resistor R4, the cathode follower T3 and the condensers Cla ... Clm of Fig. 4 are omitted and a valve extinguishing device is included in the common anode supply of valves V1a ... V1m. This arrangement may be extended to the valves of the other group, the anode of each valve being connected via a resistor to a common supply line which is also provided with a valve extinguishing device.