GB601508A - Electronic switching system - Google Patents

Abstract

601,508. Thermionic distributers. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Oct. 18, 1945, No. 27398. Convention date, Sept. 16, 1943. [Class 40 (iii)] [Also in Group XL (c)] In a switching system for connecting one or more inlets to any one of one or more outlets, a switching device is provided selectively to apply anode potentials to amplifiers connected between the inlets and outlets. The Figure shows an arrangement for switching signals from input terminals 121 and 123 to either of output terminals 143 and 144, in which a pair of thyratrons 166 and 167, arranged so that only one can be conducting at any instant, are each connected to short when conducting the H.T. supply to one amplifier in each of the pairs of amplifiers 116 and 118, amplifier pair 116 comprising for example push-pull stages 196- 197 and 198-199 fed from a phase splitter 119 common to the pair and driving further stages 132, 138, the anode potentials of which are fed to output stages 147 and 156. The anode circuits of valves 132 and 138 are common with the corresponding stages 139 and 141 in the pair 118. The connections of the amplifier inputs and outputs are such that signals from terminal 121 go to terminals 143 or 144 while those from terminal 123 go to terminals 144 or 143 according as thyratron 166 or 167 is conducting. Since the switching potentials appear as in-phase variations at the anodes of the push-pull stages, no resultant voltage change is applied to the next stages. The thyratrons may be fired by impulses fed directly from terminals 173, 174, 191 or through amplifier 177 from terminals 181 or 182. One input and one pair of amplifiers may be omitted as in Fig. 2 (not shown), or one amplifier in each pair and the corresponding output terminal may be omitted as in Fig. 1 (not shown). Relay or hard valve circuits may be substituted for the thyratrons, which may be fired by impulses or by a substantially sinusoidal waveform. The thyratrons may be connected in a selfrestoring circuit so that a single-ended switch input may be used.