GB1128198A - Improvements in or relating to hybrid electric circuit arrangements - Google Patents

Abstract

1,128,198. Automatic exchange systems. SIEMENS A.G. 28 March, 1967 [29 March, 1966], No. 14005/67. Heading H4K. A four-wire/two-wire time division multiplex conversion is made by pulsing switch Sx1 to effect resonant transfer between the storage capacitor of the two-wire line (not shown) and the storage capacitor Cx1 of the GO channel Vx1 of the four-wire line Vx, the switch Sx2 being subsequently pulsed to effect resonant transfer between the capacitor Cx1 of the GO channel Vx1 and the capacitor Cx2 of the RETURN channel Vx2. The switch Sx2 may be controlled by the same pulse that operates Sx1 but after the delay introduced at #t. With the connections of switches, Sx1, Sx2, as shown, the switches have to be held operated for different periods of time to achieve resonant transfer as the inductances for each transfer differ. If, however, Sx1 is connected to switch a tapped portion and not the whole of inductor Lx to the two-wire line, while Sx2 switches the whole of Lx (Fig. 2, not shown), the operating time of the switches can be made the same. The storage capacitors may be associated with auxiliary series-connected capacitors charged over transistors as described in Specification 1,034,560 (Fig. 3, not shown). The GO and RETURN channels of a number of four-wire lines may be multiplexed to the same pair of switches Sx1, Sx2 (Fig. 4, not shown). The switches Sx1, Sx2 may be provided in the manner shown in Fig. 6 where the highway has legs M1, M2 biased above and below earth so as to normally cut off diodes 1D1, 1D2 in switch Sx1. A pulse to winding Pd of transformer Ud forward biases the diodes 1D1, 1D2 to gate the highway to the GO channel Vx1 for the duration of the pulse. When the pulse ends, reverse potentials appear for a period in the transformer secondary Sd and these forward bias the normally cut-off diodes 2D1, 2D2 comprising the switch Sx2. The RETURN channel Vx2 is consequently connected to the GO channel Vx1 as is required.