GB848497A - Improvements in or relating to electronic switching circuits - Google Patents

Abstract

848,497. Valve switching circuits. FERNSEH G.m.b.H. June 8, 1959 [June 6, 1958], No. 19518/59. Class 40(6). In an electronic switching circuit, Fig. 1, the individual signal paths 1, 2 each contain two sets of diodes (9, 10 or 17, 18) connected in series in the path and a capacitor 11 or 19 shunting the signal path at the junction of the diodes. The signals are fed to the switches through cathode followers 5, 13 and the diodes in each switch are oppositely poled so that one or other of the paths may be made conductive by connecting either a positive or a negative bias to the junction of the two paths by a switch 34. In practice the switch and bias potentials may be replaced by a suitable bi-stable switching circuit. The output selected is fed on to the grid of a valve 3, to which is also connected a clamp circuit to avoid switching transients in the output. In a second embodiment (Fig. 2, not shown) switching circuits as described above are used to select a signal from, say, channels I and II and another from channels III and IV. These two signals are then applied to a further similar circuit which again operates to select only one of the signals. In a further embodiment (Fig. 3, not shown) three inputs are connected to a common output terminal by switching circuits all having their diodes similarly poled. Switching potentials may be applied to the circuits to select any one of the signals, or alternatively signals may be combined by selecting two together.