Improvements in or relating to electrical circuits employing static electrical switches

786,056. Electric digital - data - storage apparatus. STANDARD TELEPHONES & CABLES, Ltd. March 11, 1955 [March 19, 1954], No. 8109/54. Addition to 663,574, [Group XXXIX]. Class 106 (1). A pattern moving shifting register representing data by the conductive state of transistors is characterized in that each stage contains only one transistor which can be either on-conducting heavily, or off-conducting slightly. Each point contact transistor, X2 has its emitter connected to a supply line - P normally at - 3v. and over which negative stepping pulses are applied, its collector connected via a load R21 to a - 20 v. supply line and its base to an earth line via diodes G13 and G12, the latter of which is also connected to a stabilizing 50 v. supply line via a resistor R13 and forming with the resistor the base load over which feed-back takes place. At the leading edge of a negative shift pulse any transistor in its on state, say X2, is cut-off causing the potential of the upper plate of a condenser C22 to become more negative than - 3v. At the end of the shift pulse when the voltage on line - P returns to - 3v. those transistors, X3 in particular, adjacent to a preceding trigger that was on. have their bases more negative than - 3v. which is the emitter potential. They are thus caused to go on and the pattern is stepped one stage. A diode G21 prevents positive pulses being transmitted from transistor X2 to transistor X3 and a diode G13 prevents transient current due to the discharge of C22 flowing in the common emitter line. A modification shows how parallel to serial and vice versa conversion may be effected.