Improvements in or relating to sequential switching apparatus

861,727. Transistor switching circuits. MICROCELL Ltd. Aug. 26, 1959 [Aug. 26, 1958], No. 27371/58. Class 40(6) Apparatus for rendering a number of circuits conducting for a short time interval in succession comprises a number of transistors to which a sloping waveform is applied so as to render the transistors conducting successively, means being provided in the emitter collector path of each transistor which interrupts the path when the transistors conduct. In the figure transistors 10, 11, 12 are biased by resistors 20 to 24 in increasing amounts so that a sawtooth wave applied from a circuit (such as a "boot strap" circuit 26) renders the transistors conducting in succession. The conduction of each transistor operates one of relays 13, 14 and 15, the corresponding contacts of which 17, 18 and 19 open circuit the emitter circuit so that the relays are de-energized after a short time interval. The relays however may be maintained operated by a holding circuit or latching arrangement. The relays may be replaced by fuses which blow when the circuits conduct. In addition, the biasing circuits may be omitted and the sawtooth wave applied to successive transistors through an increasing number of diodes so that due to the forward contact potential of the diodes or their reverse zener potential the transistors conduct in succession (Fig. 2, not shown).