GB888306A - Improvements in or relating to transistor amplifier circuits - Google Patents

Abstract

888,306. Transistor switching circuits. SIEMENS-SCHUCKERTWERKE A.G. June 26, 1959 [June 30, 1958], No. 22019/59. Class 40(6). A switching circuit comprises an input transistor having its emitter-collector path connected in parallel with the collector-base path of the succeeding transistor, the parallel portion of the succeeding transistor circuit including a resistor arranged to carry the collector current of that transistor and less in value than the collector-emitter load resistor. In the Figure, an. input is applied at 7a and 8a or 9a and 8a to render a normally non-conducting transistor 6a conducting. This causes the succeeding transistor 3a to conduct, the collector currents of both transistors passing through the load 5. In order to ensure that the collector-base circuit of the succeeding transistor falls to a low value, less than that of the emitter collector voltage of transistor 6a, a resistor 4 is included in the collector path of transistor 3a. Transistors 6a and 3a may be of opposite conductivity type (Fig. 3, not shown) and transistor 3a may be replaced by two transistors connected in parallel with separate or a single collector resistor and with emitter resistors to equalize the transistor currents (Fig. 4, not shown). In addition, rectifiers may be connected between terminals 7a and 8a, and 7a and 9a in order to control the reverse voltage applied to the emitter junctions of transistors 7 and 3a.