Selbstschwingender Transistor-Generator in Gegentaktschaltung

摘要

949,790. Converting. PHILIPS ELECTRICAL INDUSTRIES Ltd. Nov. 9, 1960 [Nov. 12, 1959], No. 38496/60. Heading H2F. [Also in Division H3T] A push-pull transistor oscillator, more particularly for a D.C. to D.C. converter, has a tuned centre-tapped collector winding for determining the oscillation frequency and a small inductance connected in the collector circuits so as to prevent the transistors, when conducting, from short circuiting the tuning capacitance and to provide a switch-off pulse for the bases. Fig. 1 shows a tuned push-pull oscillator of the basic type described in Specification 909,969, but not in accordance with the invention. The main feedback via the transformer is supplemented by feedback via C.R. circuits 5, 6, 16, 17 which provide pulses, leading in phase, to offset the effect of charge storage in the transistors due to operating near the α1 cut-off frequency. A small inductor 23 is added to the common portion of the collector circuit to prevent a too rapid rise in collector current when the transistors are switched on. The resulting pulse across the inductor reduces the feedback voltage and lengthens the pulses applied to the base by the feedback at the leading and trailing edges. In Fig. 2, the small additional inductors are provided in each collector circuit and, in accordance with the invention, windings 24 and 241 are coupled to these to provide cut-off pulses at the bases In addition, the capacitors 5, 6 of the C.R. circuit are transferred to the secondary windings. In a further embodiment (Fig. 3, not shown), the small inductor is connected in series with the common portion of the emitter circuits and the feedback windings are coupled in series with the base circuits. A rectifier may be connected to the output terminals to provide a D.C. supply. Specification 909,969 is referred to.