Stabilisierter Transistoroszillator

摘要

946,418. Automatic voltage control. PHILIPS ELECTRICAL INDUSTRIES Ltd. April 21,1961 [April 25, 1960], No. 14543/61. Heading G3R. [Also in Divisions G1, H2 and H3] An oscillator having at least one transistor with feedback between the emitter-collector circuit and the base circuit, and an overflow circuit coupled to the base, comprising a rectifier biased to conduct only when the oscillation amplitude exceeds a threshold value, is characterized in that the feedback voltage is stepped up before being applied to the threshold circuit. In order to protect the oscillator against over voltage when lightly loaded a converter, Fig. 1, comprising two transistors 1, 11 having their emitter-collector circuits coupled to their base circuits by windings on transformer 2, is provided with overflow circuits which comprise diodes 9, 91 connected to a source of reference potential formed by the parallel combination of capacitor 10 and Zener diode 11 and the feedback voltage applied to these circuits is stepped up by windings 3, 31 coupled to the base winding. The output from the circuit is derived from a further transformer 4. In a second embodiment, Fig. 2, providing a D.C. output, the Zener diode is replaced by the emitter-collector path of a transistor 11, the base of which has its potential determined by a resistor 12 and non-linear resistance 13 e.g. a Zener diode. A resistor 14 is added to ensure that the diodes 9, 91 are cut off when starting. In a third embodiment Fig. 4 the amplitude of the output at the terminals 81 is stabilized by making the resistor 13 a light sensitive resistor, and mounting it in a can together with a lamp 18 which is connected in series with a variable resistor 19 to an output winding on the transformer. The lamp thus provides a feedback control which depends on the amplitude of the output, the level at which the output is stabilized being adjusted by the resister 19. A further resistor 15 is provided which together with the resistor 14 constitute a potential divider so that only part of the voltage of source 7 is applied as initial cut-off bias to the diodes 9, 91. The oscillators are of the saturation type, either of the transformers 2 or 4 being saturable, or the transistors 1, 11. Specification 769, 445 is referred to.