| 摘要 |
1,048,035. Automatic voltage control. H. WELLHAUSEN.June 10, 1963 [June 9, 1962], No. 22963/63. Heading G3R. [Also in Division H3] In a voltage regulator of the series transistor type, the main transistor is protected against excessive power dissipation by a circuit which is connected across the collector and base of the transistor and which comprises the series combination of a resistor carrying the load current, a second resistor, and a voltage-dependent element. As shown, a voltage regulator supplying a load 2 includes a main transistor 1 and a resistor 9 connected between the collector of the transistor and the load. The end of resistor 9 remote from the collector is connected over a resistor 11 and a Zener diode 10 to the base of transistor 1. When a certain current is exceeded, the voltage drop across resistor 9 and the voltage drop across the collector/emitter circuit of transistor 1 are together sufficient to render Zener diode 10 conductive so that a base current flows in the transistor; on a further increase in current, e.g. on overload or short circuit, this base current causes the collector/emitter voltage to fall, so that most of the input voltage is dropped across the resistor 9 which is so dimensioned that the maximum transistor current is not exceeded even on short circuit. The transistor 1 is thus protected against damage; a fuse can be connected in circuit to protect the supply source. The regulator may include a further Zener diode connected across the collector/base circuit of transistor 1 and an amplifying transistor connected to the base of the transistor (Figs.4 and 6, not shown). |
