Circuit arrangement for deriving a direct voltage from the mains alternating voltage
First Claim
1. A circuit arrangement for deriving a direct voltage from an alternating voltage, said circuit arrangement comprising:
- two input terminals,two output terminals one of which is connected to one of the input terminals,a switching transistor whose main current path is connected between the other input terminal and the other output terminal,a control circuit for controlling the switching transistor, which control circuit includes a thyristor which is connected via a first resistor between the two input terminals, a node between the first resistor and thyristor being connected to a control electrode of the switching transistor, anda time-determining circuit comprising a series arrangement of a second resistor capacitor and a trigger element connected between a gate terminal of the thyristor and a node between said second resistor and capacitor, characterized in that the trigger element comprises a diac, in that the other input terminal is connected to an alternating voltage terminal via a rectifier diode arranged in the forward direction with the main current path of the switching transistor, in that the series arrangement of second resistor and capacitor is connected between the alternating voltage terminal and the one input terminal and in that a diode is coupled across the capacitor in such a way that said diode conducts during the periods when the rectifier diode is blocked.
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Accused Products
Abstract
A circuit arrangement for deriving a direct voltage from an alternating voltage, particularly the mains alternating voltage. The circuit arrangement includes a switching transistor (T1) whose main current path is connected via a rectifier diode (D1) between the input and the output and whose control electrode is controlled by a thyristor (Th). The gate electrode of the thyristor is connected via a diac (D3) to a time-determining circuit comprising a series arrangement of a resistor (R1) and a capacitor (C1). A diode (D2) is arranged across the capacitor in such a way that the diode (D2) conducts during the periods when the rectifier diode (D1) is blocked.
5 Citations
17 Claims
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1. A circuit arrangement for deriving a direct voltage from an alternating voltage, said circuit arrangement comprising:
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two input terminals, two output terminals one of which is connected to one of the input terminals, a switching transistor whose main current path is connected between the other input terminal and the other output terminal, a control circuit for controlling the switching transistor, which control circuit includes a thyristor which is connected via a first resistor between the two input terminals, a node between the first resistor and thyristor being connected to a control electrode of the switching transistor, and a time-determining circuit comprising a series arrangement of a second resistor capacitor and a trigger element connected between a gate terminal of the thyristor and a node between said second resistor and capacitor, characterized in that the trigger element comprises a diac, in that the other input terminal is connected to an alternating voltage terminal via a rectifier diode arranged in the forward direction with the main current path of the switching transistor, in that the series arrangement of second resistor and capacitor is connected between the alternating voltage terminal and the one input terminal and in that a diode is coupled across the capacitor in such a way that said diode conducts during the periods when the rectifier diode is blocked. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An AC/DC circuit comprising:
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first and second input terminals for connection to a source of AC voltage, first and second output terminals, a rectifier diode and a switching transistor connected in series circuit between said first input terminal and said first output terminal, first means connecting said second output terminal to said second input terminal, means including said rectifier diode for coupling a thyristor to said input terminals, second means connecting a first circuit node between the thyristor and the rectifier diode to a control electrode of the switching transistor, a timing circuit comprising a series arrangement of a resistor and a capacitor connected across said input terminals, a diac connected between a gate electrode of the thyristor and a second circuit node between said resistor and capacitor, and a diode connected in parallel with the capacitor and with a polarity such that said diode conducts during periods when the rectifier diode is non-conductive, whereby initial capacitor voltage is the same at the start of each half cycle of AC voltage for which the rectifier diode is conductive. - View Dependent Claims (16, 17)
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Specification