| 摘要 |
PURPOSE:To make output power constant without depending on a change in input voltage or output load by controlling the charging time of a capacitor to determine a starting point of high frequency oscillation of one of transistors which alternately turn on, in correspondence to the value of a current which flows in the transistor. CONSTITUTION:A fourth transformer 25 (T4) as a current detection means is connectedly inserted between the output end of a diode bridge 1 and the collector of a transistor 5, and a resistance 26 is connected between its secondary windings. The cathode of a diode 27 is connected to one end of the resistance 26 and a capacitor 28 for a high frequency bypass is connected to the anode of this diode 27 and the other end of the resistance 26, and to both the ends of the capacitor 28, a smoothing circuit made up of a resistance 29 and a capacitor 30 is connected. Then, according to a detection value of the transformer 25 which detects the current of the collector or emitter of a pair of transistors 5, 6, a charging time of the capacitor 28 is controlled. An output power becomes thereby constant without depending on a change in input voltage or a change in output load. |
