| 摘要 |
PURPOSE:To stabilize an output voltage value by detecting the voltage value of a control winding provided at the primary side of a high frequency transformer, and controlling the drive time of a drive winding in response to the output voltage of the winding. CONSTITUTION:The collector voltage of a switching transistor Q2 linearly increases from zero, and when it arrives at the prescribed point, the transistor Q2 is saturated, a bias power source necessary to drive the current more than the saturation is eliminated to turn the transistor Q2 OFF. A control winding N3 is provided at the primary side of a transistor T2, and the variation in the input voltage is detected by the control winding NB. When the input voltage increases, the base voltage of a transistor Q4 is raised from the reference voltage value of a constant-voltage diode D2. Thus, the transistor Q4 is operated, the base current of the transistor Q2 is controlled by the transistor Q3 to control its drive time. |
