| 摘要 |
In a switching power supply circuit in which a primary winding of a, transformer is connected to a DC voltage source through a switching transistor which is turned on and off at a predetermined frequency by voltage of auxiliary windings of the transformer, an integrating circuit is provided between the auxiliary winding of the transformer and the base of the switching transistor for making the waveform of base driving current for the switching transistor similar to the waveform of collector current in a steady state. In parallel with this integrating circuit, a differentiating circuit is provided between the auxiliary winding N3 of the transformer and the base of the switching transistor for operating only at the start of the switching power supply circuit to supply base driving current of a large magnitude to the switching transistor.
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