| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power source device that is able to prevent heat generation and firing of a switching transistor resulting from, for example, short circuit on the load side connected to the DC output side, by further reducing the efficiency of power resulting from constant flow of current in a start resistance. ! SOLUTION: A switching power source device is designed such that a DC input voltage is supplied to the primary coil (n1) of the converter transformer (T1) by a switching operation that is on/off switched according to a voltage caused in the control coil (n3) of a converter transformer (T1), and a DC output voltage is obtained from a secondary coil (n2). The switching power source device comprises: a start resistance (R1) that causes a start current to flow in the base of a switching transistor (Q1) at the time of start, thereby starting it; connection control circuits (CN1, CN2) that connect/disconnect the DC input side and the start resistance (R1); and an unstable mu |
