| 摘要 |
PURPOSE:To reduce the power consumption of a switching power source by controlling the switching element of the primary winding of a transformer through an optical coupling element by an external signal. CONSTITUTION:An AC input 1 is rectified and smoothed by a diode bridge 4 and a capacitor 5, and intermittently connected through the primary winding of a converter transformer 30 by switching transistors (Tr) 6, 7 to generate an induced voltage at the secondary winding of the transformer 30, thereby outputting a plurality of desired voltages. In this case, a phototransistor (photocoupler) F is added between the base of a control Tr 14 and the base of the Tr 7. The oscillations of the Trs 6, 7 is stopped by an external signal when the output is no-loaded, thereby preventing the wasteful loss of a power source from occurring.
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