| 摘要 |
PURPOSE:To accurately decide a primary-side source voltage by simple structure by adding single output winding to a power source transformer, the turning off the output of a control circuit and reading in the winding output. CONSTITUTION:The control circuit 12 rectifies the output of single secondary winding S2 by a diode 14 and a capacitor 15 and inputs it as a fine-current signal, thereby reading its output voltage VS. The voltage VS is initially 20V at the time of a light load and 18V initially at the time of a heavy load, and further the voltage is 19.8V in a light-load stable state and 17V in a heavy-load stable state. It is evident that the differences between the voltages in the initial and stable states are small and, specially, in the light load states, the voltage is 19.8V and extremely small.
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