| 摘要 |
PURPOSE:To improve the voltage variation rate of an output DC voltage by connecting a Zener element in series with a photoreceptor optically coupled with a light emitting element driven by the output of comparing means. CONSTITUTION:An AC power source AC is rectified by a rectifier REC1 to a DC voltage, applied through the primary winding W1 of a transformer TR to an oscillation transistor (Tr) Q1, which is driven by a current of a feedback winding W3 of the transformer TR to obtain output voltages from three secondary windings W21-W23. In this case, the output of a rectifier REC2 of the secondary winding W21 is produced as a control voltage V1 to drive a light emitting element PD in response to the output of a comparator OP. Further a photoreceptor PT optically coupled with the element PD and a Zener element connected with the base of the TRQ1 are provided. Thus, the current amount of the element PT is varied by the element PD driven in response to the output voltage, the forward bias of the Zener element D3 is varied to alter the ON time of the TRQ1. |
