| 摘要 |
PURPOSE:To reduce the power consumption of a power supply circuit by inserting a switch circuit turned on when one voltage reaches a prescribed value or below between voltage lines of different constant voltage power supply circuits. CONSTITUTION:A transistor (TR) Q3 is a switch power TR, which is controlled by a voltage comparator circuit comprising resistors R1, R2 and a constant voltage diode D1. When a voltage V1 is lowered to a prescribed value or below after the diode D1 is selected, the TR Q3 is turned on to compensate an unregulated voltage of a low voltage measurement voltage power supply circuit. A voltage V2 is compensated completely to a reduced voltage E1 through the said compensation at normal reproduction so as to stabilize the voltage V2. Since the voltage E2 can be lowered, power saving is attained. |
