| 摘要 |
PURPOSE:To obtain a constant voltage prevented from the variation of its output voltage even if a power supply voltage is varied by starting the titled circuit by a starting circuit consisting of a diode and a transistor (Tr). CONSTITUTION:When a power supply is turned on, diodes D1, D2 are made conductive and a TrQ6 of which base is connected to an anode of the diode D1 is made conductive. Then, a TrQ3 is made conductive, Trs Q1, Q2 constituting a current mirror circuit are made conductive by the collector output current of the TrQ3 and a TrQ5 is made conductive by the base bias current of the TrQ5 to secure the base bias current of the Trs Q3, Q4. since the emitter potential of a TrQ6 is higher than the base potential of the TrQ6 in the normal operation, reverse bias is generated between the base and emitter of the TrQ6 and the TrQ6 is disconnected. At that time, its starting circuit does not operate and the output voltage is prevented from variation due to the variation of the power supply voltage. |
