| 摘要 |
PURPOSE:To prevent a piezoelectric transformer from cracking into trouble, by providing a protection circuit which stops the oscillation of an oscillation circuit when a load is short-circuited. CONSTITUTION:A current detection resistor R8 is connected in series with a high voltage rectification diode D3 coupled between the ground and the output of the piezoelectric transformer of a voltage multiplication rectifier circuit. When a load RL is short-circuited, the voltage across the resistor R8 increases and a controlled rectifier 7 is turned on. As a result, the base voltage of a driving transistor Tr2 falls, it is turned off, an oscillation circuit stops oscillating and current supply to the load RL is stopped. This state is continued until power is once cut off. |
