| 摘要 |
PURPOSE:To prevent a piezoelectric transformer from cracking, by providing a protection circuit which stops the oscillation of an oscillation circuit when a load is short-circuited. CONSTITUTION:When a load is short-circuited, a current flowing through a high voltage rectification diode D3 increases and the voltage across a resistor R7 rises. At that time, a PUT7 is turned on and a switching transistor 8 is turned on. As a result, the base voltage of a driving transistor 9 falls, it is turned off, an oscillation circuit stops oscillating and current supply to a the load RL is stopped. When a capacitor C1 is discharged, the driving transistor 9 resumes oscillating. Oscillation and stoppage of oscillation are thus repeated while the load RL is short-circuited. |
