| 摘要 |
In a flash device, a three-terminal switch is provided for connecting or disconnecting between a secondary coil of an oscillating transformer and a base of an oscillating transistor, between the secondary coil of the oscillating transformer and a triggering capacitor, and between the triggering capacitor and a primary coil of a triggering transformer. When the three-terminal switch is turned on, a biasing current is supplied to the base of the oscillating transistor, so a current flows through a primary coil of the oscillating transformer, and a secondary current from the secondary coil of the oscillating transformer is supplied to the main capacitor through the three-terminal switch and a base-emitter circuit of the oscillating transistor, to charge the main capacitor. The secondary current is also supplied to the triggering capacitor through the three-terminal switch, to charge the triggering capacitor. When a triggering switch is turned on while the three-terminal switch is on, the triggering capacitor discharges current through the primary coil of the triggering transformer, generating a triggering voltage for a flash discharge tube. If the three-terminal switch is turned off, the biasing current and the secondary current are cut from the oscillating transistor, and the triggering capacitor cannot discharge.
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