| 摘要 |
A power supply for high voltage, low current gas discharge tubes such as neon, argon, and mercury vapor. A free running, flyback oscillator, converts D.C. voltage energy into radio frequency energy by means of a compact, ferrite transformer and associated circuitry. The primary winding is tuned by a resonant capacitor and driven by a power transistor. A high voltage, centertapped winding of a ferrite transformer drives the gas tube load directly. A feedback winding arranged across the transistor base and emitter junction sustains oscillation and controls the drive level of the transistor by means of a regulating circuit which controls the amplitude of the current. Oscillator starting is achieved by means of an on-off switch which supplies a single starting pulse to the power transistor or by means of a time delayed starting pulse. A MOSFET transistor connected to the power transistor base and a current sensing transformer arranged in series with the primary winding, disables the power transistor momentarily at the end of a conducting cycle. Charge carries are depleted in the base-cathode region, resulting in resetting the transistor quickly such that it can withstand a forward voltage of 700 volts in the off state.
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