Regulated high-voltage power supply with output shorting prevention

A regulated high-voltage power supply comprising

• a tuned-collector type oscillation circuit having an oscillation transistor;
• a control circuit for controlling the base current of said oscillation transistor;
• a resistance circuit for supplying the base current to said oscillation transistor in response to the output from said control circuit;
• a protection circuit having a protective transistor for receiving at least part of the output from said resistance circuit to attenuate the output from said control circuit, said resistance circuit being formed by a first resistance circuit part having high resistance value and a second resistance circuit part connected in parallel thereto and including a zener diode, said first resistance circuit part being formed by a plurality of series-connected resistor means, a first junction between said plurality of resistor means being connected to said protective transistor;
• and
• a first delay capacitor connected between said first junction and a grounded potential point for delaying the rise time of voltage at said first junction with respect to the rise time of output voltage of said control circuit,
• said regulated high-voltage power supply further including, between said first junction between said plurality of resistor means forming said first resistance circuit part and said protective transistor,
• a diode for supplying a forward current to the base of said protective transistor and
• a time-constant circuit including a second delay capacitor for delaying the time at which said protective transistor enters a non-conductive state from a conductive state, the diode preventing the storage charge in the second delay capacitor from being discharged through the first resistance circuit part, and
• discharge resistor means for discharging the storage charge of said second delay capacitor.