| 摘要 |
PURPOSE:To prevent a horizontal output transistor (TR) and a horizontal oscillating circuit from breaking down, by holding oscillation at a higher oscillation frequency when a higher operating voltage is detected. CONSTITUTION:The value of a limit voltage at which the TRQ of a voltage detecting circuit 11 starts turning on is determined by resistance values R1 and R2 of resistances 14 and 15 optionally. Once the TRQ turns on, the collector current of the TRQ is grounded through the resistance 16 of the base circuit of the TR17 and the base and emitter of the TR17 of an oscillation frequency switching circuit 13 to turn on the TR17, which makes a parallel connection between capacitors 19 and 20 for determining an oscillation frequency, setting the oscillation frequency of the horizontal oscillating circuit 1 to lower. When the TRQ is not turned on, the TR17 of the circuit 13 is off and the oscillation frequency of the circuit 1 depends upon only the capacitor 20, allowing the circuit 1 to oscillate at a lower frequency. |
