| 摘要 |
PURPOSE:To prevent damaging effects on characteristics of gas sensor and curtail power consumption, by eliminating DC component from AC wave forms applied to a heater of gas sensor and compensating source fluctuations. CONSTITUTION:A bridge diode 10 is installed in series in the primary winding 3 of power transformer 2 of heater 31a heating a gas sensor 31 and at the same time, a power transistor 12 is installed in the output of this bridge diode 10. This transistor 12 rectifies the output voltage of the secondary winding 4 of the transformer 2 with a bridge diode 11 and is controlled by a voltage applied through a resistance 22, a capacitor 21 and a Zener diode 17. By this construction, the voltage of the primary winding 3 of the transformer 2 is clamped at the constant voltage, and an applied voltage to the heater 31a of gas sensor 31 is held constant, and at the same time, by an action of the capacitor 21, the controlling voltage becomes formed without deformations and DC component and by a feedback action of the resistance 22, power consumption of the power transistor 12 can be curtailed. |
