| 摘要 |
PURPOSE:To easily obtain a resonance state by providing a feedback resistor for feeding back the output voltage of a switching part to the output of a phase-shifting circuit. CONSTITUTION:A quartz vibrator 1 is arranged in a gaseous atmosphere whose pressure must be measured and each of the DC voltages of positive and negative poles of constant voltage is selectively applied to the vibrator 1 from a switching part 2. Next, the output current from the vibrator 1 is converted to voltage by a current/voltage converting part 3. Subsequently, the output of the converting part 3 is shifted in its phase by a phase-shifting circuit 4 so as to minimize the impedance of the vibrator 1 and applied to the switching part 2 to subject the same to switching operation. Further, a feedback resistor 7 for feeding back the output voltage of the switching part 2 to the output of the circuit 4 is provided. When the resistance value Rr of the resistor 7 is set to 200kOMEGA, the resistance value Rd of the circuit is within a range of 6-24kOMEGA and a resonance state is obtained in this range and, further, when the resistance value Rr is set to 100kOMEGA, a resonance state can be obtained within a wide range wherein the resistance value Rd is 3.8-47kOMEGA. |
