PURPOSE: To obtain a stable frequency over broad temperature range by making frequency corrections of a tertiary curve in a range of 0∼50°C and at a low-temperature side, where it is nearly straight, by use of a capacitor.

CONSTITUTION: The base of bimetal 1 is fixed on fixation foundation 3 by screws 2 and near the base, adjusting screw 4 is screwed in so that its tip comes into contact with top surface of fixation foundation 3. Then, fixation foundation 3 is equipped with electrode 5 and on its top surface, dielectric 6 is mounted. The top surface of dielectric 6 and the reverse surface of bimetal 1 should be at a slight interval. This fine interval is adjustable by adjusting screw 4. Namely, one electrodes employs bimetal 1; and below a certain temperature, the interval between the electrodes is widened to reduce the capacity valve and above the temperature, the interval between the electrodes is kept constant to maintain the constant capacity.