A vacuum variable capacitor includes a vacuum sealed enclosure to contain a vacuum dielectric medium, wherein the enclosure includes a first plate and a second plate, the first plate and the second plate being separated by an electrically insulating element, a fixed electrode attached inside the enclosure to the first plate and a movable electrode attached to a movable plate, wherein the movable plate is attached inside the enclosure to the second plate by at least one vacuum bellows, wherein the vacuum capacitor includes a mechanical drive system for displacing, in particular translating, the movable plate relative to the first plate so as to vary the capacitance of the vacuum capacitor, wherein the mechanical drive system includes a ball screw arranged to drive the movable plate and wherein the mechanical drive system includes outside of the vacuum sealed enclosure a limiting element limiting the maximum distance between the first plate and the movable plate and wherein the drive system includes a nut attached to the ball screw, wherein the nut includes a first shoulder configured to abut against the limiting element to limit the maximum distance between the first plate and the movable plate.

A vacuum variable capacitor includes a vacuum sealed enclosure to contain a vacuum dielectric medium, wherein the enclosure includes a first plate and a second plate, the first plate and the second plate being separated by an electrically insulating element, a fixed electrode attached inside the enclosure to the first plate and a movable electrode attached to a movable plate, wherein the movable plate is attached inside the enclosure to the second plate by at least one vacuum bellows, wherein the vacuum capacitor includes a mechanical drive system for displacing, in particular translating, the movable plate relative to the first plate so as to vary the capacitance of the vacuum capacitor, wherein the mechanical drive system includes a ball screw arranged to drive the movable plate and wherein the mechanical drive system includes outside of the vacuum sealed enclosure a limiting element limiting the maximum distance between the first plate and the movable plate and wherein the drive system includes a nut attached to the ball screw, wherein the nut includes a first shoulder configured to abut against the limiting element to limit the maximum distance between the first plate and the movable plate.

The present application discloses a center-perforated annular ceramic capacitor. An annular capacitor is formed by combining and sintering a ceramic base and a ceramic reaction diaphragm, and axes of the ceramic base and the ceramic reaction diaphragm are both provided with through holes to provide an assembly path for circuit elements to be combined, and a structure of the temperature-pressure sensor as a whole is simplified, including a circuit and a sealing structure, thereby enabling the temperature-pressure sensor to have a structure of automatic assembly and reducing the production and assembly costs; the first annular circuit and the second annular circuit of the annular capacitor design have a higher initial value and wider capacitance variation compared with the central non-through hole disc-shaped ceramic capacitor, so that the annular capacitor has a wider measuring range and finer pressure sensing classification, thereby improving accuracy of pressure measurement.