US 3,943,417 A · Compression trimmer

Abstract

A compression trimmer for providing a range of capacitance values for an electrical circuit includes a plurality of capacitive plates spaced by one or more dielectric members and mounted on a substantially compliant, high temperature, molded plastic insulating base. The compression trimmer includes an elongated screw received within and threadedly engaging an elongated torque control hole of the compliant base. The length and diameter of the torque control hole may be ajdusted to provide a desired torque rating of the screw. Additionally, the improved interference fit between the screw and the compliant base reduces or eliminates screw vibration to thereby maintain the capacitance value of the trimmer constant. A plurality of conductive terminals extending through the compliant base are provided for connecting the trimmer in an electrical circuit, for example, by the soldering of the conductive terminals to a printed circuit board. The trimmer includes various protective features that reduce the possibility of damage or destruction of the trimmer resulting from the receipt of solder flux or solder within the base of the trimmer. These productive features include the maintenance of very close tolerances between the compliant base and the conductive terminals. Additionally, a plurality of hollowed-out portions or wells are formed in the compliant base immediately adjacent the conductive terminals for receiving and providing a cooling space for the solder flux and the solder that does enter the base 24 to thereby prevent the solder flux and the solder from damaging the capacitive plate structure of the trimmer.

Claims36

Dependent claims

A variable capacitor comprising

a first conductive capacitive plate,
a second conductive capacitive plate physically spaced from and electrically insulated from said first plate,
means for varying the spacing between said first and second plates to vary the capacitance value of said capacitor, said varying means comprising a rotatable screw having an elongated threaded shank portion,
means for physically supporting said first and second plates and for resiliently biasing said screw agains rotational movement, said supporting and biasing means comprising an insulating base formed from a compliant dielectric material, said base including means receiving said threaded shank portion, said receiving means comprising a first elongated aperture formed in said base, at least a first elongated portion of said first aperture having an inner diameter of a magnitude less than the magnitude of the outer thread diameter of said threaded shank portion prior to the receipt of said threaded shank portion to thereby enable the threaded engagement of said first elongated portion of said first aperture by said threaded shank portion and to thereby provide continuous torsional resistance to the rotational movement of said screw and to thereby prevent vibrational rotational movement of said screw during the operational life of said capacitor.

1 more element

A capacitor comprising

a first conductive capacitive plate,
a second conductive capacitive plate physically spaced from and electrically insulated from said first plate,
means for housing said first and second plates, said housing means comprising an insulating body formed from a dielectric material, said insulating body including a first, inner, generally planar surface,
a first conductive terminal for electrically connecting said first plate into an electrical circuit,
a second conductive terminal for electrically connecting said second plate into an electrical circuit,
a first elongated aperture in said insulating body through which said first terminal extends for connection to an electrical circuit,
a second elongated aperture in said insulating body through which said second terminal extends for connection to an electrical circuit,
said first elongated aperture including a lower portion having inner dimensions configured to maintain a substantially tight or contacting sealing engagement between said insulating body and said first terminal to thereby reduce or eliminate the possibility of the entry of solder flux or solder within said insulating body through said first elongated aperture as drawn by capillary action along said first terminal during a soldering operation and including first means for storing and cooling solder flux or solder that enters said insulating body through said first elongated aperture, said first means for storing and cooling comprising a first hollowed-out portion or well formed in said insulating body extending from said first planar surface to said lower portion of said first elongated aperture.

5 more elements

A compression trimmer comprising

a first conductive capacitive plate,
a second conductive capacitive plate physically spaced from and electrically insulated from said first plate,
means for applying a variable compressive force to the surfaces of said first and second plates, said compressive force applying means comprising a rotatable screw having an elongated threaded shank portion, and
means for housing said first and second plates and for resiliently biasing said screw against rotational movement, said housing and biasing means comprising an insulated body formed from a compliant dielectric material and having an elongated aperture of a fixed length through said insulating body receiving said threaded shank portion, said aperture including a first elongated portion having an inner surface of a diameter less than the outer thread diameter of said threaded shank portion prior to the receipt of said threaded shank portion to enable the threaded engagement of said insulating body by said screw and to thereby provide substantial resistance to the rotational movement of said screw.

1 more element

Dependencies are inferred from the claim text.

Compression trimmer

Life of this patent

Compression trimmer

Life of this patent

Abstract

Claims36