| 摘要 |
A contact for a rotary action variable resistor is formed of a length of wire coiled into a flattened, substantially annular spiral, with a wiper element provided by a radial protuberance on the spiral. A first embodiment has a protuberance along each of a first pair of diametrically-opposed radii. The spiral is eccentrically mounted on a substantially circular support plate, with one protuberance extending close to the peripheral edge thereof, and the other protuberance closer to the center of the plate. The spiral is attached to the plate along a second pair of diametrically-opposed radii approximately 90 degrees displaced from the first pair. The spiral is sloped so that the distance between the plate and the spiral gradually increases from the attachment radii to the protuberances. The protuberance near the edge of the plate is a resistive element wiper, and the protuberance nearer the center is the collector wiper. In a second embodiment, the spiral is mounted approximately concentrically on the plate, with a single radial protuberance. The spiral is attached to the plate along a line that defines a chord that is substantially perpendicular to the protuberance, and at least 90 degrees displaced from the therefrom. The spiral is sloped so that the distance between the plate and the spiral gradually increases from the attachment chord to the protuberance. The protuberance is the resistive element wiper, while the collector wiper function is provided by a conductive element preferably formed as part of the plate.
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