History
Stud finders have been in use since the early 20th century, and the first ones were all magnetic, relying on internal magnets to detect the walling fasteners or nails presumably attached to studs. In 1977, Robert Franklin designed an electronic stud finder that relied on an internal capacitor to measure changes in density behind the walling. His patent was put into production by the Zircon Corporation, which became the sole producer of electronic stud finders until the patent expired in 1998. While novel, these electronic stud finders did not always prove effective in locating studs. Since 1998, many developments and improvements have been made to the internal capacitor stud finders and increased their popularity. Recent developments include stud finders with multiple sensor plates that sense the wall in multiple places. These sensors can indicate the location, width, and lack of studs simultaneously. With more sensors, these stud finders do not require calibration and adapt better to inconsistencies in wall construction. A few stud finders useMagnetic stud detectors
Magnetic stud detectors useStationary magnetic detectors
Stationary magnet stud detectors use a small stationary magnet to detect the nails or screws placed into studs while putting up the walling material. The user must move the magnet around the wall until feeling the pull of magnetic attraction, and move in the direction of attraction. Since stationary magnetic stud detectors rely on the user to feel the attraction they can be unreliable, especially when the metal fasteners are located more deeply in the walling, which decreases the overall attraction. When fasteners are deep or buried under thicker walling material (as in mostMoving magnetic detectors
Moving magnet stud detectors use aElectronic stud finders
Electronic stud finders rely on sensors that detect changes in theEdge finders
Edge finders are the most basic internal capacitor detectors. Edge finders detect the edges of the stud or other material behind the walling. This finder must first be calibrated over an empty section of the wall, and then it can be moved along the wall until it senses a change in density - such as the edge of a stud. Edge finders should be moved from both directions to find both edges of the stud. The single sensor in edge finders can be prone to error, sometimes indicating a spot an inch or more from the stud’s edge. Once both edges have been marked, the user must determine the location of the stud’s center.Center finders
Center stud finders detect the center of the stud by using two sensors that register separate readings of the wall’s dielectric constant. When the two readings match, the finder indicates that it is centered on a stud. The several readings are used to determine the target center. Center finders only need to be moved from one direction. Like edge finders, center finders require calibration. Wall texturing can cause bumpy movement across the wall impairing the calibration readings.Instant stud finders
Instant stud finders are a more recent development. Instant stud finders have multiple sensor plates, and do not need to be moved across the wall to detect a stud, overcoming the effects of bumpy wall texture. They use an algorithm to analyze the readings from the multiple sensor plates for a quicker, more accurate indication. Instant stud finders sense multiple regions of a wall simultaneously including the center of a stud, edges of the stud, and regions without studs. Instant stud finders will indicate varied widths of studs and the location of multiple studs at the same time. Because the instant stud finders use multiple readings to determine the location of studs they are also less vulnerable to construction anomalies (such as uneven paint, wall textures, wallpaper, uneven plaster, etc.) that can disorient center and edge finders.Radar scanners
The newest stud finders in the industry implement radar technology. Using raw signals transmitted by their sensors, they are able to classify different wall types as well as the material behind the walls. This allows for detection of studs, pipes, wires, leaks and even motion such as pests or rodents. One of their advantages is the ability to work on older houses, such as ones with lath & plaster wall types.References
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