Stud finder

A stud finder (also stud detector or stud sensor) is a handheld device used to locate framing studs located behind the final walling surface, usually drywall. While there are many different stud finders available, most fall into two main categories: magnetic stud detectors and electric stud finders. Some newer technologies exist such as RF radar with 3D imaging technology.

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 presumably attached to studs. In 1977, Robert Franklin designed a revolutionary 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 innovators developed stud finders with multiple sensor plates that sense the wall in multiple places instantly. These sensors can indicate the location, width, and lack of studs simultaneously. With more sensors, these instant stud finders avoid the shortcomings of previous electronic stud finders, which require calibration and do not adapt to inconsistencies in wall construction. While the instant stud finders have made finding studs an easy and efficient task, many people still use magnetic stud detectors.

A few stud finders use ultra-wideband scanners. They are based on the micropower impulse radar stud detector invented by Thomas McEwan.

Magnetic stud detectors use magnets to locate metal in the walling material because the magnet is attracted to the metal. The attraction grows stronger as the magnet gets closer to the metal in the walling. The strongest attraction point, if due to a metal fastener in the wall, should indicate the location of a stud, but careless wall construction can leave many metal fasteners off the studs or towards the edge, rendering the spot useless for anchoring objects. Magnetic stud detectors come in two types: stationary and moving.

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 very erratic 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 most plaster walls) the effectiveness of stationary magnets is considerably lower.

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Wikipedia