Stud finder

A stud finder (also stud detector or stud sensor) is a handheld device used to determine the location of framing studs used in light-frame construction after the walling surface has been installed.

There are three main types of these devices:
* The first uses a small magnet to detect the nails or screws placed into studs during the manufacturing of the wall.
* The second type uses an internal capacitor plate to detect changes in the dielectric constant of the wall as the user moves the finder over the surface of the wall. A significant change in the dielectric constant indicates the presence of a framing stud.
* The third type uses a very small radar system to show exactly where the edges of a stud are behind the wallboard (drywall).

There are two methods used to find the stud in the wall:
* The first kind detects the edges of the stud. The sensor has to be moved from both right and left directions and the edges should be marked.
* The second kind detects the center of the stud. The sensor needs to be moved from one direction and it will indicate the center of the stud. This kind of sensors are also called One-Step finders.

See also

* [http://home.howstuffworks.com/question271.htm "How do stud finders work?"] at HowStuffWorks.
* [http://patft1.uspto.gov/netacgi/nph-Parser?patentnumber=4099118 "Electronic wall stud sensor"] at USPTO