Stud finders as you know are little devices used to located the beam of wood running through a drywall, so you can find something strong to screw things to.
They are normally handheld devices, which are used to sense where the material behind the device is more dense.
The wooden beam is of course denser than the weak plasterboard, and this is what stud finders pick up. they often emit a beeping noise, or an LED will flash when they sense a stud is behind the device. This alerts you to the location of the beam so you can make a note with a pencil or a knife and start using the stud.
To the right you can see a picture of a plaster board wall, with the wooden studs exposed. These are what the stud finders are detecting, as you can see in this picture, the white marks going along the studs on the right hand side are screws.
They have been placed there because that’s the strongest part of the wall, the wooden beams running either top to bottom, or sideways as shown here.
Using ‘Changes In Density’ To Find The Stud..
How do stud finders work? Well, it’s actually fairly simple. Materials like wood are very poor electrical conductors, they are in fact ‘insulators’ meaning they don’t conduct electricity at all. What they are good at, is supporting what’s called an ‘Electrostatic field’.
This is a type of electrical/static energy which the stud finder detects with a ‘Capacitor plate’. This detects changes in an electrostatic field, in this instance, the difference in density between plasterboard and a thicker and more dense wood (The stud).
This and a clever circuit board in the scanner allow it to detect with some accuracy where the edge of the stud is, it’s where to density suddenly changes.
More Advanced Stud Finders..’Multi Scanners’
Some electronic stud finders can even detect the type of material based on how dense it is, and using a combination of different scanning techniques some of the more expensive stud finders can detect hidden metal pipes, electrical wires and screws/nails etc. Some can even scan up to 3-4 inches deep.
These more advanced types of stud finder are called ‘multi scanners’ or multi purpose stud finders. They can be used for more than just finding studs on drywalls, for example finding the beams in the ceiling, floor, locating metal behind walls or other surfaces, even locating metal/screws behind tiles.
They use a combination of small scale radar, metal detecting hardware, density sensors and magnets.
A combination of these scanning methods allow the more advanced models to give an accurate image of what’s behind and embedded within a wall.