You're right!
http://www.howstuffworks.com/question271.htm
Rick

Jim wrote:

> These 'stud finders' actually find studs - they
> work on the principle that a piece of drywall
> with a stud it behind presents a much different
> dielectric constant than a piece of drywall
> without dry wood behind it.
>
> An oscillator is constructed such that at least
> some portion of both plates of a capacitor that
> comprise part of a tuned circuit are presented
> to the wall.
>
> A 'reference null' is established first on a
> piece of drywall that does not have wood
> behind it - then a search for a stud can
> commence.
>
> Jim
>
> ----- Original Message -----
> From: "Tal Bejerano - AMC" <kooter@ZAHAV.NET.IL>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Monday, February 18, 2002 2:13 PM
> Subject: Re: [OT]: How does a wall "Stud Finder" work?
>
> > wood studs in wall? maybe plastic, then no coil help :-)
> >
> >
> > -----Original Message-----
> > From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On
> > Behalf Of David Koski
> > Sent: Monday, February 18, 2002 10:06 PM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: Re: [OT]: How does a wall "Stud Finder" work?
> >
> >
> > I can see how that would work for a steel stud.  But wood?
> >
> > David
> >
> > On Mon, 18 Feb 2002 21:38:49 +0200
> > Tal Bejerano - AMC <kooter@ZAHAV.NET.IL> wrote:
> >
> > > yeah coil and  a very sensitive circuit..
> > > this is the right and the only way
> > >
> > > Tal
> > >
> > > -----Original Message-----
> > >
> > > Anyone out there know how a wall "Stud Finder" works? I imagine a coil
> > > with some sort of level detection but I am curious.
> > >
> > > Cheers,
> > >
> > > Kevin
> >
>
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