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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