I have seen designs for 3 different methods. All are based on a small change in the received signal. You "calibrate" to a non-stud position & then a small change from this can be used to identify a stud. Ultrasonic - Uses the reflection phase shift I think Capacative - Uses the small difference in diaelectric constant to detect the higher density material behind the cladding. Inductive - Uses the change in Loss angle - I think - to determine the position. For metal studs, some cable locators can also be used I believe. Richard P 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 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 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.