"The conductive material in the nail" What nail? We're dealing with wall-board (we just call it "sheet rock"!) and studs - real wooden studs! No nails! These device do indeed work on the principle of dielectric differences ... Jim ----- Original Message ----- From: "Olin Lathrop" To: Sent: Monday, February 18, 2002 5:14 PM Subject: Re: [PIC]: How does a wall "Stud Finder" work? > > Those 'antennae' don't *quite* (wincing in agonizing pain > > now as an RF-head) as actual antennas - capacitive probes: yes! > > I thought they were more inductive. The conductive material in the nail > effects the AC magnetic field near it, which causes a slight change in > apparant inductance of a coil, which causes a slight change in the frequency > of an oscillator that is sensitive to the coil inductance. > > I suppose one could conceive of systems that did use an antenna, but it > would definitely be operating in near-field, which is not the traditional > mode for what most people call an "antenna". > > > ******************************************************************** > Olin Lathrop, embedded systems consultant in Littleton Massachusetts > (978) 742-9014, olin@embedinc.com, http://www.embedinc.com > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.