Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!tut.cis.ohio-state.edu!att!cbnewsc!parnass From: parnass@cbnewsc.ATT.COM (Bob Parnass, AJ9S) Newsgroups: sci.electronics Subject: Re: Metal detecting revisited - hobby that pays for itself Summary: plant a "coin garden" Message-ID: <2785@cbnewsc.ATT.COM> Date: 29 Aug 89 20:06:16 GMT References: <2575@cbnewsc.ATT.COM> <1019@electro.UUCP> <816@xroads.UUCP> Organization: AT&T Bell Laboratories Lines: 51 x I enjoyed the articles on metal detecting. Saturday, I started planting my own "coin garden." By burying a few coins at measured depths in my own yard, I can learn more about the quirks of my White's 6000 detec- tor and compare its performance to other models. Before burying any coins, I started to sweep the area for metal. Of course, the last thing one would want in a metal detector test bed is random bits of metal to dis- tract you from your targets. In the process of sweeping this small portion of my yard, I found coins and a Ster- ling Silver ring with a large (unknown type) gem! It would be a shame to dig holes, bury a few coins, then forget where they were buried. For this reason, I elected to make the burial sites visible but in a way that would not interfere with cutting the grass. I also drew a map. I cut an 8 foot long 1-1/4" diameter schedule 40 PVC pipe into several smaller pipes, each pipe 8 to 12 inches long, then buried the small pipes vertically, about 4 feet from each other. One end of each pipe is flush with the soil (not grass) surface. I buried a clad quarter at 8", a clad dime at 6", and will bury other items each in their own pipes as time permits. Each pipe is filled completely with dirt, so looking down at the ground, all that's visible is a round, white circle. In GEB/discriminate mode, the White's 6000 (with 9.5" search coil) will just barely detect the clad quarter at 8", but the identification (VDI) meter will peg at full scale, making one think the item was junk. The detector will detect the clad dime at 6", but the identification meter will not read "dime" only sometimes. In both cases, the depth meter is fairly accurate. This test convinced me to heed the advice that if a tar- get produces a "junk" meter reading, but is deep (6 inches or more), it's best to recover it. A few hours of hunting in a park Sunday netted several domestic coins, a 1943 Australian 3 Pence, a 9 mm bullet, and a few shotgun shell casings. -- ============================================================================ Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihuxz!parnass (312)979-5414