pleecan Posted December 22, 2009 Author Share Posted December 22, 2009 The Garret Sidewinder is a great BFO detector but hard to come by I have had mine for over 30 years and still use it when I hunt old home sites battle fields etc. All so Jectco made a good one I think it was called Treasure Hawk. Before you buy anymore let me check around a little. Thanks Seldom... PL Link to comment Share on other sites More sharing options...
pleecan Posted December 23, 2009 Author Share Posted December 23, 2009 For those with lots of time on their hands and a bit of techincal skill.... there is a option to build your own BFO detector. ======================================================================================================================== For those whom are techy competent/ adventurous.... found a link to how to build a BFO metal detector transistor design http://www.easytreasure.co.uk/bfo.htm ================================================================================================== Another neat link with a more advance BFO metal detector design employing IC chips rather than transitors http://www.hobby-hour.com/electronics/metal_detectors.php PL Link to comment Share on other sites More sharing options...
pleecan Posted December 25, 2009 Author Share Posted December 25, 2009 (edited) more links to build your own BFO detectors... http://www.geotech1.com/cgi-bin/pages/common/index.pl?page=metdet&file=projects.dat PL Edited December 25, 2009 by pleecan Link to comment Share on other sites More sharing options...
fig rocks Posted December 25, 2009 Share Posted December 25, 2009 Looking at the options, $30 for Ebay compared to $50 + labour to build one, it seems like a no brainer? Link to comment Share on other sites More sharing options...
pleecan Posted December 25, 2009 Author Share Posted December 25, 2009 Looking at the options, $30 for Ebay compared to $50 + labour to build one, it seems like a no brainer? Good reasoning except... The trick is "If" you can find one... BFO detectors pre 1975 vintage are scarces most of the sub $50 detectors are VLF/TR design. Most modern detectors reject junk ie iron, where as this application one wants a sesitive iron detector for pyrite. In particular the BFO IC based circuitry is superior precision compared to the regular BFO transitor based detectors. PL Link to comment Share on other sites More sharing options...
32fordboy Posted December 27, 2009 Share Posted December 27, 2009 On a similar note to the topic at hand, we used a geiger counter (spelling?) on the dino dig. The difference here is that we already knew the general location where the bones were. The tool just helped us figure out the size, shape, and depth (after a little experimentation). It was really cool! Good old radiation. Nick www.nicksfossils.com Link to comment Share on other sites More sharing options...
pleecan Posted December 27, 2009 Author Share Posted December 27, 2009 That is great Nick... always interesting to bring technology from other fields to the fossil hunt... our senses is restricted to the visible relm yet instrumentation extends our senses beyond the visible relms... neat stuff. PL Link to comment Share on other sites More sharing options...
pleecan Posted December 31, 2009 Author Share Posted December 31, 2009 (edited) Jectco made a good one I think it was called Treasure Hawk. Here are the schematics for the Jectco Treasure Hawk http://www.4shared.com/file/150882635/a29e60ee/Jetco_Treasure_Hawk_BFO_from_7.html ==================================================================================================== This is a great site for metal detector docs. http://www.4shared.com/dir/22567223/bf2dbd39/Treasure_Hunting.html PL Edited December 31, 2009 by pleecan Link to comment Share on other sites More sharing options...
pleecan Posted January 9, 2010 Author Share Posted January 9, 2010 An early type Japanese BFO hand Kagakusobi-KS detector was tested... to zero out the instrument .....tuning was accomplished with a variable ferrite core adjustment on the instrument to silence the squealing detector .... pitch of the detector goes up when near metal. This is very preliminary crude test.... presented a bunch of pyritized fossils from Arkona 6mm diameter....to the detector... no shift in pitch was detetect.... no detection... suspect that the sensitivty of the instrument is low as the metal content in the fossil was sub threshold for detection of the instrument. There is another very expensive type of dectector PI = pulse inductive that may detect micro amounts of pyrite but that is too expensive prohibitive to play with for now.... PL Link to comment Share on other sites More sharing options...
pleecan Posted January 19, 2010 Author Share Posted January 19, 2010 (edited) Well folks ... continuing my monologue.... tested a BFO Treasure Hawk Jetco Metal Detector: The detector was tuned ... zero out with no metal present.... placed an iron nail and it squeal high pitch , meter defecting off scale..... now I introduce a dozen pyritized goniatites (volume equivalent of 25 cents) in a zip lock bag collected from Arkona and there was no dectectable shift in audio frequency... then slowly turned the senitivity to max.... presented the pyrited goniatites with no detectable signal. Thus so far the fossilized material contains so little iron concentration that it is below the detectable threshold... well I am going to answer this question can Metal Detectors detect minute traces of pyritized fossil material the size of a dime.... I have 2 pulse induction expensive type detectors on its way for testing.... more to come. In Summary:target= dozen pyritized goniatites (volume equivalent of 25 cents) in a ziplock bag BFO type detector.... below the detection threshold VLF type detector.... below the detection threshold PI type dectector.... pending Besides collecting fossil, I now amassed have quite a collection of different types of metal detectors for treasure hunting at the beach ... PL Edited January 19, 2010 by pleecan Link to comment Share on other sites More sharing options...
Kentuckiana Mike Posted January 19, 2010 Share Posted January 19, 2010 I am not not familiar with pulse induction detectors but I am wondering if they use induced polarization (IP) for finding minerals. After reading some of U.S. Patent 6.236,211 that refers to detecting pyrite using IP. See the patent here: http://www.freepatentsonline.com/6236211.pdf If I understand the theory correctly, the detector emits a low frequency (10-0.001 Hz) signal into a material and a receiver detects this wave some distance in that same material. An embedded computer compares the timing of the sent wave to the received wave. If a delay or phase shift is detected then something in the material was present to cause the signal to be delayed. The patent says "pyrite which has a phase-shift peak at around 0.01 Hz." An explanation of induced polarization can be found on this web page: http://www.cflhd.gov/agm/geoApplications/Quantities/813InducedPolarizationComplexResistivity.htm If that detector works, it is a clever application to find pyrite ammonites and brachiopods! Link to comment Share on other sites More sharing options...
pleecan Posted January 19, 2010 Author Share Posted January 19, 2010 Thanks for the links and information Mike!... interesting stuff to explore. PL Link to comment Share on other sites More sharing options...
pleecan Posted March 3, 2010 Author Share Posted March 3, 2010 (edited) Well folks ... continuing my monologue.... tested a BFO Treasure Hawk Jetco Metal Detector: The detector was tuned ... zero out with no metal present.... placed an iron nail and it squeal high pitch , meter defecting off scale..... now I introduce a dozen pyritized goniatites (volume equivalent of 25 cents) in a zip lock bag collected from Arkona and there was no dectectable shift in audio frequency... then slowly turned the senitivity to max.... presented the pyrited goniatites with no detectable signal. Thus so far the fossilized material contains so little iron concentration that it is below the detectable threshold... well I am going to answer this question can Metal Detectors detect minute traces of pyritized fossil material the size of a dime.... I have 2 pulse induction expensive type detectors on its way for testing.... more to come. In Summary:target= dozen pyritized goniatites (volume equivalent of 25 cents) in a ziplock bag BFO type detector.... below the detection threshold VLF type detector.... below the detection threshold PI type dectector.... pending Besides collecting fossil, I now amassed have quite a collection of different types of metal detectors for treasure hunting at the beach ... PL Well folks my testing on Metal Detectors with regards to pyrite detection. I have tested the final entry More Exotic Expensive Design...Pulse Induction type detector..... This kind of detector can detect metal in salt water ... The UniProbe Detector Pro All the electronics are built into a Head Phone complete with a probe. Detection Target is about a dozen pyritized goniatites from Arkona in a ziplock bag. The detector was zero for background.... zip lock bag with dozen pyritized goniatites was presented and .... NO Detection.... not a peep Conclusions: In Summary:target= dozen pyritized goniatites (volume equivalent of 25 cents) in a ziplock bag BFO type detector.... below the detection threshold VLF type detector.... below the detection threshold PI type dectector.... below the detection threshold What the detector will do... is to help localizes the presence of high iron deposits in the ground. This concludes testing of metal detectors for fringe applications as it pertains to locating pyritized fossils in the field. Edited March 3, 2010 by pleecan Link to comment Share on other sites More sharing options...
Western NY Explorer Posted March 4, 2010 Share Posted March 4, 2010 Hello, I have tried all of my detectors with all sorts of settings and coils to no avail. I guess we got to do it the old fashioned way. Tim the Western NY Explorer Link to comment Share on other sites More sharing options...
pleecan Posted March 4, 2010 Author Share Posted March 4, 2010 Yes indeed Tim.... At least I have a definitive answer at the end of testing... and is great to share this info with members on the forum... I have ended up with a nice Metal detector collection as the end result.... I will be bringing my pluse induction type detector to field for localization of iron pockets in shale/clay formation... we will see if we can hit a pocket of pyritized crinods/cephalopods/goniatites/trilobites..... Peter Link to comment Share on other sites More sharing options...
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