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  • coils

    glad to find another forum for more technical folks.


    would like to know anyones position on coil geometry


    for pi,vlf,bfo,etc.


    looking at patents (whites bluemax) and a few others


    as well as some experimenting here ----well simply


    put---still hungry----


    have found no patent for elliptical,"big foot"


    "hot coil" etc.


    yea---smaller coil- smaller target less depth


    larger coil-bigger target more depth


    why is the elliptical supposedly less suseptible


    to ground mineral---???? less area laterally ???


    as opposed to the conical shape field from concentric


    coil----hence less imbalance


    why elliptical for gold---


    think some of words in market place is hype


    etc..

  • #2
    Re: coils

    I know what you mean about being hungry for information. I study all I can about detectors and just can't get enough!!


    I don't know much about the design of coils for VLF machines but Eric Foster put up a nice post about the rectangular coils for PI. Supposedly a 3 to 1 ratio rectangular coil increased depth a little. Haven't done much with it yet.


    Either way you look at it, the depth of the signal you get out of the coils - i believe - can be figures using an inverse sqaure ratio formula. So the amount of power needed to increase depth is considerable. Being that VLF machine - I think - are limited to 100 mW output, I really don't think that any considerable depth would be gained by any specific coil on the market. They just have to be properly tuned to the circuit.


    And - yes - like any advertising dealing with retail, you have to watch those buzz words that really mean nothing.


    By the way - go to the resources section of this page, and try going to the detectknowledgy web site. A lot of good info there, too.


    Joe

    Comment


    • #3
      Re: coils

      thanks for input joe--


      yes found erics site before this one, as well as


      some others---ibm patents also nice--but time


      consuming--however much there....most of which


      is copied here on a immation disk 120mb floppy...


      me go there, glance, if interesting copy and consume/


      digest later at my lesure, and have for reference


      later if can keep track of it all.


      many factors to consider--was doing the start on vlf


      (experiment bench) then found pi (erics mainly)


      and yes discriminate with vlf---but question


      reliability of such---target distance from coil


      if not close ~5"or so on a 7" coil can not be trusted


      also target orientation if even close---a copper


      coin can look as ferrous etc..quite dramatic


      a numbers game---on avg the coin will be parrallel


      to coil at a nominal distance etc....


      dont like shaky ground---maybe a pi is better if only


      could tell ferrous/nonferrous at minumim.


      dont think vlf is all that made out to be---not saying it does not work at all--someone erics site said the correct tool---me make all 3 vlf,pi,and bfo........you say

      Comment


      • #4
        Re: coils

        >glad to find another forum for more technical folks.


        >would like to know anyones position on coil geometry for pi,vlf,bfo,etc.


        >looking at patents (whites bluemax) and a few others as well as some experimenting here ----well simply put---still hungry----


        >have found no patent for elliptical,"big foot" "hot coil" etc.


        >yea---smaller coil- smaller target less depth larger coil-bigger target more depth


        >why is the elliptical supposedly less suseptible to ground mineral---???? less area laterally ???


        >as opposed to the conical shape field from concentric coil----hence less imbalance


        >why elliptical for gold---


        >think some of words in market place is hype


        > etc..


        Glad you dropped by, Rick. Yes, I've read that some these aftermarket coils are all hype. I don't have any experience in coil geometry so I can't answer your questions. I think it will probably have to be learned through bench experimentation. Hopefully, one day, this info can be assembled and written up. In the mean time, let me know what patents and other sources you are looking at and I will add them to the Resources page.


        - Carl

        Comment


        • #5
          Re: coils

          >Glad you dropped by, Rick. Yes, I've read that some these aftermarket coils are all hype. I don't have any experience in coil geometry so I can't answer your questions. I think it will probably have to be learned through bench experimentation. Hopefully, one day, this info can be assembled and written up. In the mean time, let me know what patents and other sources you are looking at and I will add them to the Resources page.


          >- Carl


          there are a bunch---bfo,vlf,pi a nice selection


          perhaps 30 or so---have them stored (content)on


          a 120mb floppy (immation super disk)


          do not want to make ibm or patent office mad---


          they take web site down ?????


          me make list like 4030026,5414411,5576624 etc..


          think it illeagal for me to send content over net


          to anybody ??????not sure----would be nice if not


          could save all lots time to download themselves


          me hate this legalized 100000000000 law etc...

          Comment


          • #6
            Re: coils

            oops---just blasted the patent list--only it was to erics site----they probably wont mind---do you want


            me to retype list for you----seems eric wrote here


            a couple of times----me new at computer----


            patents


            Thursday, 06-May-99 13:12:27


            209.181.67.214 writes:


            here you go----all 60---there are still others


            some are a little out of it---like 3 big coils


            on front of airplane---but you can learn something-----


            3823365,3826973,3835371,3848182,3872380,3896371


            3961238,3986104,4024468,4030026,4053828,4099116


            4110679,4128803,4130792,4213093,4249128,4249129


            4255711,4263553,4283680,4300097,4303879,4321539


            4344034,4345208,4423377,4470015,4486713,4563645


            4659989,4677384,4700139,4709213,4719421,4783630


            4862316,4868504,4868910,4926127,5130655,5414411


            5506506,5523690,5576624,5691640,4881036,4894619


            4942360,5537041,5729143,3882374,4293816,4595877


            4890064,5557206,4096432,4325027,4434192,4514672


            these are after 1974 as the data base does not have any patent later than this on line---too


            bad


            somtimes the older stuff is better-----


            http://www.patents.ibm.com/patquery


            oh that is how to do----me just learn-open new window


            copy/paste-----do not laugh too hard---

            Comment

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