coils

[rick]

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..

[Joe Rutsky]

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

[rick]

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

[Carl]

>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

[rick]

>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...

[rick]

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---