I posted this message on another site, and thought I would also add it here. Any comment or help would be appreciated:
I was pointed in the direction of this forum by a Mr. Bill on a treasure forum. Anyway, I was just wondering if anyone had any fairly easy to follow instruction or directions pertaining to building a monocoil for a gp series minelab detector. I have an 8"mono, 11"DD, and 18" mono which I have purchased but thought it could be an interesting project to try to build a monocoil. I was looking at building a somewhat larger one maybe around a 25" round or 32" x 18", or 34" x 16" elliptical. I did run across some information on building a monocoil at:
Page 9 gives some instruction about producing a monocoil, yet I was wondering if there is anything out there that specifically focuses on monocoils which could be downloaded or purchased. I already ran a few searches on this forum just in case and looked at the projects section as well. I know for larger coils there is some sort of problem that can be aided by a lower AWG or higher wire diameter, although the weight would suffer somewhat. Anyway, any comments or help would be greatly appreciated. (Another added note-if I manage to measure the inductance of the coils I own, how would I go about replicating the L in another coil?)
Ok, update I found a "coil calculator" but now have a different question. I came across a webpage that mentioned the need to use a oscilloscope to balance the coils. I'm just wondering what type would be best for this project and what exactly they mean by "balancing the coils". I know I should measure the inductance, capacitance, and resistance of factory coils with a LCR meter, but was wondering how one connects or measures the coil. I guess it will have to be dissected, would I connect to each end of the coil wire that comes off the coil? Anyway, any input and practical know-how would indeed be appreciated. (Again this is for building an approximately 25" monocoil for a minelab gp 3000). Note, if you know a supplier of female microphone 5-pin plugs made for thicker pins, not the thin ones often found in the U.S. that would also be useful info.
Secondly, I have bo idea what a "GP Series Minelab Detector" is, or exactially what the coil shoud be.
You mention a "Mono" Coil. In my opinion a Mono coil is a Single coil and requires No Balancing.
You also Mention a "DD" Coil, Which is Definately Not a Mono Coil. A DD Coil is comprized of Two Coils that Overlap each other. One is a Transmit Coil and the other is a Recieve Coil.
Yes DD Coils DO Require Balancing. Basically You are Required to introduce an Appropriate Signal at an appropriate Frequency into the Transmit coil, and Connect the Recieve coil to an Oscilloscope. You than adjust the positions and shapes, so that you get a Minimum Signal appearing on the Oscilloscope.
Take care..........Gary *************************************************************************** From: Rex > To: firstname.lastname@example.org Subject: Posted question the chemelec forum Date: Wed, 14 Dec 2005 22:50:26 -0700
I recently posted a couple questions on the chemelec forum and noted that you mentioned to someone there that you don't check it very often. So, I thought it might be good to send out this E-mail, as you suggested to someone else in the forum. Thanks for reviewing this message.
A little shocking that you've made metal detector coils and have never at least vaguely heard of Minelab metal detectors! I now feel obliged to give you a link, I guess Minelabs are not well known outside of those who don't practice the hobby of metal detecting for coins and gold nuggets.
If you scroll down you can click on one of the pdf. files which may be opened with adobe acrobat. I was referring to page nine. Here's a minelab info. page if you have any outside interest: www.arizonaoutback.com/minelab.html
Thank-you for the help you did volunteer. Sorry for the bad link.
Post by Gary Lecomte on Dec 16, 2005 3:32:54 GMT -8
As I Wrote in my Email to you: Yes I Definately Know about Minelabs, as a detector manufacturer.
However there are Hundreds of Manufacturers of Metal Detectors and Litterly Thousands of Different Metal Detectors on the market. I do not have the time to check them all out, nor all there specific products.
However You Specifically Asked me about a "GP Series" Minelab Detector. I Have Never seen this Particular Detector and there are NO Minelab Dealers in my area.
Besides, I am a Analogue Design Engineer, Not a Metal Detector Salesman or a Specialist in that field.
My Personal Interests include: Analogue Electronics, Woodworking, Metalworking, Inorganic Chemistry, Swimming, Camping, Kayaking and Vegetable Gardening.