The Basics Part 1 Coil Wire

[Infamy]

Basics a poor relation

I've spent a few weeks reading about making coils on the internet and have concluded from comments and what I have found that the basics of making coils is a mess. A disjoint series of broken links out of focus photographs and papers that fail to cover the topic of coil building to the depth necessary for a beginner to know how to avoid the pit falls. All the papers I've read on coil making fail to show the final stage and most important, testing. I recently post a thread about overlaps of dd coils and ask the question of how the gap between the coils is arrived at, well as with many other examples spread through this forum, I'm still none the wiser.

Wire

I am going to contribute one link on the basics of coilwire, if you post, add something tangible to this topic, eg types of wire, how you would graded them pro/cons, suppliers etc.

This a software I use to calculate form the metric sizes to AWG sizes. It does other things too but thats all I use it for at the moment. The software download is at the bottom of this page

http://www.wiretron.com/litz.html

That page also has some other useful info too.

[Kev]

Hi Infamy,
Coil building, that is, making a coil for your detector that is not a compromise and is better than production, or designed for a particular type of target/area, is very machine specific, that's why you will not find one size fits all, i.e. lots of disjointed and fragmentary "how to" notes.

It depends upon many things, PI is different to VLF, fast settling/early sampling coils need to be very precise, low capacitance, di-electric constant, Monos opposed to DD, Minelab PI opposed to Pulse Power, so many variables, so many solutions....many of the answers are here on Geotech, but first you must understand the concepts, and have a clear idea of what you want to achieve.

Cheers
Kev.

[Infamy]

At some point you are going to need a coil calculator, or the equations to calculate the number of turns needed for your coil. This link has two calculators and a discussion about how they work and that all important test data; "repeatability".

http://www.geotech1.com/forums/showthread.php?t=15446


Hi Kev,

I'm very disappointed, that you post and provide nothing for the thread.

I don't know if its still up but 'The humaniterrian Demining Organisaztion' made some very harsh comments on the way that detecting research has progressed and the lack of scientific rigour. It was up in their Open Source project several months ago.

With regard to variables, there are varialbes in everything, some how thoe they seem to develop a magical nature when they enter the detecting sphere.

[Qiaozhi]

At some point you are going to need a coil calculator, or the equations to calculate the number of turns needed for your coil. This link has two calculators and a discussion about how they work and that all important test data; "repeatability".

http://www.geotech1.com/forums/showthread.php?t=15446


Hi Kev,

I'm very disappointed, that you post and provide nothing for the thread.

I don't know if its still up but 'The humaniterrian Demining Organisaztion' made some very harsh comments on the way that detecting research has progressed and the lack of scientific rigour. It was up in their Open Source project several months ago.

With regard to variables, there are varialbes in everything, some how thoe they seem to develop a magical nature when they enter the detecting sphere.

You have provided a link to an old version of the Coil Calculator, which unfortunately contained a bug. I issued an updated version some time ago.
Here's the correct (latest) version:

[J_Player]

At some point you are going to need a coil calculator, or the equations to calculate the number of turns needed for your coil. This link has two calculators and a discussion about how they work and that all important test data; "repeatability".

http://www.geotech1.com/forums/showthread.php?t=15446


Hi Kev,

I'm very disappointed, that you post and provide nothing for the thread.

I don't know if its still up but 'The humaniterrian Demining Organisaztion' made some very harsh comments on the way that detecting research has progressed and the lack of scientific rigour. It was up in their Open Source project several months ago.

With regard to variables, there are varialbes in everything, some how thoe they seem to develop a magical nature when they enter the detecting sphere.

Hi Infamy,
There are many good forum posts that tell the information you are looking for, but the information is buried in the threads. There is no single definitive source that covers all aspects of coil winding. But many of the posts and articles tell the ways to wind a coil optimized for that particular project, including the approximate number of turns and wire size, as well as discussions of the trade-offs between different coil construction.

Kev is correct. There is no standard coil specification. Coils change a lot depending on what kind of a detector you want to connect it to, and what frequency it is running, as well as a lot of other things determined by the electronics. It is kind of like expecting to see a single definitive article that specifies how to wind a coil optimized for a motor, without knowing what kind of motor, how many poles, RPM, power rating, etc. There are a few good articles for building metal detector coils outside of the forums in the project areas as well, but some of these have broken links because the websites where the articles were written have been removed. Most of these articles give enough information to wind a coil for the detector, with final adjustments to be made when final tuning is done. http://www.geotech1.com/cgi-bin/page...e=projects.dat


Two particularly good coil articles can be found on the projects page:

bb Sailor PI Mono coil - (very fast for finding small gold with a PI detector)
http://www.geotech1.com/pages/metdet...s/FastCoil.pdf

Dave Emery - Coplanar search coil construction method
http://www.geotech1.com/pages/metdet/projects/coplanar/coplanar_300.pdf

To learn about the advantages of different kinds of wire and insulation as well as winding techniques, formulas and coil types, the information is all in the forum threads. It may help to use the search feature to find the exact details you want. There is also a lot of coil information in the other sections of Geotech such as the Tech forum, the Modifications forum, and the Projects forums for Hammerhead and other detector projects.

Best wishes,
J_P