12" Homemade (or so) Coil For QXT, XLT, Etc?

[Critterhunter]

Was curious if anybody had built there own larger coil for deeper coin shooting on these machines? I've tried the Hot Shot on a prior QXT Pro I owned but it would false after about ten minutes. Tried another new one with the same results. Think it might have been a bad detector because this coil should work with any of these machines. Has anybody used a Hot Shot on a QXT with no problems?

Anyway, having a background in electronics I'm interested in building a 12" or so coil for my present QXT Pro to max out my depth on coins. I'd prefer concentric for less target masking and better depth but hear a double D is easier to build, though won't go quite as deep, but will go deeper in mineralized ground than the concentric. If anybody has any links to a How-To please post it.

 

[sovereign-fan]

this site has heaps of info that mite help you out..........http://www.geotech1.com/forums/

 

[thebeatmachine]

I tried and failed. But what you do is look up ALL the patents for white's and there is the 950 coil in great detail in one of them.

 

[larrylwill]

You can build coils if you know the resistance of each winding and the inductance. On a PI machine most only use one coil so as long as you build a coil with the same resistance no matter the size it should work.
However on any other detector they are induction balanced, most manufactures pull out a couple of windings and move them around to balance the induction of the coil so any metal will upset it. I have built Double D coils and PI coils. I have also repaired induction balanced coils on many machines. The biggest problem is one winding comes loose. I used to be a repair center. There is a cheap and dirty way to re balance an induction coil from the outside using a dime.