Building Concentric Coplaner coils

This document is intended to demonstrate one method of constructing Concentric Coplaner coils. While it is targeted toward the home hobby builder it is not as simple as the more popular DD coil configuration.

The Concentric coil configuration does however offer some advantages over the DD coil. Some of these advantages include cost of construction, lighter weight, easier pinpointing, greater detection distance for a given diameter, better discrimination and iron rejection.

Even though constructing the Concentric coil can be a little tricky, it will be demonstrated that it can be done successfully! In this example we will be building a coil to match a Tesoro coil for the popular TGS project. While the specifications for a Tesoro coil are presented here, similar construction methods can be used for a multitude of coils.

To begin with, let us take look at our desired specifications for a TGS coil:

Wire size: .25mm (30 AWG) enameled

Tx inductance: 6.0mH

Tx resistance: 18 – 25 Ohms

Tx resonance - About 14.5 kHz

Rx Inductance: 6.5mH

Rx resistance 18 – 25 Ohms

Rx resonance with 15nF – About 16.1 kHz

Canal do autor: https://www.youtube.com/watch?v=ie830PIqfxk