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Pulse Induction Coil Data

The document provides detailed instructions for constructing pulse induction coils for metal detection, including specifications for single and dual coil designs. It emphasizes the importance of coil winding, capacitance, and finishing techniques to enhance performance. Additionally, it discusses the advantages of using dual coils for noise rejection and the benefits of different wire gauges for optimal magnetic fields.

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100 views3 pages

Pulse Induction Coil Data

The document provides detailed instructions for constructing pulse induction coils for metal detection, including specifications for single and dual coil designs. It emphasizes the importance of coil winding, capacitance, and finishing techniques to enhance performance. Additionally, it discusses the advantages of using dual coils for noise rejection and the benefits of different wire gauges for optimal magnetic fields.

Uploaded by

rinunes
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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http://www3.telus.net/chemelec/Projects/Metal/Metal­C.

htm Go JUL SET DEZ

50 captures 9
5 Ago 03 ­ 24 Ago 12 2006 2007 2008

Pulse Induction Coil Data


Single Coil
Revised 10/16/2006

Winding: Coil is aproximately 40 turns, No. 28 Awg. Either wound in a round


shape, square or in a rectangle! A Diameter of about 6 to 8 inches is about
normal. In a Rectangle, Optimum is about a 4 to 1 ratio, length to width.

Some guys using my detector have wound coils up to 4 Feet Square for deep
searches of large objects! These large coils are usually only 4 turns or so!

Each has its advantages and disadvantages! Also more turns and bigger wire
equils a greater magnetic field. But don't go overboard.
Even very small coils of a "1 inch" diameter can be useful!

Low Capacitance is important in the coils. This can be further acomplished


by winding the coil in a single layer spiral. It's not too easy to do,
but it can be done and will make your unit much better.

Here are some test that I have done on wires in the 22AWG to 18AWG range:

1) Two parallel wires, close together, 1 foot long 18AWG = 42 Pf.

2) Two parallel wires, close together, 1 foot long 20AWG = 39 Pf.

3) Two parallel wires, close together, 1 foot long 22AWG = 36 Pf.

These tests were done at a frequency of 1000 Hz.

This Only affects Direct Parallel Wires, But does not Coils in the same manner.

However, Capacitance can greatly reduce the effectiveness of the coil!

Finishing: After you are happy with the coil, it is important to lay the
coil on a solid piece of NON‐METALIC material and EPOXY it so it is RIGID.
As small amounts of movement within the coil can affect performance a bit!

Also make sure the Wire leads coming from the coil, go out horizontal,
Not directly Above or below the coil!

Dual Coil, Cancelling Design

Two coils have the advantage of "Noise Rejection" should their be unwanted
interferance in the vacinity of your search! One coil does the search,
While the other coil cancels noise and simular signals.
Particularly useful if it is to be used near Power Lines or soil
containing a lot of iron deposits!

If two coils are used, they are easiest done round. Wind both identical
and overlap them up to about 50%, but not greater than. Keep both wound
in same direction when overlapped! The Less the overlap or no overlap,
will results in a smaller confined field of search, covering less area.

Follow the Winding and Finishing Instructions for the Single Coil as well
as the info here that is related specificially to the Two Coils!

Dual Coils, Seperate Recieve & Transmit

This Coil Configuration allows the transmit coil to be constructed for


maximum magnetic field with a fairly heavy wire, while using a recieve
coil with more turns of smaller wire for better pickup.

Picture Of one of the Coils I made.

All Imformation in this Article is "Copyright protected".

Chemelec

*Copyright © 2003 & 2006*

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