How to change the depth of a large object.

[sanmao998]

HI. Guys, I built a pulse detector. Coil size 20 inches. Testing 5-inch objects can detect up to a depth of 30 inches. But testing larger objects doesn't have great depth. The 15-inch test object is only 50 inches. What would need to change to increase the depth of a large object?

[Carl-NC]

Too many variables for a simple answer. What are you wanting to detect (material, physical size, and time constant) and how deep?

[Sean_Goddard]

More TX power, more front end gain. Less system noise....The list goes on.

[sanmao998]

Too many variables for a simple answer. What are you wanting to detect (material, physical size, and time constant) and how deep?

A large number of copper coins were mainly deposited, as well as a large number of silver coins

[Carl-NC]

A large number of coins do not behave like a single large target, they behave like a lot of small targets making them more difficult to detect. Make yourself a replica of what you are looking for using modern coins or whatever. This will give you more realistic test results.

You also have not described what kind of PI you built, nor it's operating parameters. But most PIs are not built for cache hunting so they are not optimized for high conductors. You might try increasing the TX pulse width to 300us or so, which likely means decreasing the pulse rate so it doesn't burn up. Then look at the sample width and integrator tau. Lots of things to consider.

[bbsailor]

HI. Guys, I built a pulse detector. Coil size 20 inches. Testing 5-inch objects can detect up to a depth of 30 inches. But testing larger objects doesn't have great depth. The 15-inch test object is only 50 inches. What would need to change to increase the depth of a large object?

As Carl stated, there are too many variables for a simple answer to your question. However, given your stated desire to detect a 15 inch object at deeper than 50 inches using a 20 inch coil, I would try using a larger diameter coil such as a 30 to 40 inch diameter coil. You may want to check the coil wire diameter to ensure that the current stays strong enough to reach the target on a test. You also may want to lower the TX frequency to ensure the proper amount of current is stimulating the target at your desired distance. As you can see, many variables are involved so take good measurements of your new coil performance and post your results if you need more help. Are you taking one sample or are you integrating multiple samples? Desired performance is balancing the variable tradeoffs and keeping a good record of your test data.

Joseph J. Rogowski

[EL NINO]

Currently made detectors with 11 "coils are capable of reaching a depth of 125 cm for objects such as a military helmet...or for a silver coin in the size of a silver tolar or a dollar at a depth of 40-45 cm..
if you have a problem getting a signal on a 15" /37.5cm/ large target.. at a depth of 125cm, the problem will probably be that this target is very highly conductive and that is why some detectors have a problem seeing such a target not only in the ground but also, for example, during a test air test ... or they can see such a target but have reduced sensitivity and range... because they are not well calibrated for this type of target..

I myself use for control testing a Russian military aluminum field bottle from WW2.. which is one of such difficult targets../Russian imperial aluminium field bottle from WW1 is an even more difficult target/..

[sanmao998]

Thank you for your replies. I don't understand electronic circuits. I'm just a treasure hunter and the motherboard I'm using is supposed to be a plagiarized Gold Mask 2. Don't know how to describe the running parameters.

[Tanu]

Currently made detectors with 11 "coils are capable of reaching a depth of 125 cm for objects such as a military helmet...or for a silver coin in the size of a silver tolar or a dollar at a depth of 40-45 cm..
if you have a problem getting a signal on a 15" /37.5cm/ large target.. at a depth of 125cm, the problem will probably be that this target is very highly conductive and that is why some detectors have a problem seeing such a target not only in the ground but also, for example, during a test air test ... or they can see such a target but have reduced sensitivity and range... because they are not well calibrated for this type of target..

I myself use for control testing a Russian military aluminum field bottle from WW2.. which is one of such difficult targets../Russian imperial aluminium field bottle from WW1 is an even more difficult target/..

Hello
i have question
you mean high conductive target difficult to detect metal detector?

I through before Highly conductive target have great depth compare Low conductive target.

[Carl-NC]

PI detectors are mostly designed for the beach or gold fields and are optimized for small low and medium conductive targets. They are less sensitive to high conductors. VLF tend to be most sensitive to high conductors.

[Tanu]

PI detectors are mostly designed for the beach or gold fields and are optimized for small low and medium conductive targets. They are less sensitive to high conductors. VLF tend to be most sensitive to high conductors.

Thank you carl
I want detect brass pot and fill some coin.pot diameter more than 6 inches normal to medium soil(some time soil have iron)
How deep can I go

[kt315]

Carl means NOT Ohm conductivity. you must NOT be misleaded. we say about Fuko' current, Eddy current, the vortex-current.

[Tanu]

Oh thanks
pi detectors less sensitive to brass,copper,gold ?