Silverdog PI 1.2 kit Ground balancing

[xlev]

Hi guys

I am just wondering if the Silverdog Surfmaster PI kit comes with Ground balancing capabilities? I saw someone building it here in Australia, and he said that when it
took it to the minefield, it was useless because of the mineralization and the lack of ground balancing. So I assume that it doesn't come with ground balancing?
If so, is it possible to add ground balancing to it?
Also, I couldn't find anywhere any real data about the capabilities of the Surfmaster PI 1.2 kit, I have seen numerous air test, but they don't mean much. Has anyone
done actual test in the ground? And does anyone look for gold with it?

Thanks guys for all your help

Regards

Alex

[6666]

I am just wondering if the Silverdog Surfmaster PI kit comes with Ground balancing capabilities?

No

[xlev]

Thanks for the answer.

I found this post, which explain how to add ground balancing to a VLF metal detector http://www.findmall.com/read.php?17,811185,812782
Do you think you could to the same to a PI detector? Has anyone tried?

Otherwise, does anyone know of any other PI kit which would have ground balancing?

[kt315]

Otherwise, does anyone know of any other PI kit which would have ground balancing?

HAMMERHEAD-PI of Carl Moreland (ufff... you are on his site now). it has a secondary sample delay being tuning. enough for the ground balancing.

[mickstv]

HAMMERHEAD-PI of Carl Moreland (ufff... you are on his site now). it has a secondary sample delay being tuning. enough for the ground balancing.

The Hammerhead doesn't ground balance, it just has a secondary sample like the SurfPI, which is used to cancel out the Earths magnetic field.

[Qiaozhi]

Thanks for the answer.

I found this post, which explain how to add ground balancing to a VLF metal detector http://www.findmall.com/read.php?17,811185,812782
Do you think you could to the same to a PI detector? Has anyone tried?

Otherwise, does anyone know of any other PI kit which would have ground balancing?

The Surf PI does not have a ground balancing capability. The link you gave is for a Tesoro Cibola, which a VLF machine that already has an internal ground balance circuit. The modification discussed is simply moving the internal control to the front panel.
Adding ground balance to a pulse induction detector is more complicated. See page 174 of "Inside the METAL DETECTOR" for more details.

[kt315]

The Hammerhead doesn't ground balance, it just has a secondary sample like the SurfPI, which is used to cancel out the Earths magnetic field.

HH, Delta Pulse, Deepers 10DD and many another do ground balance. EASY. because you TUNE them on the GROUND. PI method itself cancels any field and any ground. surf and barracuda have NOT secondary samling operative tuning, its fixing on some value and attached to first samling, NO operative tuning you could encrease a depth in those machines.

[kt315]

How Metal Detectors Work


By Mark Rowan & William Lahr


Ground Balance Ground balancing, while very critical on VLF metal detectors, is not necessary with PI circuits. Average ground mineralization will not store any appreciable amount of energy from the search coil and will not usually produce a signal. Such ground will not mask the signal from a buried object. On the contrary, ground mineralization will add slightly to the duration of the reflected pulse increasing the depth of detection. The term "automatic ground balance" is often applied to PI instruments because it will normally not react to mineralization and there are no external adjustments for any specific ground conditions.
Heavy black sand is an exception. It will cause a VLF coil to overload, making metal detector penetration poor at best. A PI detector will work in black sand however, some false signals may result if the coil is held very close to the ground. Ground responses can be minimized by using a longer time delay between the shut-off and sample point (pulse delay). Advancing the time delay slightly will help to smooth out the noises caused by most mineralization.

PI Summary Pulse Induction metal detectors are specialized instruments. They are generally not suitable for coin hunting urban areas because they do not have the ability to identify or reject ferrous (iron) trash. They can be used for relic hunting in rural areas where iron trash is not present in large quantities, or is desired. They are intended for maximum depth under extreme search conditions such as salt water beaches and highly mineralized ground. In such conditions PI type metal detectors produce superior results when compared to VLF models, particularly in the ability to ignore such extreme ground and penetrate it for maximum depth.

[Mechanic]

Perhaps if you intended to use a pi detector in non gold bearing areas, ground balance might not be so important. Here in Australia, the ground is bad and a pi detector will not "just ignore" the mineralization. Ground balance is required to subtract out the ground response, leaving the target response intact. A pi that only has 2 samples will not be able to ground balance. There would need to be at least a 3rd sample and a way to adjust something to account for the varying conditions.

Cheers Mick

[kt315]

Mick, I would be glad to tell you about QED and give you a link. but.... greedlab is hunting on what you only told about and on progressive people. no one best PI will not come to light you would be repeat of. greedlab will not give you even a tiny chance. yes, simple PI and 2 sampling. this is yet not in restricted area of greedlab. you have to write this, not me. you are there in Australia, not me. if you have something new on QED e-mail me pls the files. tia. (hey Mick, are you NOT the chief engineer of greedlab there?...)

[Bill512]

there is even today a big misconception about Pulse detectors and ground signals.
My opinion: this is another popular American myth from the '80's.
In most circumstances a pulse machine it will give ground signals.
Anyway, at any case, the metal signal to ground signal ratio will be low.
Now about Surf Pi, you can try to add ground balance using the second sample.
the trade-off? you lose 20-40% of the normal "depth".
Of Course, also you lose the benefits of the normal use of the second sample, but my goal was to learn about Ground Balance.
As Mick said, finally you must use 3 samples (minelab) or 4 (TDI).

[kt315]

finally you must use 3 samples (minelab) or 4 (TDI).

I vote for 512...1024 samples, its imaging on LCD colour screen and automatic ground balance. so who will do this non-patented by ML machine? aooo, Aziz?! where are you there??

[Waikiki_Sweep]

Is it possible to ground balance salt water somehow? I have Surf PI but that noise from every sand bump on the ocean bottom makes me sick. Also if I stay in water and rise coil up from the bottom to few inches it makes beep every time. I think it is ground balance problem.

[Mechanic]

[QUOTE=kt315;179422]Mick, I would be glad to tell you about QED and give you a link. but.... greedlab is hunting on what you only told about and on progressive people. no one best PI will not come to light you would be repeat of. greedlab will not give you even a tiny chance. yes, simple PI and 2 sampling. this is yet not in restricted area of greedlab. you have to write this, not me. you are there in Australia, not me. if you have something new on QED e-mail me pls the files. tia. (hey Mick, are you NOT the chief engineer of greedlab there?...)[/QUOTE]

LOL, far from it!!! They have not paid me yet!!! Though they did like my pinpointer modification enough to design one around the principle.

The reason I said that there would need to be at least 3 samples is because thats just the way it is. It could be done with 2 samples, however the static magnetic field cancellation would not work thus making the detector run like garbage. The other alternative is to use a bipolar tx pulse, then 2 samples could be effectively used, however I don't know if there are patents on this. More than 3 samples would also work. With a 2 sample version, if the 2 samples were very close together, the ground response would be minimized and the detector would be very sensitive to smaller targets. Depth would be reduced on large targets significantly.

As far as I know the QED development has stopped and I don't have anything new on it.

I do believe that the patents covering the sd2000 have expired....

Cheers Mick

[mickstv]

HH, Delta Pulse, Deepers 10DD and many another do ground balance. EASY. because you TUNE them on the GROUND. PI method itself cancels any field and any ground. surf and barracuda have NOT secondary samling operative tuning, its fixing on some value and attached to first samling, NO operative tuning you could encrease a depth in those machines.

HH will not Ground Balance in heavily mineralized areas like i.e. Australia's gold fields. Its impossible without major modifications and adding at least one or two more samples.



Like what Mick just posted.....