PI Detector Depth

[QMaze]

This isn't a thread about which detectors go the deepest but more how deep does the PI technology actually punch through the ground? When it sees a target does it then immediately send back a signal and stop at that depth or send the signal and continue punching deeper. I'm just curious.

 

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[rick67]

Quote from Hobby Hour.
Pulse Induction (PI) metal detectors are sending repeated pulses of electrical current to the search coil, producing a magnetic field. The coil transmits a pulse toward the ground, generating an answering pulse from the target object. A sampling circuit measures the pulse and sends it to an integrator, which generates an audio tone.
PI outperforms the VLF/TR in areas where little trash is located, on saltwater beaches or mineralized ground, since they are capable of ignoring both conductive salts and mineralization simultaneously.
Pulse Induction detectors are able to detect objects buried deep underground, but they are sensitive to iron and do not have the ability to discriminate against different types of metals. This flaw makes their use on inland sites extremely difficult.

 

[Terry Soloman]

As with any other detector, it is about transmitting power. A Minelab GPX 5000, equipped with a 20" x 40" "Mothership" coil can punch down to around 50" on 1-ounce and larger targets.

 

[LawrencetheMDer]

Most MDers would agree that PI machines can go deeper than VLF or multiVLF machines (also called broad spectrum detectors). However, there is more to metal detecting than depth, namely discrimination. Who wants to dig every detected target no matter the depth? I've seen people on the beach dig 3-4 foot deep (and wide) holes to recover a fish hook. I have better use of my time. In addition, if you're MDing in the surf you can't dig deeper than about 12" as the hole will simply fill-back in with the next wave. So, discrimination is essential under many or most circumstances. Most importantly, it is essential to discriminate against ferrous metals (ie iron) since it is everywhere and usually of little value. Personally, I favor a multiVLF machine with excellent stability near or in the water and a machine with excellent discrimination abilities.

 

[Terry Soloman]

You can't nuggetshoot with a multi-freq VLF machine. They also don't work well for meteorites.

 

[QMaze]

If you live in an area that is fresh water would you still get a PI for beach hunting ??

 

[QMaze]

You can't nuggetshoot with a multi-freq VLF machine. They also don't work well for meteorites.

Meteorites are picked up by PI detectors, cool.

 

[Terry Soloman]

If you live in an area that is fresh water would you still get a PI for beach hunting ??

Not if it is a freshwater beach!

 

[Mach1Pilot]

While many of your PI machines used on the beach don't have a discrimination feature, some of your higher priced ground balancing PI machines do have the ability to discriminate.. but nowhere near the degree found on VLF detectors. Usually you are listening for an iron tone, a low conductive tone, a high conductive tone or some combination of all three. That's about as good as it gets in today's market. The best discriminators are the Minelab GPX series, followed by the Garrett ATX, White's TDI and the Garrett Infinitum.... lots of relic hunters use these machines in military encampments where you want to dig everything non-iron (plus some of the iron too)

Their ability to virtually ignore mineralization certainly helps too in the raw depth department... But also a lot of the advantage is in the very large coils sometimes found hanging on the front of these machines.

 

[QMaze]

Good info, thanks.