AlgoForce E1500

[phrunt]

I have a variety of ground I can try it out on, from extremely salty inland gold ground, to the blackest of black sand beaches, but you're right, it's best to get some feedback on it from various locations.  I'm lucky in a way that many of the gold areas I detect have relatively mild soils, although I've yet to bother taking a detector with a mineralisation meter to see just how mild it really is, I'm just going by the fact I can get away with running a GPZ in normal, and a GPX in sensitive extra in many spots. 

What I do know though in many places VLF's lack a lot of depth in gold areas that they obtain in park like settings so it's probably not as mild as I think.   I'll take a mineralisation meter detector with me to check next time I go such as the Deus 1 or Teknetics T2 and see how bad different locations are.  Something we do have here though, is plenty of nasty hot rocks.

[Joe D.]

Between you, Phasetech, and a few others, we should have some videos soon !🍀👍👍

[BigSkyGuy]

I think I understand what the conductivity meter is, based on one of Steve's comments regarding GBPIs. Because PIs are time domain, that is the only information the E1500 has to go on (as far as I know). So what I think the number is dervived from is the return time of the pulse. Short returns = low numbers and long returns = high numbers. Because the return time roughly correlates with conductivity, it is referred to as a conductivity scale. The question is, how much overlap is there between nails/small iron and low conductivity targets and large iron and high conductivity targets? I suspect alot. I see the conductivity meter as potentially more useful for the coin hunter than the relic or nugget hunter. The reason being, a specific coin may have a distinct conductivity number that can be targeted. For instance one could dig the numbers corresponding to dimes and quarters while digging any iron that happens to fall in the same conductivity region. I think this would be harder to do for nuggets and relics due to the large range of possible conductivities.

Another tell, may be in the pinpointing, as stated in the manual:

The target id is also useful for assessing shape. If the target ID fluctuates significantly when the coil is moved slightly off but still above the target, it likely indicates an irregularly shaped target, such as a bottle cap or nail with a large head.

If the E1500 has audio nuances (such as double beeps for iron) maybe some additional iron can be eliminated as well. Without knowing how many pulses per second (pps) the E1500 puts out it is hard to predict how much audio information we will get. My SeaHunter Mark 2 has 750 pps and has very little audio information to my ear, while the Impulse AQ has in the thousands (I don't remember the exact number) and double beeps on some iron. If the battery size is any indication, then maybe the E1500 will be closer to the SeaHunter than to the AQ in terms of pps. Time will tell.

Another thought regarding the GBPI with dual tones and the E1500 is the possibility that different programs will give different numbers on a given target. If so, one could potentially check a signal in two different programs to get a better idea of ferrous vs non-ferrous. If the conductivity is normalized between programs, like phase-based TIDs are, then this would not be possible.

[Chet]

Time constant/conductivity properties extracted from Minelab document below; 

Metal detectors may differentiate between different non-ferrous targets by measuring how well eddy currents flow in them. This is determined by a target’s “time constant,” but is often referred to as “conductivity”, which is not a suitable term as conductivity is not the only property of a target that determines its time constant.

     Two properties of a metal target determine its time constant. One property is called the target inductance. This inductance may be thought of as the effective “mass” of the eddy currents, and which is basically the size of the eddy current path. Thus, for a given eddy current flow, the bigger the effective target inductance, the bigger the “momentum” of the eddy currents.

     Another property is called target “conductivity,” which is a measure of how easy it is for eddy currents to flow. This is the opposite of electrical resistance. High conductivity (low resistance) means the eddy currents flow easily (low current “friction”). Low conductivity (high resistance) means high eddy current “friction.”

     The better the target conducts electricity and the bigger the inductance, the longer the time constant. That is, a high eddy current momentum with a small slowing resistance, like a heavy vehicle with low friction, takes a long time to stop.

     Conversely, the poorer the target conducts electricity and the smaller the inductance, the shorter the time constant. That is, a low eddy current momentum with the resistive “brakes” hard on, like a light vehicle with high friction, takes only a short time to stop.

     Time constants vary very considerably between targets. Small bits of aluminum foil have very short time constants whereas, for example, gold ingots have a much longer time constant.

     Here is a table of targets of increasing time constants (from short to long):
 small bits of aluminum foil
 fine jewelry chains
 small old Roman coins
 US dime (small 10c coin)
solid US civil war bronze belt buckle
solid Bronze Age axe head
large gold ingot
large thick copper or aluminum plate

     Gold nuggets cover a very large range of time constants, from very short to longish. However, it should be noted that even large gold nuggets mostly produce relatively short time constants compared to similar sized man-made metal targets of high conductivity, because of the way gold nuggets are formed; they have many voids and impurities which significantly reduce conductivity and inductance.

      The magnetic properties of ferrous targets cause them to have a high inductance. This is because the magnetic field created by the eddy currents is made stronger by the magnetic property of the ferrous targets. In effect, this “amplified” magnetic field makes the inductance of the target higher. So, even though most ferrous targets may have poor electrical conductivity, they usually have long time constants because of their high inductance.

     Only pieces of steel or iron that have almost completely rusted through, or extremely thin steel wire have short time constants 2 (e.g. highly rusty steel/iron flakes or very thin staples.)

     However, some mildly ferrous targets may also have short time constants, e.g. some mildly ferrous coins or weakly magnetic stainless steel, and some plated steel targets too.

    The most common discriminator setting is to discriminate against ferrous targets and the shortest time constant non-ferrous targets.  

Extracted from page 4 & 5 of the following Minelab document; 

http://www.minelab.com/__files/f/11043/METAL DETECTOR BASICS AND THEORY.pdf
 

[jasong]

I agree. I posted something similar with regards to how this discrim must be working earlier in the thread.

We are used to hi/low. This is probably doing something similar to taking it from 2 discrete notches to 100. It's gotta be highly dependent on geometry as well as conductivity if so. But still, in some areas I can be about 90% certain that any low/hi's are not nuggets due to size alone, so having 98 more numbers to use may be even more useful if a guy understands what they mean, might be able to reduce even more the chances of leaving larger gold behind. 

For that reason a person is probably going to have to test the discrim out on a very large range of targets and ground types to really understand when/where to use it and when/where not to trust it.

Bits of tin will be tough if so, due to varying size and rust levels. But things of constant geometry and material consistency like shell casings or bb's may fall into a specific TID range that may or may not overlap with common nugget ranges (unfortunately, they are not symmetric, so orientation will be a monkey wrench in the gears, argh). Being able to eliminate 50 cal training casings, common hunting and plinker casings (.22, .223, 30-06, etc) would save a lot of time in some places. 

If this is how it works, I intend to do something similar to what Strick did with the Manticore and test these common target types along with a range of nuggets at different depths and soil types. Because if the discrim works it seems like it'll be ultra important to understand exactly how and on what, and when and where to use it. There are definitely times it pays way more to selectively choose to miss some nuggets by avoiding low probability targets in order to gain exponentially more time digging higher probability targets. 

This is what I'm really curious about testing. Unfortunately in NZ they just don't have this amount of firearms debris to find and test with. Simon has a lot of shotgun pellets though for sure, and the BB's vs nuggets and any potential overlap in the 0-99 scale will be very interesting to see at least. 

[goldenoldie]

3 hours ago, phrunt said:

 I'll take a mineralisation meter detector with me to check next time I go such as the Deus 1 or Teknetics T2 and see how bad different locations are.  

One good thing that the QED had through the use of its MGB adjustment to complete a Ground Balance was to give a figure / number reading on its screen for the type of ground, that being the higher the figure / number reading the more mineralised the ground.

[Prickly Prospector]

A bit left field, But would ML have raised it's prices knowing this was coming, and possibly have their own budget machine for the same price range? Pure speculation, but many here have their ear to the ground.

[Norvic]

3 hours ago, goldenoldie said:

One good thing that the QED had through the use of its MGB adjustment to complete a Ground Balance was to give a figure / number reading on its screen for the type of ground, that being the higher the figure / number reading the more mineralised the ground.

Aye it is a top feature, the Axiom is another PI that has this very handy feature, the changing ground reading can be a top 'nugget' visual indicator along with the change in ground noise reading once you`ve familiarized yourself with these readings in the ground you prospect. In particular I`m keen as to see how the 'vibrations' pan out, maybe 'feel' sense can be proven to be as effective as hearing, especially for us deaf oldies.

[Prickly Prospector]

4 hours ago, goldenoldie said:

One good thing that the QED had through the use of its MGB adjustment to complete a Ground Balance was to give a figure / number reading on its screen for the type of ground, that being the higher the figure / number reading the more mineralised the ground.

Unfortunately, upgrades saw the GB readout become superfluous with the GB range and centre changing with each new upgrade. Rudimentary tracking that was being tested may have brought it back into play with the figures moving as you detected. Unfortunately this has never made it to a standard for customer release, and to my knowledge is still being worked on. I think the QED missed it's chance.

 

[phrunt]

My ground balance numbers using the AGB never worked on my QED, they never really changed, I was told it was because my ground was mild, yet it didn't do anything much on a black sand beach either and certainly didn't balance, I just did it manually in all scenarios.  I found the numbers pretty pointless and not an indication of anything.

As for my Algoforce, it's now on its way, I paid today and have tracking, with any luck it will be here within a week.