PimentoUK

Are we to assume the '900' will have 9 modes, just one more than the '800' model ? I would guess 'All-Metal' is the obvious missing one, and easiest to implement. That may disappoint those wanting a '1200' or '1600' model. [ though the mighty power of mathematics also allows for a machine with 9 modes such as Park1/2/3; Field 1/2/3 ; Beach 1/2/3 ... but not that compatible with the existing LCD display, unless you 'illuminate' both Park1 AND Park2 for the third mode. ]

".... train the ears" I think the important bit here is the S of ears. If the audio was seperated in a frequency-dependant way, there's likely to be more chance of picking out nuances. This could be done with the existing mono output and post-processing, though it would evidently be better if it was performed internally by the Eqx software.

"A rectifier diode of some sort? Not quite sure what that's doing in a simple 8 cell AA pack" It's wired from the + of the charging socket to the + of the battery. It conducts ( forwards biased ) when the pack is charged ... but importantly : it prevents discharge via the charging socket, if something metallic gets in there accidentally. It's a pretty standard safety precaution.

I think it's internally very similar to these "USB Power Bank" devices, except probably slightly tweaked to give 6 Volts instead of 5 Volts output. Many power banks actually give out 5.3 - 5.5 V , probably to allow for a bit of drop on the cable, so it's possible it's running exactly like a power bank, same electronics.

I'm pretty sure the RNB pack has a voltage regulator in it, to set the output at 6 Volts. The actual battery is likely to be 3.7 Volt ( nominal ), a typical Lithium cell voltage. So the battery may be charging correctly and fully, but when you try and discharge it, via the regulator, it fails. Or the battery may be faulty, hence not charging or discharging correctly. Or the charger may be faulty, and it's indicating it's done it's job but in fact hasn't. Presumably it's covered by some warranty/guarantee from the manufacturer or seller?

As Nok-Mak have a good reputation with regards to customer relations, it may be worth asking them about the scaling of the Ground Strength meters for the particular machines you're using.

To help understand what these 'ground strength' / Fe3O4 / mineralisation meters are showing, it's worth a read of a few posts on the "Equinox improvement ideas" thread, starting from this post: Notice the scaling of the F75 bargraph is logarithmic, to handle the wide range of possible values, and observe that it's not that precise, it goes in roughly factors of 3 increments, so there could be a 50% discrepancy between two different machines, and you wouldn't see it. This makes comparisons harder.

The 'notch' feature on the F75 is a nuisance, and it is easy to accidentally set it wrong, and not realise. I recommend performing a 'Factory Reset' , see the Owner's Manual for details of how to do this. This will clear any peculiar settings you may have got. I notice the central foam piece from the armcup is missing, that is unusual. Also, on the genuine machines I have seen, the 6 bolts that hold the upper armcup to the lower section are painted black, not left shiny silver. This makes me suspect the machine is counterfeit.

Hmmm. I did say 'Nothing really to do with hotness' ... which probably doesn't translate transatlantically. It means: 'not much to do with hotness'. Hence my statement giving an example of one common correlation: - strong ground ,and '90' GB ( machine dependant) So ... I'll try and explain it. Ground signal comprises two components: A 'Zero degrees' component, caused by the microscopic iron and rusted iron that is spread throughout the ground. A '90 degrees' component, that's attributed to the electrically-conductive minerals ( carbonates/chlorides/sulphates etc ) dissolved in the water in the ground. These two add together, in Vector fashion. Meaning there is one ground signal, that has a phase relationship to the detectors transmitted signal. It's possible for the detector to measure this amplitude, and the phase. This is often done by resolving the single ground signal into its two constituents, 'zero degrees' and '90 degrees' , then doing some mathematics. The phase is ( after some manipulation ) what is presented as Ground Balance' . The strength of the 'zero degrees' signal is presented as the 'mineralisation strength'. As examples: *Mild ground ,typical UK stuff: 'Zero degrees' = 10 units; '90 degrees' = 2 units Phase is 11.3 degrees, GB display reads '70'. Mineral bargraph reads "1 bar, 0.03% magnetite" ----------- *Tennessee devil dirt: 'Zero degrees' = 1000 units; '90 degrees' = 2 units Phase is 0.11 degrees, GB display reads '89'. Mineral bargraph reads "5 bar, 3% magnetite" ------------ *Some weird salty ground, maybe where "Monte" lives 'Zero degrees' = 35 units, '90 degrees' = 35 units Phase is 45 degrees, GB display reads '40' . Mineral bargraph reads "2 bars, 0.1% magnetite" I hope that made sense ( and I hope it's reasonably correct, I don't want Carl moaning too much ).

I finally got the opportunity to test the foil hat at the farm field with the microwave tower nearby. Unfortunately, it was a fail. Absolutely no EMI reduction could be seen with the hat fitted, and grounding the hat had no effect. The 'strategy' of placing my body between the control box and tower still worked reasonably, I'm still optimistic that there's a solution somewhere. Obvious problem: My foil hat is just that - there's a dirty great open hole at the bottom, that is an easy entry for microwave signals. So I will try and do the simplest experiment and just use a sheet of regular kitchen foil wrapped around as much of the control pod as practical. I can also easily join it to the detector ground with my dongle. Another unknown is the internal wiring to the circuit ground. It's not inconceivable the ground on the USB port has EMI filtering on it, thus seperating it from the true circuit ground at RF frequencies. Hence connecting to it has no effect. Unfortunately, accessing the ground pin on the coil connector is not so easy. I have M12 plugs and sockets, and could make a short extension that would give me access to that pin, I've got to be neat, though, as the extra cable could just as easily make EMI pickup worse. There's also the possibility of putting a proper braided wire screen on the coil cable, and joining it to circuit ground with the extension cable. Another oddball idea: as my body will absorb EMI , can I improve 'body shielding' somehow. I have some foil-backed foam sheet that's for thermal insulation purposes. Could I fit a sheet of that stuff inside my coat ? I could easily hold it in front of the detector. It's a reflector, though, not an absorber, so may not be what's needed. Do I put the foil sheet on my back, or on my chest? Which brings up the business of RAM : radar absorbent material. You've seen those photos taken inside EMI test rooms, where the walls are lined with spiky foam tiles, to absorb RF energy? They're made from carbon-loaded foam, so they conduct electricity, in a bad way. What they don't absorb is reflected, and the odd shape of them means the reflected RF gets spread around, and bounced onto another bit of the foam, to be re-absorbed, etc. So .... another experiment would involve using conductive foam sheet to cover the control pod. Experiments I've done in the past showed that those black plastic bags used for electrostatic protection of electronics boards/computer hardware etc are not very good conductors: good enough for their design purpose, but not much else. So not suitable for shielding. But the 'crunchy' foam used for storing computer chips is better.

I've just downloaded the Anfibio user manual to see what they say about the mineralisation meter .... they basically say nothing. It has 5 bars, and it wouldn't surprise me if it closely followed the F75 scaling, two bars per decade, and similar scaling. However as it's a selectable freq machine, you need to consider which freq is being used, and then consider if N-M recalibrate the scaling when the user changes freq, or does it give a different reading for each freq? And re: GB values .... GB has nothing really to do with 'hotness', though it's probably true that 'hot' ground has close to zero phase lag, hence reads '90' on an F75 ( and probably other machines with that GB scaling ).

The '14 chips' are analogue switch circuits, general-purpose cheap CD4053 types, widely used for sampling signals, and frequently used in the demodulator stage of many VLF machines. 3 switches in a package, each one single-pole changeover: https://www.ti.com/product/CD4053B the nearby IC's look like op-amps, two amps per package.

It was an introductory explanation, you really need the opinion of folks who actively do tinker with GB settings. I can't comment on the video, really, I've never hunted on a saltwater beach. I do recall from discussions on Tom D's forum, that having the correct GB setting becomes more important the stronger the ground signal is. This also means that how far above/ below ideal GB you go will vary with the ground. In mild ground, you may adjust it from 65 to 75 and see no difference. In strong ground, 69 and 71 may be the useful tinkering range.

For the benefit of most of us who have never used a Kruzer, this is the pdf of the operating manual on NM's website: https://www.noktadetectors.com/wp-content/file-download/kruzer/manuals/kruzer-user-manual-en.pdf A quick scan shows that it very closely copies the GB readings and range of the Fisher F75 / Tek T2 ( probably intentionally ). So '90' is your safe setting, balanced to ferrite. It will adjust to '99' if you need to quieten down troublesome ground, and adjusts to '00' for very salty beach conditions. '90' would be OK for zero mineral/iron conditions, like clean freshwater sand beaches. It's also where dirt with very strong iron will GB, where the iron vastly outweighs the mineral component. So ... setting Mr A's machine to '75' should give less sparkiness, but less depth, I'm thinking the 'lowest conductors' will be worst affected. And setting GB to '67' etc will make it sparkier, but the benefits ... hmmm not so sure. Likewise, I'm not so sure what misfortune will afflict the machine if you set it to '50', for example. Be aware the 'F75' scaling of GB is GROSSLY non-linear, for user convenience. '90' through to about '45' represents probably a ground phase of Zero through 25 degrees lag, respectively. The range '45' to '00' represents 25 through 90 degrees lag. ( my opinion, based on using an F75 and tinkering with it ) Over to the experts ...

I used to mark several targets, then go back and dig them, particularly when I was detecting woodland. I found that concentrating on the detecting was beneficial, and the repeated interruptions of digging spoiled my 'rhythm' . I don't do it so much now, though I always carry a few markers with me, for difficult situations like multiple nearby targets, or to help pinpoint weak targets more precisely. They also help in poor lighting, where 'spotting' the ground is harder. I too found fluorescent pink to be the most stand-out colour, as it doesn't occur in nature. White would be my second choice. Bright yellow and orange are easily lost among fallen leaves. But I use cardboard markers, as they are biodegradeable, and unlikely to harm any animal that may eat them. I tend to lose them on a regular basis, somehow, so this is a wise choice, I think. Mine are typically cut from packaging like cereal boxes etc , about 60mm / 2.5" diameter.

Here in the U.K, all the major Minelab dealers ( Crawfords, Joan Allen, Detecnicks ) sell them, normally as a pair, so I would assume the US dealers would similarly list them.

It's only pure gold that's a good conductor. When it's alloyed, the conductivity drops quite significantly. Even 22 carat ( .917 fine ) has a conductivity that is one-fifth that of pure gold. And lower carat alloys often have nickel in the mix, which is particularly bad for conductivity.[ copper-nickel alloys are used to make electrical resistance wire, for heaters, kettles, electronics resistors] Here's a table of different metals and their conductivities: http://eddy-current.com/conductivity-of-metals-sorted-by-resistivity/ Finding good data on gold alloys is hard, no-one is usually bothered about the electrical characteristics of jewellery, unsurprisingly. 22 carat gold is very close to pure tin on this scale, about 15% IACS. Over on Tom Dankowski's forum, I posted about my attempt to make 'dummy' US 0.900 fine gold coins from tin. I used a 'lead-free' electronics solder, which are usually almost pure tin. The results were pretty close, but without any real coins to compare with, my project stalled.

Importing from the US will cost you: ( in addition to the item cost and postage charges ) 9% import duty on the item price 20% VAT on ( item price PLUS postage charge ) £8 British Pounds fee charged by the Post Office for handling the VAT/duty money. Then there's the other stuff related to exchange rates, ie there's actually two rates, bid and offer, and the 'headline figure' is the average of the two. And how you choose to pay matters, PayPal / credit card etc. A quick calculation indicates 6000 Dollars becomes 5750 Pounds.

Interestingly, I recently had an example of the model on the left, I found it dumped near a recycling paper/bottle-bank site. So for fun, I brought it home to perform a strip-down. 99% of it went in the bin, the most useful part was the PP3 9 volt battery connector. The bizarre bit was the LCD display. It did nothing of note, and clearly its sole purpose was 'hood ornament'. Yet there was way more tech in this LCD than the rest of the machine, it had some multi-segment 'pie-chart' appearance, that cycled round when (presumably) metal was under the coil. There were two cob ( chip on board) integrated circuits to drive the LCD, yet the rest of the detector had just 5 transistors total. It's quite bizarre that the designers have gone to so much trouble creating this useless contraption, when they could've actually made something that genuinely worked, in a simple way.

"1) the original Equinox' control box has its battery inside the handle...and the handle is molded with the control box at its base. I assume that the modification we're talking about is putting the Equinox control box in an external "open/close" waterproof enclosure like the ones you linked" Correct. "... but without the handle...right?" No.o.o..o...o.....o......o The control pod stays complete. Just unbolt the 4 bolts securing the lower clamp part, and you're done. For compactness, you could use it without the lower clamp. Or you could obtain a short length of 7/8" tube ( old detector; hospital crutch ) drill a 9.1mm hole in it, and clamp the handle to it. You will observe the tube presses on the battery-cover, helping secure it, so it's probably better to do this than rely on the tiny screw alone to retain the battery. "2) regarding the coil & headphones connections: snippety-snip....Am I right?" Yes. I don't see any temperature issues. But you need to watch the water and humidity. I presume silica gel dessicant is one solution, there's probably plenty of alternative products, it's not something I have much knowledge of.

"Did you happen to try different modes? Also, I am using hard wired headphones " I didn't try anything other than Park1, I knew that mode gave plenty of EMI pickup, so was a good choice for the 'hat test'. I tried with wired headphones, and using the internal speaker, and there was no difference ( other than a funky metallic rattling as the hat sang along with the detector sounds. )

"I believe that even an "open/close" waterproof box (without any buttons or original control box modifications) could be a solution, since I could have my settings already preadjusted before going in the water and no need for further adjustments while snorkelling" Yes, that was what I was thinking of. "The thing is that: 1) I have to find or somehow make a suitable sized box" You will be needing an IP68 rated enclosure, there is more than one type, so you should read up about the IP rating , some are rated for one hour, some for continuous submersion. Here are a few ideas to get you started: https://uk.rs-online.com/web/c/enclosures-server-racks/enclosures/general-purpose-enclosures/?applied-dimensions=4294885296,4294847133 https://uk.farnell.com/w/c/enclosures-racks-cabinets/enclosures-boxes-cases/plastic-enclosures?ip-rating=ip68 https://www.bopla.de/en/enclosure-technology/product/bocube.html "2) I need to pass & re-screw the coil's & headphone's sockets οut of the box in a watertight way" You will need to make a short coil extension cable, such as a 90 degree free socket to plug into the Eqx, and a chassis-mounted plug on the case. I can help you sort out the connections, wiring etc. The headphone connection is easier. Any old stereo 3.5mm plug to fit the Eqx, and your choice of 3 or more pin waterproof connector on the case. ( I suggest more than 3 pins, it gives you options ) "3) to put the battery also inside the box" ?? Unless you were wanting an additional USB power bank inside, for when your Eqx battery dies ? Or a seperate battery to power a bright 'locator' LED ? Or a flashlight on the coil shaft?

I'm not a water hunter, so I'll limit my suggestion to this: If you have engineering skills, you could re-house the Eqx control pod in a watertight housing, then chest-mount it, and use a custom rod/shaft for the coil,( I suggest using the 6" ).

I got the opportunity last night to sneak out to a local public park that has bad EMI, that is caused by a large water tower bristling with radio antennae. Unfortunately, not the result I was hoping for. The foil hat made absolutely no difference to pickup - that's with or without the circuit ground connection in place. I also tried varying the coil height and with the coil sat on the grass, the EMI dropped a bit, compared to 1" / 25mm above the ground. This pretty much confirms that in this location, it's the coil that's picking up all the interference, none is directly entering the control pod. The farm field that has the microwave tower at one end is a muddy swamp at the moment ( like most of the UK currently ) so that will have to wait a while before testing there. This is the important location, as the field has given up some good finds, many of which are small and 'low conductivity' , and I'd like to run in Park2/Field2 , but that is more EMI-prone.

"I have my Equinox 800 set up ....... and the frequencies are right: 5, 10, 15, 20, 40kHz" That's creative advertising, It runs at 7.8kHz, 18.2kHz and 39 kHz in Park & Field modes, Beach has an additional 13kHz in the mix. I also think a "New CZ" should be 5-tone, not 4-tone. If they were adjustable, you could set it up to behave like a 4-tone machine, anyway. Also, they should drop the "CZ" name ... it may work for you US guys, but elsewhere in the world, "see-zed-five-dee" is unmemorable, and could be a spare part number for a washing machine.