Hypodermic needles

[Nupi]

Thanks for the tip

[sinclairuser]

Thanks for the tip

no problem mate, i think you should be applauded for doing this, the trouble with this forum is sometimes if is not hobby detector related it gets ignored, there are machines out there that make medium budget hobby machines look like 20 quid toys, even some more expensive machines too, but because they are turn on and go with no discrimination most ignore them or dont even know they exist.
but in pure depth and overall robustness they are excellent, and for those who dig everything and are not concerned with toys or bells and whistles they are way above average hobby stuff, often for the same money or even less.

[green]

i have deliberately sat on the sidelines on this one, getting a hobby style detector to detect needles is quite interesting, some of the comments before by users towards nupi were very unfair i feel, since my ax777 professional detector detects them(commercial machine), its not that big a jump to hobby gear, the thing is commercial machines dont discriminate(usually), they have auto GB, and sat threshold.
they from my tests seem to have more grunt too.
maybe starting from an industrial detector design may give you a boost, its possible that hobby detector designs could be treating the signal in such a way that the odds of detecting hypodermics are stacked against you, what you need is an industrial commercial design to start with, then your successful mods need to be implemented onto that design, though from your vids you seem to be progressing.
the main problem is the type of detector required just dont get posted, most interest is in hobby and homespun projects.

What detection distance are you getting for the hypodermic needles with the ax777?

[sinclairuser]

the company specs say 9"(inches), but in reality mines more like 4"(inches), but that is an improvement over my hobby stuff, i think its about signals, the ax777 detects metals period, while there is no discrimination, a factory mod can give alternate tones for magnetic/non magnetic.
the difference is the ax would detect the rusty smear in the ground never mind the needle, this is a forensic detector after all, 99% of detectorists would find that a nuisance.

[sinclairuser]

i think depending on the detector, old needles that have been in the ground will be easier to detect, because they all degrade, even though they in some cases say stainless, in the western world the use once needles are supposed to be biodegradable, when in the ground over time they expand and delaminate leaving rusty smears.
try it put a couple in a 4" plant pot, and water it to simulate the rain, if you put them in sand you will see the smear, and it happens quicker than you might think.

[Nupi]

Hi, sinclairuser
I've been searching on the official site over the detection of the Adams ax777 but can not find anything about hypodermic needles.
Well over a Disp Razor Blade detection. 5cm does not seem very sensitive. Could you maybe give me a link where I can find more information..
Thanks

[Qiaozhi]

I also checked out their website, and there's no detail on the actual technology being used. According to the specification it states that the current consumption is a meagre 1mA (no target), and it uses a standard 9V battery that lasts for weeks. If you look at the coil, you'll see it's either a concentric or a mono. My suspicion is that it's a pulse induction design (with minimal TX power) in order to be able to sample very early and detect small targets. The fact that it's an all-metal detector also implies a PI.

[sinclairuser]

i will scan the factory spec sheet when i have time, they are very coy about the circuit, i have no doubt that this model now uses pulse induction, the older models had blanks on the board so a disc pot could be fitted, when i asked about this model i was told that only magnetic/non magnetic identification was possible.
the problem for me is its supplied to me from an employer, as such i can only use it, under terms if faulty i must return it for repair /replacement, its due for replacement in september anyway and as i understand it when replaced it will be with a garrett machine(csi pro), adams decided to ramp up prices it seems, which is cheeky as they are actually cheaper to make than when introduced since the chip has changed to an ordinary one rather than the proprietary one in mine.
they have a flaw that mine has not had an issue with in that the power consumption specs are way off, the power circuit in it uses way more power than claimed, i'm sure the specs given are for a fresh battery put in then the unit left in the van, not real daily use as the battery life is about 9-10 hrs continuous use.
what users have done is left them on charge which destroys the battery with memory effect, the supplied battery needs fully discharging then fully recharging to stop this, but since these units get thrown in the back of a van and pulled out for 30 mins work, then thrown back in it has caused problems.
i cured mine by putting a nicad type battery in, this has been more than happy to be charged up in the van ready to go, usually we get the option to buy older equipment when replaced which is usually for peanuts, i intend to keep this and open it up to play with it i have a full bench schematic stashed somewhere allready which the service engineer gave on the understanding i keep it to my self.
i have another one not working that i got at the west yorks police auction, but this is older and although looks the same the battery is 12v and the coil is not compatible, i dont have the schematic for that one so its stashed in the lock up out of the way, i'm hopefull that one is vlf, but i wont know untill i can put them side by side and strip them i also need a schematic(2004 model)
Detector target sheet.pdf
this the one online i have one that is more detailed and specifically quotes needles.

[Nupi]

What I have found are 3 pdfs where ax777 or Adams called but unfortunately was not tested.

Systematic Test & Evaluation of Metal
Detectors (STEMD)


As a result of the laboratory in-soil tests at Ispra it was determined that the Guartel MD8+,
Ebinger 420HS solar and Adam AX777 detectors were essentially unusable on lateritic soil from
Toscana, Italy, due to soil noise. Since it was known from magnetometer survey data that this
soil is not as bad as that encountered in Laos, these detectors were not retained in the trial.
================================================== ====================
Adams Electronics AX777
Adams Electronics is a well-known manufacturer of small handheld detectors for
inspection of persons. Their model AD2500 and the very similar AD2600S small
detectors were included in IPPTC to see if low-cost devices of this type could be used
for demining, simply by attaching them to a longer handle, but the results were
generally poor. Adams does currently manufacture a detector intentionally designed
for ground search, the AX777. Interesting features are low price (312 EUR), low
weight (1.5 kg), vibration as well as audible alarm and long battery life (360hrs
claimed, but not tested by JRC). It is not a purpose-built demining design and a
preliminary assessment confirmed it to be less robust than the demining detectors: the
battery compartment can come open if it is roughly handled and it lacks a
transportation case or backpack. It has no soil compensation feature. Such limitations
are to be expected in a device in this price bracket. For these reasons, the AX777 was
excluded from STEMD but we did conduct some in-air sensitivity tests with it.
Results indicated that it has the unusual feature of performing best at very high
speeds. In-air detection heights for the 10 mm 100Cr6 steel up to 155 mm were found
119
in pendulum tests, which are comparable to those of the SHRIMT Model 90 and the
CEIA MIL D1 on its lower “red-spot” setting, but this performance is only achieved
at sweep speeds of 1 m/s, which would be impractical to maintain in manual
demining. At lower speeds, sensitivity on 100Cr6 and other metals is significantly
reduced. Results of the speed test are shown in fig. A.3 below.

[Qiaozhi]

For those that don't know already:
Lateritic soils contain a lot of iron and aluminium, and they are therefore generally red in colour.
Since the AX777 does not feature a ground balance control, then it's not surprising that it performed poorly in this type of soil.

[sinclairuser]

For those that don't know already:
Lateritic soils contain a lot of iron and aluminium, and they are therefore generally red in colour.
Since the AX777 does not feature a ground balance control, then it's not surprising that it performed poorly in this type of soil.

absolutely, its only the use of this thing professionally that has endeared it to me, i kind of fell for it to be honest, that price quoted in the document nupi posted must be a special price, they are 599 quid direct from adams uk for private buyers, i have been told we are getting the csi pro's for a bulk price of 499 each plus vat, but i dont know the quantity involved.
i was'nt championing the adams in any way just giving my experience with it, the whites 3900 pro plus is much better and only costs 239 pounds delivered, it also has GB, and discrimination.
i was mearly wondering if trully profesional detectors as compared to hobby stuff might be better in this instance.

[WM6]

Thanks WM6,
I do not know what exactly you meant. With the Smart,
It depends on the soil and in particular of the humidity. If you go from dry sand to wet grass,
then you have to adjust. In general, he does not like wet grass. I have not tried in highly mineralized
soil but in a bin with wet beach sand (salty) I was able to detect the needle. I will soon make a video.But with my homemade md I have no soil tests done, that's early yet.

Thanks for additional info nupi.
You described usual phenomenon that appear in development phase.
I am sure you will overcome all unwanted emergencies and at the same time preserve or even improve sensitivity of your innovative solution.
I just asking if you sense some drift after say 10min of work in field without changing soil conditions?

[Nupi]

I have not yet observed any drift. Do you expect it?

[WM6]

I have not yet observed any drift. Do you expect it?

This is really gratifying. Stable work mean less problems in final development for sure.

Usually extremely narrow filtering in analog design (if your solution is analog) are accompanied with some drift. Your achievement is really encouraging.

[Nupi]

Thanks WM6.
It is indeed analogous, but if the filters are coupled synchronous to the oscillator then it does not matter
that the oscillator is slightly drift from the frequency.
In the video "Filter test 2" you can see such a filter in operation.