Willy

No This iron reject procedure should be made on the spot you are going to survey and not at home before going there. The ground type influences the results. The warm-up does not changes the conditions as much as the ground.

This extract was indeed taken from an early version of the manual. I do not know if this 'tiny' mistake is still in there. In the certification document: 3. US Nickel Depth min. = 15.5 inches (in factory)4. Gold Ring Depth min. = 16.5 inches (in factory) 7. US Nickel Depth min. = 16 inches (air test)8. Gold Ring 18K, 2.7 grs, size 8, Depth min. = 17 inches (air test) Note the word 'min.' in the QC results. The QC tests are made on the PCB alone on a test bench and during the functional tests at the end of the assembly line by QC personnel. They expects a CLEAR SIGNAL response and the tests are made in a noisy (both EMI and external sound) factory, not in the field. The purpose of this test is to certify that the whole system gives its MINIMUM specs, not its MAXIMUM specs. They are not detectorists. A real detectorist using a good quality headphone would react on much less clear sounds. The real practice has proven that these specs are extended by one or two inches in fair ground and in the hand of a real detectorist. So, please do not jump to too early conclusions☺️😉

That little nail in a capsule is indeed routinely used for the iron reject tests during the functional certification of the Impulse in factory but the main reason why it is joined in the package is to be used by the user as a common iron reference target when adjusting the tone/mute modes in the field before starting a session in disc mode. The operator manual defines the correct iron reject adjustment using that 'reference iron target'. This is the best procedure to get the most of the iron reject function. (see extract below) The capsule is there to avoid the nail to rust and react differently over time. 5.7 REJECT Control The REJECT control determines the amount of iron rejection. It applies to TONE, MUTE, and VOLCANIC SAND modes. A high REJECT level also rejects high conductive targets like larger silver coins; rarely even gold items (such as a large heavy ring) can fall in this range. REJECT should be used only when there is an abundance of iron. REJECT is best adjusted with an example target you want to reject. A sample iron nail is included with the Impulse AQ Limited. 1. Choose TONE, MUTE, or VOLCANIC SAND mode. 2. Set the REJECT control to 0 and the ATS control to 8. 3. Put the reference iron target on the ground in horizontal position. 4. Swing the coil over the target at a height of around 3 inches while slowly increasing the REJECT control. 5. Stop when the nail responds as follows: a. In TONE mode: the iron response is mostly low tone with some minor high tone mixed in. b. In MUTE mode: the iron response is mostly silent with some minor high tone breaking through. c. In VOLCANIC SAND mode: the iron response is fully silent which is necessary to reject volcanic ground. 6. Optionally, test a US nickel to verify that it gives a high tone. In setting up iron rejection, both the ATS and REJECT controls affect each other and should be mutually adjusted to achieve the desired rejection responses. It is highly recommended that rejection is set in the field using test targets. (see Expert REJECT control) NOTE: The REJECT feature of the IMPULSE AQ does not function in the same way as the discrimination control on a VLF detector. It provides variable audio masking of iron targets as well as high-conductivity targets. Also, unlike some PI detectors, there is no target hole. 5.8 Expert REJECT Control (ATS + REJECT) 1. Choose TONE, MUTE, or VOLCANIC SAND mode. 2. Set the REJECT control to 6 and the ATS control to 0. 3. Put the reference iron target on the ground in horizontal position. 4. Swing the coil over the target at a height of around 3 inches while slowly increasing the ATS control. (Your setting is normally arrive near the position 8, between the position 7 and 😎 5. Stop when the nail responds as follows: a. In TONE mode: the iron response is mostly low tone with some minor high tone mixed in. b. In MUTE mode: the iron response is mostly silent with some minor high tone breaking through. c. In VOLCANIC SAND mode: the iron response is fully silent which is necessary to reject volcanic ground. 6.Finally refine your setting, decrease the REJECT button to obtain an iron response low tone with some minor high tone mixed in. 7. Optionally, test a US nickel to verify that it gives a high tone. In setting up iron rejection, both the ATS and REJECT controls affect each other and should be mutually adjusted to achieve the desired rejection responses. It is highly recommended that rejection is set in the field using test targets. NOTE: Your IMPULSE AQ takes about 10 minutes after start up to stabilize in temperature. Consequently after this time it is recommended to re-adjust the settings slightly.

The main heat generators are the MOSFET and the damping resistor. The MOSFET has been carefully selected for its low RDSon and to sustain the high flyback voltage. Just the JOULE's law (W=RI2), large current even in low resistance--> heat This is the price to pay for a powerful PI with the current technology. The switching power supply itself does not generate heat. Thus, no worry about the long term reliability on that subject.

It was designed like that but there is no protection circuit in the enclosure, it was inside the battery pack.

It would probably more or less work BUT you will loose quite a few inches and possibly loose a few µsec of pulse delay. The design of the Impulse coil has been specially studied to cope with small pulse delays and EMI protection and still kept light. Its production in series was carefully setup in order to generate constant specs in values of R, L and C. with thorough measurement at various phases of the production line. The measurement data is recorded for statistical reports. This is unusual in the coil production of the detector industry.

The ideal coil would be made of a flexible material like rubber (or chewing-gum!!) so that the user could change its diameter at will to make it perfect for all environment cases. In this case, you could have your own perfect coil, 12.5",12",11.5",11",.... down to 2"!!! Sadly, this is not (yet) possible with the current technologies😢😢

Putting things straight about batteries (specially Li-Ion) for the AQ (or for any portable device) Three different cases: Independent battery cells They are charged in parallel, the charger takes care of each separately in terms of current and voltage, automatic balancing Protected cells (a BMS circuit in EACH cell) These cells are slightly longer than the non-protected ones, the BMS is at the top. Highly recommended!! Unprotected cells NOT RECOMMENDED ( no protection against over-voltage, over-charging, over-current including short-circuit, thus, potential fire and explosion due to the Lithium) Battery packs (A BMS circuit integrated in the battery pack) For all the certified battery packs, a single BMS takes care of the battery cells separately. The charger connects to the BMS and not to the battery cells. The discharging current and voltage are defined by mixed configurations of nSmP (n Serial Cells to increase voltage, m Parallel cells to increase capacity) The initial design of the AQ was using a LI-ION BATTERY PACK (with integrated BMS) permanently sealed in the battery pod. Due to certification problems and high costs, this technology was replaced by a Ni-Mh pack which does not require as much care for airline shipping The final AQ version and the GOLD version will be shipped with good quality protected Li-ION battery cells as defined in above case 1.1. It will not be possible to use the SHORTER non-protected cells.

In the VLF world, it is generally admitted that the maximum detection depth is directly proportional to the coil diameter. It is evaluated at a depth about equivalent to the diameter for a concentric coil. In the PI world, the equation is probably different but still directly proportional for the same target size, shape and material. The detection range is a cone sticking out under the coil. A large coil generates a longer (thus, deeper) cone but its tip is also larger making the pinpointing more difficult. A smaller coil is better adapted for highly ferrous-polluted ground because its more precise detection cone Real experiments in real ground and sea water will tell.

Indeed, he did that before but now, he has no time left out from his R&D work on the GOLD version and on the support of the production start-up of the AQ.

Indeed.

Smaller coils are easier to swing in water and in rocky grounds. It also better picks up the small targets and is easier to pinpoint. However, the detection depth is indeed reduced. Again, you can not have your cake and eat it.

That does not depend on Alexandre, El Paso decides what and when to deliver to Rick.

I can tell you that the AQ will get a 8" coil. The GOLD will also have one (yet not interchangeable, different number of turn!!) This will possibly be offered as an option to the LTD version as well. There are already a few of them (as prototypes) out in the wild under field testing

No problemo😉 Pointed questions or remarks can only generate progress and new ideas. I know the whole history of that project from its beginning when it was still named 'Manta' back in 1990. Since then, Alexandre and I have worked in closed team complementing each other with our respective technical backgrounds. I still keep in close contact with the Impulse project (and with El Paso) while working on my own project(s) and I am happy to answer any technical question posted on THIS forum if it does not infringe the NDA I have signed with FTP.

Yes, it stays outside of the connector but that was deemed to be unbearable by the reports of early testers. The change of connector resulted in it sensitivity to local capacitance variations. (You can't have your cake and eat it ) There was even an electrolysis effect on the surface of the metallic upper shaft with a nasty looking result. This was also replaced by the current plastic-made upper shaft.

This is the recipe to catch the deepest targets. The good stability of the Impulse and its variable pitch audio coupled with a good-quality headphone (with well external sound-isolated earmuffs) enable the user to capture those little variations of sound in a threshold adjusted to slight feedback.

Nothing to laugh at. This is the way to make good brainstorming. In order for that to be effective, it would need to be electrically connected to the shield of the cable AND be protected from the sea water contact. Difficult to implement and ugly-looking.😢 If you do not mind the consequences of the electrolysis on a metallic connector, you could use one to replace the plastic-based but Quid of the Warranty?

This design was a result of the initial requirement of battery packs (then large capacity Lion type) to be exchangeable and to be able to have a double length (and capacity) battery pack option with an added possibility to carry it hip-mount with a longer battery cable. This is the preferred configuration of Le Jag. True, this power cable and connectors sticking out at the back are not looking nice and are sensitive to shocks. I think it is essentially due to the long stress reliefs added later on to the two connectors. These connectors have shown their limits in multiple mating/unmating and in their IP specs in terms of water pressure resistance Another type of over-molded power cable with different types of connectors is now being thoroughly studied and tested. This will probably enable the depth specs of the Impulse AQ LTD to be increased to a market-standard values. If the tests are finally successful, this cable will be shipped with the next orders of LTD and probably will be shipped by FTP to the existing users.

Only a few mills more in diameter. The battery compartment is an alu tube enclosed inside a shaft extension and protected from the contact with sea water in order to avoid any electrolysis effect between metals of different natures. The slight difference in diameter has required a new arm rest design (and tooling).

Yes, you can do that to solve this problem but you then generate a sensitivity to external EMI for the whole system.

The high voltage and short pulse delay of the Impulse are requiring a strict shielding of all the parts subjected to the pulses (coil, cable and connector). That effect is due to the small gap of continuity of the cable shield between the the male and female connectors and the changes of capacitance coming from the conductive water level variations. It was for that reason that the coil connector was initially made of metal in order to keep the continuity of the cable shielding up to the inside of the enclosure. (Same supplier, other item) Field tests in the sea water had shown a bad electrolysis effect on its body giving it a nasty look. A plastic connector had to be used for the AQ. The GOLD version will even require more attention to this capacitance effect as it will have a much shorter pulse delay, it will get an (expensive) stainless steel connector to keep a perfect shielding.

Designing a new mechanical system is a 'bit' more than tweaking a picture with Photoshop. This indeed looks nice BUT one also has to care about a lot of 'small' details like the costs and complexity of the tools to mold these plastic components and the way to assemble them to be sturdy and waterproof while keeping a light weight.

You would never be able to discriminate out BRONZE nails. You will have to live with them!!

Joe, Do not take any attention to the nasty remarks. Some people would never be happy with anything you could ever do. That is also the experience of Alexandre when making video. We are ALL very thankful about your many tests, very well documented, convincing and with clear audio. You are doing it like a pro. I suggest you just to follow your own learning curve and not react with video coming from endless forum requests. If you make video of your own tests, it's already very informative for everyone. Also, do not take too much time on that. Go detecting as Steve is doing. If it happens that you find GOLD on the way and there is a video showing it, it is the best convincing proof that the AQ is working well and that you strat mastering it.