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  • Originally posted by Carl-NC View Post
    The stainless hypodermic needle is probably a good test if you want to design a serious minimum-metal mine detector. If you want a consumer-grade WWII mine detector then it's probably way overkill.

    I have both a Garrett and a Minelab mine detector. I'm told that the Garrett is a modified Infinium circuit. It came with a s/s firing pin test target embedded in a 5" long stick, and the Garrett just picks it up (in air) at the length of the stick. The TDI falls short by 1/2", so even as a minimum metal mine detector the TDI design is pretty close.
    Carl, have you ever tested some old models from your collection like BFOs and others oldtimers design, on small stainless parts sensitivity?

    Comment


    • Originally posted by WM6 View Post
      Infinium do not suit well as tiny nuggets detector.

      My 1,1gram testing gold nugget it can detect in air at 8cm (in comparison: AT Gold can detect it at 12cm, the same my Tesoro Diablo II).

      1.1gram gold pendant (round, diameter 15mm) it can detect (at twice the distance of 1.1gr nugget) - at 16cm.

      At distance of 20cm you mentioned it can detect in air 20gram titanium (6Al-4V) test target (screw).

      As I say, stainless hypodermic needle it cannot detect at all.
      Enough, enough of the damn hypodermic needles. I took out a disposable one and when I wanted to pull off the plastic cover of the needle to measure it, it was kind of stuck, then suddenly it came loose and my hand jerked and the needle went right through my thumb. In one side and out the other side. These things are really sharp. I can see some sense in wanting to collect them from the school grounds.

      Anyway the needle is a #21x1.5". It was written on the plastic envelope. It is easy to detect at a good distance.
      The morale of the story, if we talk about the needles as test targets, we must add the dimensions. They come in many sizes.

      Tinkerer
      Last edited by Tinkerer; 07-12-2012, 10:22 PM. Reason: typos

      Comment


      • Originally posted by WM6 View Post
        Infinium do not suit well as tiny nuggets detector.

        My 1,1gram testing gold nugget it can detect in air at 8cm (in comparison: AT Gold can detect it at 12cm, the same my Tesoro Diablo II).

        1.1gram gold pendant (round, diameter 15mm) it can detect (at twice the distance of 1.1gr nugget) - at 16cm.

        At distance of 20cm you mentioned it can detect in air 20gram titanium (6Al-4V) test target (screw).

        As I say, stainless hypodermic needle it cannot detect at all.
        Could you give us an estimate of the face surface area of the nugget? Would it be maybe 1/3 of the surface area of the pendant?
        Most detectors respond mainly to the surface area of the target, but some time ago I made a test series with a few targets of the same surface, but different thickness and the response seemed to be about proportional to the thickness.

        Can anybody add some more information about "thickness response"?

        Tinkerer

        Comment


        • Originally posted by Tinkerer View Post

          The morale of the story, if e talk about the needles as test targets, we must add the dimensions. They come in many sizes.

          Tinkerer
          I tested different sizes from 25mm to 50mm in different thickness all without any success.

          At first I believe that AT Gold can detect small stainless needle, but after some check I found that AT Gold can be set so sensitive, that it can detect my hand. Then I put needle on plastic ruler and - detecting disappear.

          BTW: smaller sewing needle can be detected easily, but not stainless hypodermic needle.

          Comment


          • Originally posted by sawmill View Post
            Tinkerer

            Yes open spokes will grab ,weeds ,brush,and rocks,plus they are
            not as durable as a solid coil.

            I like the 24 volt idea just fine,as a matter of fact I would rather
            have 24 volts.

            OK on those needles, a GMT,GM3 Whites,or a Gold Bug 2, will find
            them easy. Also a Garrett Recon Pro ,or a Minelab F3 mine detector
            would get them too,and at depth. You can buy both mine detectors
            as military surplus with the complete kit including chargers pretty cheap.
            Have you tried a mine detector as a nugget detector?

            Tinkerer

            Comment


            • Originally posted by WM6 View Post
              I tested different sizes from 25mm to 50mm in different thickness all without any success.

              At first I believe that AT Gold can detect small stainless needle, but after some check I found that AT Gold can be set so sensitive, that it can detect my hand. Then I put needle on plastic ruler and - detecting disappear.

              BTW: smaller sewing needle can be detected easily, but not stainless hypodermic needle.
              Yes, it is a common mistake to hold the target in the hand. Even if the hand does not seem to be detected, it may bring the signal close to the threshold and then any little bit will trigger the response. A plastic ruler that is longer than the diameter of the coil is good.

              I am surprised that you can not detect the needles, while Sawmill and Carl, can. Different alloy?

              Just now, I tested my bloody needle with an 18" coil and have no problem at all.

              Tinkerer

              Comment


              • Originally posted by Tinkerer View Post

                I am surprised that you can not detect the needles, while Sawmill and Carl, can. Different alloy?

                Just now, I tested my bloody needle with an 18" coil and have no problem at all.
                Where did you find Carls claim on his needle detecting?

                You can detect stainless needle with 18" coil in sweet dream only or you have needle like this one:
                Attached Files

                Comment


                • Tinkerer

                  No I haven't used a mine detector for gold,but I don't see any
                  reason that the Minelab F3 couldn't be a good prospecting ,or relic
                  machine . I would sure like to try one. The Garret Recon is not as
                  sensitive but it would probably work plenty good too. Just google
                  Minelab F3, and it will make for some interesting reading.

                  I am trying not to bash or start any detector wars. Personally I
                  use several brands of detectors. None is perfect,but each one has
                  something that another may lack. My favorite prospecting machines
                  are the GM3 Whites,and the TDI SL, but that is just me. I also have
                  a good SD 2200D ,that does a fine job too. Detectors are just tools,
                  and the key is to pick the best tool for the job at hand. I have never
                  owned a detector that didn't find gold.

                  Comment


                  • Originally posted by sawmill View Post
                    Tinkerer

                    No I haven't used a mine detector for gold,but I don't see any
                    reason that the Minelab F3 couldn't be a good prospecting ,or relic
                    machine . I would sure like to try one. The Garret Recon is not as
                    sensitive but it would probably work plenty good too. Just google
                    Minelab F3, and it will make for some interesting reading.

                    I am trying not to bash or start any detector wars. Personally I
                    use several brands of detectors. None is perfect,but each one has
                    something that another may lack.
                    My favorite prospecting machines
                    are the GM3 Whites,and the TDI SL, but that is just me. I also have
                    a good SD 2200D ,that does a fine job too. Detectors are just tools,
                    and the key is to pick the best tool for the job at hand. I have never
                    owned a detector that didn't find gold.
                    Well said!
                    That's why we do change them from time to time and not stuck with only one for a lifetime.
                    Local soils and conditions do define md model (at smart users).
                    I have changed approx. 90 models so far. Each one of those i liked and still do like.
                    But i had to sell one - to by another. Bad luck, because i can not afford to keep them all for good in my collection.

                    Comment


                    • Originally posted by Tinkerer View Post
                      What is the weight of the titanium screw? Size in mm?

                      Are these different settings on the DEUS?

                      Tinkerer
                      Screw data:

                      Titanium Alloy 6Al-4V, M5x10mm, weight 1.1gram.

                      Comment


                      • Originally posted by sawmill View Post

                        OK on those needles, a GMT,GM3 Whites,or a Gold Bug 2, will find
                        them easy. Also a Garrett Recon Pro ,or a Minelab F3 mine detector
                        would get them too,and at depth.

                        .
                        Sawmill those stainless needle cannot be detected in direct touch by one of the best pin-pointer (Pro-pointer) available too.

                        So you can forget on GMT, GM3, GB2 etc.

                        If you are detected something like hypodermic needle using mentioned devices in real and not only imaginative, then:

                        - or your needle wasn't out of stainless steel (did you check it by magnet?),
                        - or you detect your own "testing" hand (possibly with wristwatch and ring on it),
                        - or those needles was "something" plated.

                        Comment


                        • Originally posted by WM6 View Post
                          Where did you find Carls claim on his needle detecting?

                          You can detect stainless needle with 18" coil in sweet dream only or you have needle like this one:
                          Did I sin against Carl's 7 commandments?

                          1. KEEP YER TRAP SHUT. Unless the project is a public effort, as many are here on Geotech. While premature public hyping doesn't necessarily break a project, it does incredible damage to the reputations of the design and the designer when things don't work out, as is the case 95% of the time.

                          "Unless the project is a public effort" so I should be forgiven.

                          I am really not trying to brag. Up til now we have a very serious discussion, just trying to collect information. And we are getting very valid information from different parts of the world together.

                          Some of the claims do not seem to corroborate. It is worth looking closer to find the reason.

                          The disposable hypodermic needle in question is made in China. It is very slightly attracted to a strong magnet, like many stainless steel alloys are. I buy them by the 500 box because I use them for my lawnmower.

                          The 18" IB coil and circuit are just makeshift experimental. The RX circuit is the front end of a non-motion pulse induction design under development.

                          If you want to try to reproduce the performance, I will gladly supply you with the schematics of the TX and RX circuit as well as the HEX file of the PIC, but only if I have your firm promise that you will sincerely build it and honestly test it.

                          Most of my experimental circuits are already posted on the forum as OPEN SOURCE.

                          Hrmmm, back to the subject. We need to be more precise with the information. For example, the needle is presented flat to the coil, not vertical. Air test of course.

                          Tinkerer

                          Comment


                          • Originally posted by sawmill View Post
                            Tinkerer

                            No I haven't used a mine detector for gold,but I don't see any
                            reason that the Minelab F3 couldn't be a good prospecting ,or relic
                            machine . I would sure like to try one. The Garret Recon is not as
                            sensitive but it would probably work plenty good too. Just google
                            Minelab F3, and it will make for some interesting reading.

                            I am trying not to bash or start any detector wars. Personally I
                            use several brands of detectors. None is perfect,but each one has
                            something that another may lack. My favorite prospecting machines
                            are the GM3 Whites,and the TDI SL, but that is just me. I also have
                            a good SD 2200D ,that does a fine job too. Detectors are just tools,
                            and the key is to pick the best tool for the job at hand. I have never
                            owned a detector that didn't find gold.
                            I just downloaded the F3 manual. Impressive!!!!

                            Let's talk a bit more about the metal detector as a tool.

                            One thing I learned from the discussion is that hobby detectors are toys. As such, the more gadgets and bells and whistles, the better they sell.

                            For serious work one wants a tool. Within the tools one might also find a gadget tool, like a hammer that is also a pliers and also a screwdriver and also a knife, but a serious professional knows that he wants to use a quality hammer only or a quality screwdriver only.
                            A seasoned professional likes to use quality tools.

                            A start-up professional may have to buy lower quality tools that he can afford. But one of the first things that experience teaches him, is that working with the right quality tools is more efficient.

                            Military mine detectors are highly specialized quality tools. Are there other quality professional metal detectors on the market?

                            There are industrial detectors for security. There are Tramp Metal detectors for conveyor belts. Each of these is very specific to it's use.

                            What else is there?

                            Tinkerer

                            Comment


                            • Minelab F3 mine detector on ebay, for US$900.


                              http://www.ebay.com/itm/ws/eBayISAPI...m=190700659813

                              Tinkerer

                              Comment


                              • WM6
                                Have you ever used a GM3? You may want to do a little research.
                                There is a reason that I do use one!

                                Comment

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