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  • #16
    Here is a peep at the TX board and the UNIPI board. I think we could make a single board with the PSU, the UNIPI and the TX board.

    The 4 Mosfets must be tied to the same heat-sink. As it is, it gets barely warm.

    Tinkerer
    Attached Files

    Comment


    • #17
      yes i agree, and if some want something a lttle different im sure it will be able to be adapted in someway, and as you said earlier to someone on here this project will never be finished as in final which is what Geotech is all about.
      Maybe a good idea to use version numbers for those who get involved later on.
      Like your test setup tinker you have been busy.
      So now where do we go from here?

      Regards

      Comment


      • #18
        Originally posted by satdaveuk View Post
        yes i agree, and if some want something a lttle different im sure it will be able to be adapted in someway, and as you said earlier to someone on here this project will never be finished as in final which is what Geotech is all about.
        Maybe a good idea to use version numbers for those who get involved later on.
        Like your test setup tinker you have been busy.
        So now where do we go from here?

        Regards
        Maybe a good way to proceed, would be to tackle the project at the different block simultaneously.
        We could look at the different options, discuss and suggest and come to a consensus of the version we want to execute. This will depend more on yourself than on me, because we are designing the detector for your specific purpose, namely, to walk the fields in the UK.

        Things are very different here and I have to work with the parts at hand. It is very costly for me to get parts, so I buy only once or twice per year.

        So, when I suggest a way to do things, it is a guess from far away, from your angle things may look different.

        To get started:

        The coil is one of the most important parts. It would be good to get going on that. I have built quite a few coils and suggest a very specific coil for the project, based on my experience.
        This coil is slightly different from other coils I have built, with the intention of improving on it's predecessor that worked fine.
        If this is OK with you, I will send you exact dimensions and data tomorrow.

        Another part to get busy with, is the PSU. A good, efficient and noiseless powersupply can make all the difference. The PSU I used on the Tinkerers IB-PI_V1, way synchronized with the TX, but wasted 50% of the power.
        I prefer to apply the power on the TX instead of wasting it.
        Like all things electronic, new and better parts become available every day, but it is getting more and more difficult to find through hole parts.
        So, lets see what we can find in parts and design the PSU around that.

        Still another design block to look at, is the audio output. The UNIPI gives a clicking output. I like the clickers, it was my preferred audio, using a "bone conductor" for the underwater detector. However, on land, it is different. OK maybe with a headphone, but, how do we amplify a clicker so it can be heard a few feet away?

        These are some subjects for suggestions.

        I am all ears.

        Tinkerer

        Comment


        • #19
          Audo stage

          This is a good audio amp low current that can be cranked up to 2 watts into a 8 ohm speaker with a good frequency responce used in the Ivonics TGSL, not to be confused with earlier and later circuits its based round the common 1 off BD140 and 2 off BC157.
          This circuit as whole works better when using hand picked and tested components of the exact specification as listed like many projects ive built and tested, so where possible thats the way to go here for us to get optium performance.

          Regards
          Attached Files

          Comment


          • #20
            Using a jig

            I been thinking Tinkeror
            You mention starting modular approach, im all for that, infact ive done that many times in the past with different projects .
            So if we are going down that road which is a good idea what we need is a open jig, ie plinth with front and rear upright panels made as light as possible that finaly can have a cover fit over it to do various outside tests.
            The large one off heat sink can be mounted on one of the retaining panels or free standing depending on choice of design.
            My idea is make the jig as explained using styrene prepared with shielding which will be explain to all later, its so easy to cut and glue and of course once all built its easy to mount the top cover etc, you end up with a custom housing to suite requirements which is very cheap and light as a feather.
            So after saying that maybe the jig and power supply comes first.
            Have you any idea of dimentions that going to be required?

            Regards

            Comment


            • #21
              Originally posted by satdaveuk View Post
              I been thinking Tinkeror
              You mention starting modular approach, im all for that, infact ive done that many times in the past with different projects .
              So if we are going down that road which is a good idea what we need is a open jig, ie plinth with front and rear upright panels made as light as possible that finaly can have a cover fit over it to do various outside tests.
              The large one off heat sink can be mounted on one of the retaining panels or free standing depending on choice of design.
              My idea is make the jig as explained using styrene prepared with shielding which will be explain to all later, its so easy to cut and glue and of course once all built its easy to mount the top cover etc, you end up with a custom housing to suite requirements which is very cheap and light as a feather.
              So after saying that maybe the jig and power supply comes first.
              Have you any idea of dimentions that going to be required?

              Regards
              OK, let's see what we want on the front panel.

              ON - OFF switch
              Audio volume control pot.
              The LCD of the UNIPI
              The encoder push button of the UNIPI
              The other 2 push buttons of the UNIPI
              SAT control pot

              Rear panel

              Heat sinks. Actually we might make the rear panel THE heat sink.

              Cable outlets

              There are 3 cables, twisted, going to the TX coil, maybe we should shield them too.
              There are 3 cables, twisted and shielded, going to the RX coil.
              Bulkhead connectors? Cable connectors?

              Specific cables for each?

              The Battery
              We could simplify things for a start, using direct 12V battery output, unregulated. Of course, this means that the performance of the detector will vary as the battery voltage changes from full to low.
              It will also cut down the original goal of depth rating to about 30%.

              The battery could be a simple lead-gel cell. A bit heavy, but we need weight for counterbalancing the large coil.

              Tinkerer

              Comment


              • #22
                TINKERERS_TEM_IB-PI

                TX and Bucking Coil

                TX – 24 turns, CLOCKWISE, #14Awg, Audio cable, fine stranded. Wind 4 turns wide and 6 turns high
                Inner dimension for winding 95cm x 45cm
                Bucking coil wound with the same cable, ANTICLOCKWISE, 6 turns in line high, single layer.
                Inner dimension for winding 70cm x 30cm
                Total cable needed, about 87 meters, about 1.4Kg.

                TX voltage and cable gauge.

                The choice of the TX voltage

                At TX 190us, about 5000 PPS, Pulses Per Second
                At 30V, AWG #14, cable we get about 5.2Amps peak coil current. 1300gr copper, 4.2 Watt
                At 12.5V we get 2.17A
                At 11V we get 1.91A
                With 12.5V and AWG #16 cable, we get 2.13A. 822gr copper, 750mWatt
                With 12.5V and AWG #18 cable, we get 2A. 460gr copper, 1.2Watt
                But this is not all. The increased resistance also reduces the efficiency. More losses, compare the Watt power consumption.

                Tinkerer

                Comment


                • #23
                  Great stuff Guys,
                  You're a powerhouse Tinkerer, the ideas just keep on flowing, magnifique!
                  To get involved in this project should I build a UNI PI and TEM TX? I'm pretty blank on the ideas front but would like to contribute something towards it.

                  My quarry is deep largish nuggets, they would not be dissimilar to old coinage and bronze age artifacts, so perhaps this would be a multipurpose machine, no?

                  I've long wanted to do a modular design with the motherboard having the power supplies and the other blocks, Tx, Rx, uC, Audio etc., being pluggable modules into the MB. Then various upgrades and experiments can be done on any one block without scrapping the whole board and starting from scratch, much like what you're doing now Tinkerer.

                  I though need to do a compact version for high mobility, surface mount etc., which has always been a bit of a pain for me since when down scaling circuits I've found many problems arise when placing components close together....it requires much skill I believe to do really good compact layout on mixed analogue/digital solutions.

                  Cheers
                  Kev.
                  Last edited by Kev; 04-24-2012, 01:16 AM. Reason: non-sense

                  Comment


                  • #24
                    Originally posted by Kev View Post
                    Great stuff Guys,
                    You're a powerhouse Tinkerer, the ideas just keep on flowing, magnifique!
                    To get involved in this project should I build a UNI PI and TEM TX? I'm pretty blank on the ideas front but would like to contribute something towards it.

                    My quarry is deep largish nuggets, they would not be dissimilar to old coinage and bronze age artifacts, so perhaps this would be a multipurpose machine, no?

                    I've long wanted to do a modular design with the motherboard having the power supplies and the other blocks, Tx, Rx, uC, Audio etc., being pluggable modules into the MB. Then various upgrades and experiments can be done on any one block without scrapping the whole board and starting from scratch, much like what you're doing now Tinkerer.

                    I though need to do a compact version for high mobility, surface mount etc., which has always been a bit of a pain for me since when down scaling circuits I've found many problems arise when placing components close together....it requires much skill I believe to do really good compact layout on mixed analogue/digital solutions.

                    Cheers
                    Kev.
                    Hi Kev,

                    the mother board idea keeps coming up from time to time. It has a lot of merit, but on closer look, the individual needs are often so different that it is really difficult to design a detector to fit all needs. Unless one makes so many compromises that the final result becomes a very watered down "super lite" model.

                    The basic idea for the TINKERERS_TEM_IB-PI, is for a detector to walk the open fields. Is this where you are going to look for nuggets?

                    If you go through all the trouble to build your own detector, I am sure you want it to be as close as you can get, to your individual needs.

                    What are these needs? If you give me some hints, I can come up with ideas of meeting these needs.

                    Does it rain a lot where your nuggets are? A water proof detector might be the answer. This means few controls.

                    Are you detecting in the woods? The ergonomics of large coils become problematic. How deep do you want to detect? The depth is relative to the coil diameter.

                    Can we find solutions to all your needs? Well, we can give it a try.

                    Tinkerer

                    Comment


                    • #25
                      TINKERERS_TEM_TX_LP

                      Here is another little piece of the detector. A LP (for low power) TX board.

                      As I showed above, there is quite a difference in power between 12V and 30V TX. So this is the low power TX, running on 12V. Still capable of reaching very deep.

                      Enjoy

                      Tinkerer
                      Attached Files

                      Comment


                      • #26
                        Hi Tinkerer,
                        Sorry for the delay in replying, I had to nip away for a week.
                        I don't want to hijack this design I just realised that if you were tailoring it towards old coinage and artifacts as per satdaveuk's suggestion, then I could adapt it for my needs.

                        The type of country I hunt, is somewhat like Northwest European Roman sites, having lots of tussock grasses and peat that reduce depth markedly. I'll link to some photos when flickr stops having hiccups.

                        I expect I would need a coil size of around 60 cms able to detect a 10 gram nugget (20mm coin) at about 45 cms. The Minelab GPX4500 will easily detect such a target at 40 cms and deeper with a 45 cm coil. The problem with the Minelab is its weight and poor ergonomics. Hence my original thoughts of miniaturizing Tinkerer's PI (SMD, 4-6 layer PCB) as many of my sites are many miles from roads well away in the mountains, and I need to lug enough power for up to 40 hours detecting. A flexible roll-up solar panel is an option in summer, but not in spring or autumn.

                        Showerproof would be ideal as mountain weather is unpredictable, however the possibility of a waterproof fresh water discriminating machine could open up vast areas.

                        As previous posters have said on this thread, you have already developed a detector already that has such potential, it exists across many posts and threads in the form of developmental blocks. The problem is deciding which blocks to collect and assemble to get a working optimised machine. I think the Guys, myself included were very interested in your assembling such blocks in one thread as a complete design. However, the potential of a TEM solution could over shadow all your previous work, and so I don't want to discourage you from proceeding down this course instead.

                        I am interested in your 12V front-end, since I will need to go with a medium power option. I suspect that using the TEM system will actually produce results only achievable with much higher powered front-ends, do you agree?

                        Cheers
                        Kev.

                        Comment


                        • #27
                          The TEM-TX board the GG Group are working on with Tinkerer will have three switchable power levels and I hope to be making the new prototype boards in the next couple of weeks and Tony I have built three different audio stages for testing including the one suggested by satdaveuk.

                          Regards, Ian.

                          Comment


                          • #28
                            Thats great
                            I didnt bother you both for the last couple of days because gathered you would both be busy working on the project, if theres anything you think I could help just ask, although my technical ability with this design is limited always willing to try and learn.

                            Warm regards

                            Comment


                            • #29
                              Actually im going to be applying that sound output stage to the mini pulse 3 project, main pcb is full populated will make another small pcb for the audio, bit over the top but can always turn the volume down

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                              • #30
                                That is what I did just built it onto a small bit of D/Sided board as a plug in so we can test various designs have fun.

                                Regards, Ian.

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