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XP deus coil modification

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  • Hi Henrik, Have you seen this video on You Tube? It shows a way of quickly altering the frequency of the coil so as to cut out EMI http://youtu.be/dmIcE_CHBt4

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    • You mentioned the machine was playing a partial Iron tone for your target - this should likely be a phasing thing? you could try a 1nF across the Rx plug connection to throw the phasing a little and retest. Or across the Tx - like a fine tune and retest

      A lot of designs do not let any graphite to touch the ground - as you get a discharge and current flow and voltage changes on your coil - can false ..

      Could try this with a plastic bag taped over coil to simulate having no graphite on your surface.


      I think your coil may need this and you may do it with a coil cover! Don may make you a mirror part!!

      Beyond this, you may be looking at the limitations of your cable - I am unclear on the suitability of you cable.


      Anyway - you took on a huge challenge/risk/ investment and its looking good.



      I really think you have done an ace job here, in record time.

      I feel you are teaching us now. We never used to have a drain above and below and we never had sheild resistance this low, and we all suffer chatter on wet grass - so we need to try some of your work out.

      I cannot fault your enthusiasm and dedication to you project - Steve

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      • It is a 15nF capacitor that is being used in the resonant circuit of the transmitting coil. (In the You Tube video mentioned above)

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        • Muddy. He will properly lose some performance. Dont know but 15 NF is a Big one.
          Gulfnut - could Be a problem I hadn't notice, if the Graphite touch to the grass. Thanks.

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          • Hi all...
            Couldn't dare to go out with the 7" at one of my hot spot... What a nice day. The 7" coil allmust worked perfect.
            There is still some small breaks up in the signals, not much and some are from reel iron, and some from the coil mixing the ground effect with the good signal. But 95% perfect I would say.
            The best of all, I found a small hammered cobber coin from 1422, second signal with the 7" coil.
            The first good signal I got, was recorded. It was One thinny little piece af a bronze ring. (I wonder how small Gold this coil can find?)
            This is the Utube; http://www.youtube.com/watch?v=Vk7Dg-OcnGc&sns=em

            This is the video where I found the little cobbercoin, think 3-4" down.. Not bad. Made my day.
            http://www.youtube.com/watch?v=2u6q3ukh7fs&sns=em

            I did a test Shortly after the coin was found, to find out how it would compair with the 9" coil. Not bad either.
            This is the utube. http://www.youtube.com/watch?v=gXc4bBDbY5M&sns=em

            Then I made a test with a iron nail ( the field is filled with those kind ). This test allso gave the 7" coil a winner role, but but
            not by much. This is the utube. http://www.youtube.com/watch?v=hA-ieB3VoEY&sns=em


            Dear Friends. Without your help, this project couldn't had Be made. One Million THANKS.
            Now the finish paint and make it nice and usefull, then maybee the last try with 1.0 nf capacity, with a hope some small extra clearness can Be found in the signals... We did it, a new World record, 7" Deus coil in 3-4 weeks.
            Henrik.

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            • Sounds like a good result, Henrik. I'll watch the videos tomorrow.
              Are you going to try a proper small coil, like 5 inches?
              I still think there is some gain changes worth trying on the circuit-board. With this PCB being designed for a large coil, it possibly has a lower amplifier gain to match.

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              • Skippy I will look after a secondhand 9" coil and use this to the next project like a 5-6" coil.... This Bigfoot costed 120 £ and Maybee a 9" can Be found at the same prize.. That would allso give me the chance to test this 7" coil with the 9" PCB, plus find out how the 9" is made...
                Henrik

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                • But...but.. you have a plug and socket on this circuit board, so you can make as many different coils as you like? Like another small one, or a REALLY BIGFOOT, or a Two-Box set-up. (That's one of my projects for my F75, a two-box.)

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                  • Yes yes Skippy... But this issue that the PCB thinks its a Big coil, still is a open quenstretion.

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                    • Yes, but don't forget, almost every other machine out there has no idea what size coil is stuck on it, and they don't misbehave as a result. The most likely thing that is different between the different coils is the gain of the amplifier - lower for a big coil, higher for a smaller one, at a guess.

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                      • We still dont know why XP used different Freq. at all 3 Stock coils... 17.6 / 17.4 / 17.2 khz and lowest the Big coil, highest the 9" and the 11" in between. It could be something they had done in programming the brain at the PCB, which could Be ground coverage, or what it calls, when a bigger coil see more ground!!!

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                        • Maybe it's to do with interference between coils? Using two identical machines near each other is a bad idea, that's one reason many micro-based machines have freq shift eg. Tek T2, so two people can operate near each other. If you have two Deus coils, you can run them independantly, can you not, one on headphones, one on the controller+wired headphones?

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                          • You got it...Thats must Be why.

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                            • well done, i said before once you have a working bluetooth box winding other coils is trivial as you can reuse it on your other wound coils, the only limits are materials used, so 5",6",7" or whatever you like.
                              a nine inch coil board may work better on the 7" coil but who knows for sure, as skippy said it may well be the gain that is different, the only limiting factor is the cost of the deus coils, even more so just to chop them up, and of course damaged/cheaper deus coils are not worth risking for your purposes as you need to unsure correct function to start with.

                              one thought i had was maybe its possible to open the coils without destroying them, take out the board and battery and add a cable and reseal the coil, then connect it like one of yours, that way you will still have a working deus 9" coil, i doubt that its construction is different apart from size, you know how its done why completely destroy another coil there has to be a trade off where you can have your cake and eat it.

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                              • You need to make a really good multi-frequency 9 /10 inch coil winding. Then you can sell your existing stock coil. A future idea, maybe.

                                Regarding your RX coil pre-amp. Here is the circuit diagram. To increase the gain, your two obvious choices are (1) decrease R1; (2) Increase R2. You have to keep the time constants R1*C1, and R2*C2 the SAME. So one obvious solution is to halve R1 (add another R in parallel with it) and double C1 (another one on top of it). R1 is likely to be 47 - 100 Ohms, C1 probably 470nF. R2 is going to be 10 - 50 times larger, I should think. Doubling gain will give +14% air-depth, roughly. With your null not being super, any more gain may possibly cause problems.
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