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  • TGSL Finished

    Hi everyone
    Sorry I not been on here for a while, business has been hectic to say the least, so not had chance to do much.
    Anyway my TGSL is finished far as construction, made case out of 2/8th styren made a few coils with my newly made electric coil mill with all the frills. Its been a good learning curve for me making these coils compared to the ones Ive made in the past for other machines, because although the 98/107 turns works for some of you it didnt for me, the TX coil no problems hit the 6.5MH everytime, Total opposit with the RX in fact I started doubting my inductance meter.Anyways with my set up Ive found 95/100 turnes TX/RX works fine giving 6.5MH/6MH at 23.5/24.35 ohms and I can churn them out fairly consistent by winding tight via a tention adjuster I installed on the feeder drum very easy to do as you will see in the pictures I will post later.
    Carefully taking the upper drum cover off small tempory cable ties to keep wire together, check induction/impeadence, spot glue, let dry, check inductance again, cut ties, lume as most of you do, check induction again, then glue all over/leave till following day.
    Now what I found is at this point with a little messing about get my 6/6.5mh quite easily, or should I say my meter says so.
    I did as advised on here checked TX frequency with both my frequency counters to be sure , hooked up the RX coil onto the TX circuit, all well within range almost spot on as the spec says.
    Far as making the PCB it was done like Ive done it for many years very simple just printing from a laser printer then hot iron onto the copper clad, easy peazy if you use good quality PCB , fiber glass based with a good gauge layer of copper, use the cheap blown carboard then you get a half shot PCB with the copper floating, all learnt the hard way from previous experience may I add.
    Now after all said and done, turned the machine on and it comes out with a lovely tone nice to the ears, but thats all, soon as I overlap the coils it goes silent but no matter what position I put them in it doest hardley detect metal so now im going to be forced into fault finding which is proberly a good thing in the long run to learn how it ticks.
    Any guides to my problem will be greatfully received, in return anyone want to know any of my tips on pcb making or my coils tricks please feel free to ask.

    Warm regards

    Dave

  • #2
    Originally posted by satdaveuk View Post
    Hi everyone
    Sorry I not been on here for a while, business has been hectic to say the least, so not had chance to do much.
    Anyway my TGSL is finished far as construction, made case out of 2/8th styren made a few coils with my newly made electric coil mill with all the frills. Its been a good learning curve for me making these coils compared to the ones Ive made in the past for other machines, because although the 98/107 turns works for some of you it didnt for me, the TX coil no problems hit the 6.5MH everytime, Total opposit with the RX in fact I started doubting my inductance meter.Anyways with my set up Ive found 95/100 turnes TX/RX works fine giving 6.5MH/6MH at 23.5/24.35 ohms and I can churn them out fairly consistent by winding tight via a tention adjuster I installed on the feeder drum very easy to do as you will see in the pictures I will post later.
    Carefully taking the upper drum cover off small tempory cable ties to keep wire together, check induction/impeadence, spot glue, let dry, check inductance again, cut ties, lume as most of you do, check induction again, then glue all over/leave till following day.
    Now what I found is at this point with a little messing about get my 6/6.5mh quite easily, or should I say my meter says so.
    I did as advised on here checked TX frequency with both my frequency counters to be sure , hooked up the RX coil onto the TX circuit, all well within range almost spot on as the spec says.
    Far as making the PCB it was done like Ive done it for many years very simple just printing from a laser printer then hot iron onto the copper clad, easy peazy if you use good quality PCB , fiber glass based with a good gauge layer of copper, use the cheap blown carboard then you get a half shot PCB with the copper floating, all learnt the hard way from previous experience may I add.
    Now after all said and done, turned the machine on and it comes out with a lovely tone nice to the ears, but thats all, soon as I overlap the coils it goes silent but no matter what position I put them in it doest hardley detect metal so now im going to be forced into fault finding which is proberly a good thing in the long run to learn how it ticks.
    Any guides to my problem will be greatfully received, in return anyone want to know any of my tips on pcb making or my coils tricks please feel free to ask.

    Warm regards

    Dave
    Dave,
    Yes! 5 turns difference between Rx and Tx is the answer I come up with every time with many coils. Even coil calculators show 5 turns difference. If I do the 98/107 combination I cannot get correct phasing. I can even vary the number of turns a little, but if I keep a difference of 5 turns the phasing is still correct even though the inductances are off. I am almost finished with a 9" coil and guess what.. 5 turns difference! 106/111 turns needed for correct inductances.

    C1, C2 and C6 come into play as well as how sheilding is done but if I measure the caps and pick the values closely I still need 5 turns difference.

    Don

    Comment


    • #3
      Same for me - I came to it when I messured L before and after removing one turn. On turn was 0.1mH....

      Comment


      • #4
        Originally posted by satdaveuk View Post
        Hi everyone
        Sorry I not been on here for a while, business has been hectic to say the least, so not had chance to do much.
        Anyway my TGSL is finished far as construction, made case out of 2/8th styren made a few coils with my newly made electric coil mill with all the frills. Its been a good learning curve for me making these coils compared to the ones Ive made in the past for other machines, because although the 98/107 turns works for some of you it didnt for me, the TX coil no problems hit the 6.5MH everytime, Total opposit with the RX in fact I started doubting my inductance meter.Anyways with my set up Ive found 95/100 turnes TX/RX works fine giving 6.5MH/6MH at 23.5/24.35 ohms and I can churn them out fairly consistent by winding tight via a tention adjuster I installed on the feeder drum very easy to do as you will see in the pictures I will post later.
        Carefully taking the upper drum cover off small tempory cable ties to keep wire together, check induction/impeadence, spot glue, let dry, check inductance again, cut ties, lume as most of you do, check induction again, then glue all over/leave till following day.
        Now what I found is at this point with a little messing about get my 6/6.5mh quite easily, or should I say my meter says so.
        I did as advised on here checked TX frequency with both my frequency counters to be sure , hooked up the RX coil onto the TX circuit, all well within range almost spot on as the spec says.
        Far as making the PCB it was done like Ive done it for many years very simple just printing from a laser printer then hot iron onto the copper clad, easy peazy if you use good quality PCB , fiber glass based with a good gauge layer of copper, use the cheap blown carboard then you get a half shot PCB with the copper floating, all learnt the hard way from previous experience may I add.
        Now after all said and done, turned the machine on and it comes out with a lovely tone nice to the ears, but thats all, soon as I overlap the coils it goes silent but no matter what position I put them in it doest hardley detect metal so now im going to be forced into fault finding which is proberly a good thing in the long run to learn how it ticks.
        Any guides to my problem will be greatfully received, in return anyone want to know any of my tips on pcb making or my coils tricks please feel free to ask.

        Warm regards

        Dave
        Dave, in regards to your problem. Do you have a dual trace scope? If so, look at post 4649 and download part# 1 of the PDF. Start on page 4:
        http://www.geotech1.com/forums/showt...960#post128960

        Go though the test points indicated in red just for a comparison. It's beneficial to look at the phasing of everything, referencing the Tx signal.

        Don

        Comment


        • #5
          Thanks Don
          I worked through the night until work next day to finish this project, and as I previously stated it will do me good to do some good old fasioned fault finding, I checked the ovious ie supply lines, visual inspection of component placments, printed circuit etc, already found the RX tunning cap is well below tolerence coming in at 13.9nf, where it should be 15, thought that would be good place to start.
          All my components are as stated in avionics spec final.
          I will have a go at it after I got my daughter to bed, I got the scope and it does work, although most here would proberly laugh, its old as the hills back to when serving my time, I am 53 in august so you have a idea of the age lol.
          I need to get this project totaly finshed by august because i want to give it a pasteing on the beach in cornwall then pasture/plough land here where I live, its a tuff test for any detector, and has shown many a detectors weakness/failings wether branded or not, I shall not mention names.
          You have guessed it if you didnt already know, Location here in England, If they work ok here with all the iron within are soils, they will work better any where else in the world.
          Everyting from start to finish of this project I have logged with many pictures and technical data, incl my coil winder project which will be posted here at the very end for fucture reference incl field tests.
          When I get back I want to build the delta PI , unless you know of a better one on here.
          Warm regards as always
          And thanks to everyone who donated there time and knowledge on this project.

          Dave

          Comment


          • #6
            I just downloaded part one and two for reference great job, I looked at that ages ago, infact if you look I had commented on it but had forgot about it.
            Nice graphics Simon, wait to you see mine from the arc lol.
            Im pleased we cracked the coil issues, I knew we would do it, by hook or crook.
            All the best
            Dave

            Comment


            • #7
              pcb plus housing

              Hi
              Not installed the coil socket yet until im happy with the machine, makes life easer to take measurements etc, plus still waiting for the lm308s i think the last lot from hong kong were duff, but time will tell.
              Attached Files

              Comment


              • #8
                some coil pics

                Some good some not so good as most of you know it was very much a learning curve.
                On image 70 is when i started doubting my inductance meter, as you can see between high and low settings they are very much different.
                Attached Files

                Comment


                • #9
                  more coils etc

                  more pics, it was later i started to use bog standard kids paper glue on the wire leading into the drum, it sticks just enough to allow removal of top drum for spot glueing/lumming. not as good as varnish but no mess at all because where theres so much water content in the glue it just soaks into the wood, but just enough sticky to hold windings together.
                  Next time im going to try wall paper glue, it should work the same but a bit more sticky.
                  Attached Files

                  Comment

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