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  • #46
    Originally posted by galal View Post
    thank you guys a lot,but before to read everything related to the inductance in that link that jerry typed it;take a look on the coil below,also this shape of coil existent in that link too,pls can you give an equation for inductance for this coil,i can't measure it with a device because it's expensive and i don't have a money, i spent my money on parts of TGSL,and don't know anyone have it,so i want to calculate it mathematically.can you help me
    The coil calculator is designed for round coils. To get an "approximate" inductance value for the D-shape coil, add the long and short diameters together and divide by two. Also, remember that the calculator uses the radius, and not the diameter.

    If you follow the instructions in the supplied link, you can build a coil without having to know the inductance value.

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    • #47
      thanks,i asked this because i made the coil 9",and the best thing to calculate the inductance to D coil that to transform it to circular coil,and when i calculate its inductance i see that for 9" coil should have approx 107 for TX and 111 for RX,anyway thank you

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      • #48
        One little tip that I use: Build your oscillator circuit first and then wind a few extra turns on your coil and then connect it to the oscillator and see what the frequency is. If your caps are right value, and the frequency is right, the inductance must be also. I have a TGSL oscillator and 4024 divider and the minus power supply built on it's own board and use that for testing purposes a lot. Also Satdaveuk posted a universal oscillator project here a while ago.

        Hope this helps

        Jerry

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        • #49
          thanks jerry,i have finished form built the board and the coil ,now i want to check the board and make sure that i don't have any mistake,really it's take a 3 weeks to build it,i will come back soon when i check it.

          thank

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          • #50
            Originally posted by galal View Post
            thanks jerry,i have finished form built the board and the coil ,now i want to check the board and make sure that i don't have any mistake,really it's take a 3 weeks to build it,i will come back soon when i check it.

            thank
            It took me a lot longer than that to build my first one but I lot to tinker a lot
            I am working on a EDU version of TGSL at the moment and I thought that it would be a snap. However last night I had to get back to basics and go over the entire board with a magnifier looking for breaks in the copper traces. That was something that I should have done before I started mounting the parts, but got over confident. I found several breaks that could not be seen with the naked eye so now perhaps my testing will make more sense than it has so far.

            Hope to have it finished in a couple of days.

            Jerry

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            • #51
              jerry,i have checked everything,but when i turn on it i don't hear any voice,voltage on 4024 pin 14 is 8v and converter it to -3v not -5v that's normal?,but why there's no voice,what the voltage on pin C TR3 should be?

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              • #52
                Originally posted by galal View Post
                jerry,i have checked everything,but when i turn on it i don't hear any voice,voltage on 4024 pin 14 is 8v and converter it to -3v not -5v that's normal?,but why there's no voice,what the voltage on pin C TR3 should be?

                No that is not normal. I get slightly over -6v on the negative supply. Something is drawing too much current and pulling the negative supply down a bit. Try reducing the load by removing the active devices. Also feel the audio transistors and see if they are warm.

                While there are many things that can cause not getting audio through the speaker, you should at least get a short beep when you first apply power or turn it off.

                Work on getting the minus supply where it should be and go from there.

                Jerry

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                • #53
                  ok,step step,now what i should to do to fix -3v to be approx -5v?

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                  • #54
                    Like I said in the previous post, remove things that connected to the minus supply. All of the IC's not related to the Oscillator or minus supply. What we are trying to determine at this point is if the problem is in the minus supply or if the the supply is OK and there is too much current draw that is causing the voltage to drop.

                    When everything is removed from the minus supply and the voltage is still at -3 volts then the problem is probably with tr7 & tr8 and associated components. In which case I would check that C4, C5 and D6, D7 are orientated correctly and that R9 and R10 actually do measure about 4.7k.

                    Since you are getting some but not full minus voltage, I suspect it is likely a loading problem.

                    One final thought, we were talking about coils earlier, have you made your coil yet?

                    Jerry

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                    • #55
                      hello ,
                      hello, I would like the scheme of a coil of 9" double-D for my TGSL. thank you

                      Annuler les modifications

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                      • #56
                        Originally posted by Jerry View Post
                        ...have you made your coil yet?
                        I'm about to start my IGSL in a few days and I thought of making a "work in progress" coil using a ferrite core. Actually several ferrite toroid cores because calculations say I'd get slightly into a saturation zone, so I'd use 4 of them and a half of turns instead. Seem handy enough.

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                        • #57
                          but before i do anything,i forgot to till you that,first i had checked the voltage by the avometer, in this moment i don't have an scope.second thing and this's important that i get -3v when the coil was connected and when i removed it i rechecked -5v part it was 0v,i mean no -5v when the coil is disconnect,i think the problem is 4024 IC,mybe it's not work,whats volt should be between the ground and pin 12 4024? when i checked it it's given 0v.

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                          • #58
                            Originally posted by galal View Post
                            but before i do anything,i forgot to till you that,first i had checked the voltage by the avometer, in this moment i don't have an scope.second thing and this's important that i get -3v when the coil was connected and when i removed it i rechecked -5v part it was 0v,i mean no -5v when the coil is disconnect,i think the problem is 4024 IC,mybe it's not work,whats volt should be between the ground and pin 12 4024? when i checked it it's given 0v.
                            Without coil you not supposed to get any negative voltage; so that part is ok.
                            And 4024 seems is also ok.
                            Without coil you get no oscillations, no freq. at 4024 input (pin1) and therefore no freq. at 4024 output (12.pin).
                            Reason why you get -3V with coil attached can be as somebody suggested: more drain at minus rail due some bad component or some short on pcb.
                            Connect coil and than measure freq. on pin 1 and 12 at 4024.

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                            • #59
                              It could also be a bad capacitor or wrong polarisation. Electrolytic are misbehaving if polarisation is wrong. See about the 220 micro in series with the transistors' collectors.

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                              • #60
                                Hi guys
                                sorry for delay,i have been looking about an oscilloscope when i get one i have measured the frequency,but before this i forgot something that i have checked the pcb it's don't have any short and the resistors R9,R10 is 4.3K not 4.7k damn the seller,and with respect to the frequency this is the result:

                                1) pin1 4024 equal 14.7khz

                                2) pin12 4024 equal 7.14khz

                                3) TX and RX freq and the phase shift between them
                                Attached Files

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