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  • the two OpAmps of U8 receive the sine wave from TX generator and convert to square wave for control 3 parts of quad bilateral switch U2.

    The mesh consisting of C23, R43 + VR3, and C24 cause some delay of the square wave for switching (U8 - pin 1) will respect to the other square signal existing in U8 - pin 7.

    VR3 are used to the fine adjust angle of this delay and thereby enable a RX signal sampling at different times to the first two low pass filters of U3.

    Comment


    • thanks for the info :-)

      Comment


      • Fisher 10.5 "1270 x Spider Series. 10.5" Spider Coil / CZ Series

        Fisher 10.5 "1270 x Spider Series. 10.5" Spider Coil / CZ Series
        Someone here knows if there is a difference between the two or are they the same?
        Because I have installed the first and there were no differences.

        thank you

        Comment


        • Calculating the resonant frequency of the LC circuit Tx (0.587uH - 1 uF) is the result of: 6569 kHz.
          Ok! Close to 6.6 kHz which is supposed to work the IDX Pro ...

          But the resonance circuit LX with LC with the values ​​that are indicated in the forum (35.6mH - 33nF) when calculated result in: 4.643 kHz. ???

          The TX frequency is very different from the frequency which is tuned to the element of RX. This in terms of common law power transmission is totally out of logic, it appeared that the values ​​indicated for LC Rx are not adequate for listening to the signals sent back by the target ...


          Some of the friends that understood more deeply in the technical operation of the MD's could clarify whether this is really an error, or if there is any special reason for this large difference of the two elements tuned?

          Comment


          • Originally posted by Sun_rise_pt View Post
            Calculating the resonant frequency of the LC circuit Tx (0.587uH - 1 uF) is the result of: 6569 kHz.
            Ok! Close to 6.6 kHz which is supposed to work the IDX Pro ...

            But the resonance circuit LX with LC with the values ​​that are indicated in the forum (35.6mH - 33nF) when calculated result in: 4.643 kHz. ???

            The TX frequency is very different from the frequency which is tuned to the element of RX. This in terms of common law power transmission is totally out of logic, it appeared that the values ​​indicated for LC Rx are not adequate for listening to the signals sent back by the target ...


            Some of the friends that understood more deeply in the technical operation of the MD's could clarify whether this is really an error, or if there is any special reason for this large difference of the two elements tuned?
            Good observation and you are correct. Almost all IB VLF detectors are that way. Basically, if you had a detector tuned to full resonance it would be a handful to keep tuned. I built the Volksturm and played with tuning a bit. Keeping the GB setting correct was like trying to balance it in the head of a pin! Off resonance makes adjustments much easier with very little loss of sensitivity. Others have described phase response as being "non linear" if tuned to full resonance. Knock yourself out! That's what experimenting is all about. Check out the discussion on the "Nexus"

            Don

            Comment


            • Originally posted by Schatztaucher View Post
              I suppose eduardo has made ​​the changes. The thing with the diode discussed in the Russian forum too. with an 8 ohm speaker, the MPSA13 burned again. Thursday I'll try it with a piezo speaker.
              silverdog idx works but also ..... but how?

              regards, marc
              My IDX is working. I bought BC517. It is good for machine. With the original W3900 coil make a 25 cm for gold ring. I must make a good coil or buy an other. :-(

              Comment


              • thank you all for your answers they helped me a lot
                I hope with your help I can improve the IDX,

                greetings

                Comment


                • In my personal experience, I think the resonance of the LC circuit of the reception is very important because in addition to conveniently filter all what you are receiving, reducing the window for optimal detection, ie: improving the Q (quality factor).


                  I take the liberty of reproducing the end of doc which refers to the importance of perfect resonance:

                  HTML Code:
                  http://www.nexusdetectors.com/sciencemetaldetectors.html


                  Nexus, a important name for the manufacturers of MD refer also the validity of this concept in a very interesting document and reading accessible even for non-technical people at:

                  "...The best metal detectors regarding depth penetration and discrimination accuracy are the IB detectors tuned in total or as close as possible to total electro-magnetic resonance.

                  The reasons:
                  It is not possible for any kind of loop to achieve higher Q than the Q as a result of electro-magnetic resonance.
                  In comparison to a standard, not tuned in resonance search head system, one tuned in total resonance can exhibit up to 100 times higher sensitivity to any desired target.
                  That fact alone lead to use of lower electronic amplification, lower electronic instability and much better resistance to thermal changes for the electronic circuit.
                  A RX loop tuned in total resonance will act also as 10 th order band pass filter against any external interference, which will almost eliminate the need of any interference prevention filters.
                  In comparison to off resonance RX loop, one tuned in total resonance is much more sensitive to phase and amplitude changes, which fact can guarantee best depth penetration and discrimination accuracy as can be achieved with any metal detector."

                  Comment


                  • Originally posted by Sun_rise_pt View Post
                    In my personal experience, I think the resonance of the LC circuit of the reception is very important because in addition to conveniently filter all what you are receiving, reducing the window for optimal detection, ie: improving the Q (quality factor).


                    I take the liberty of reproducing the end of doc which refers to the importance of perfect resonance:

                    HTML Code:
                    http://www.nexusdetectors.com/sciencemetaldetectors.html
                    Nexus, a important name for the manufacturers of MD refer also the validity of this concept in a very interesting document and reading accessible even for non-technical people at:

                    "...The best metal detectors regarding depth penetration and discrimination accuracy are the IB detectors tuned in total or as close as possible to total electro-magnetic resonance.

                    The reasons:
                    It is not possible for any kind of loop to achieve higher Q than the Q as a result of electro-magnetic resonance.
                    In comparison to a standard, not tuned in resonance search head system, one tuned in total resonance can exhibit up to 100 times higher sensitivity to any desired target.
                    That fact alone lead to use of lower electronic amplification, lower electronic instability and much better resistance to thermal changes for the electronic circuit.
                    A RX loop tuned in total resonance will act also as 10 th order band pass filter against any external interference, which will almost eliminate the need of any interference prevention filters.
                    In comparison to off resonance RX loop, one tuned in total resonance is much more sensitive to phase and amplitude changes, which fact can guarantee best depth penetration and discrimination accuracy as can be achieved with any metal detector."
                    You may want to continue your discussion here:

                    http://www.geotech1.com/forums/showt...resonant+coils

                    Comment


                    • Dfbowers you're right. This subject is generic for al IB coils, and not only for the IDX Pro, although derived from it ...

                      Comment


                      • Originally posted by szucs_g View Post
                        My IDX is working. I bought BC517. It is good for machine. With the original W3900 coil make a 25 cm for gold ring. I must make a good coil or buy an other. :-(
                        How can I adjust my IDX without oscilloscope? What can I make with VR3? How can I adjust the GEB function?
                        The White's IDX is a concentric 20 centimeter head sees a gold ring. This defect in the head?

                        Comment


                        • Originally posted by szucs_g View Post
                          How can I adjust my IDX without oscilloscope? What can I make with VR3? How can I adjust the GEB function?
                          The White's IDX is a concentric 20 centimeter head sees a gold ring. This defect in the head?


                          OK. My IDX with Whites 3900 concentric coil view cca. 20 cm. This is'nt well...

                          Comment


                          • I set the potentiometer VR3. I noticed that the aluminum foil and the gold ring main difference between hard to do. Until there is a VDI aluminum ball go in my pocket, adjusts the electronics.
                            The tresch not much change in sensitivity. The Sens have not seen for too many changes. The GEB how to set?

                            The original 3900 rolls of 23 cm could not be reached (the old one D. Mark).

                            Can someone give a full description of IDX? Please! Thx! Gábor

                            Comment


                            • I am not familiar with the IDX-PRO, but the procedure for setting the GEB potentiometer might be the same as for the TGSL:

                              For this, you will need a small ferrite slug scavenged from an old radio or possibly a toroid. Verifying correct circuit operation would very difficult without a ferrite slug! Start with the TGSL switched to the all metal mode and set the GB pot fully Counter Clockwise. Start waving the ferrite slug over the coil and advance that GB pot slowly Clockwise until the ferrite slug is rejected or the sound starts to break up. Advancing too much further and silver may be rejected in the DISC mode! This will be a good place to start for
                              rejecting the return signal associated with ground.
                              Regards,
                              Joop

                              Comment


                              • Originally posted by joop View Post
                                I am not familiar with the IDX-PRO, but the procedure for setting the GEB potentiometer might be the same as for the TGSL:



                                Regards,
                                Joop
                                Thank You! Hvala! Köszönöm! Cpocibo! Muchas gracias!
                                This means that a toroidal ferrite is to pack myself. :-)

                                Comment

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