IDX-PRO+VDI

[szucs_g]

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

[szucs_g]

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...

[szucs_g]

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?

[Sun_rise_pt]

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

[dfbowers]

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:

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/showthread.php?t=6860&highlight=resonant+coils

[Sun_rise_pt]

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:

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."

[barbaposa]

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

greetings

[szucs_g]

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. :-(

[dfbowers]

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

[Sun_rise_pt]

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?

[barbaposa]

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

[Schatztaucher]

thanks for the info :-)

[Sun_rise_pt]

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.

[Schatztaucher]

the partlist of kt315 thread

[joop]

Been following your posts, mikeBG. You have some interesting observations! I am trying to understand the IDX-pro TX and RX circuit with the help of LTSPICE...

The ultimate test would of course be a side by side comparison in the field of the standard IDX and your frontend. Will it be more sensitive?