IDX-PRO+VDI

[mohandes]

Firsly you have D3 crossed out in the schematic....

You will need this..

Most have a IN4148 in here... as per silk screen - You can use a 2v7 zener also - fit as per the schematic ( i.e. The zener would go one way around, the dide must go the other way around. ) I think we covered this before, twice




The Disc pot when set CW will reject Iron
The Disc pot when set CCW will NOT reject Iron

The Geb pot when set correctly will reject ferrite

I call the Sens pot the Threshold whish is very confusing I apologise.
The pot tha goes to the two comparators - this sets up a small positive DC level for which signals on BOTH Disc and GEB channels must exceed for a tone.

the pot at the top has its main use when in PP - if set too high the tone rings out continuously. So in PP require to back it off CCW so just no tone.
IN Disc mode leave this pot CW almost fully. This puts more positive DC bias on MPSA13 base - so closer to loud conduction. Works a bit like volume in Disc mode, It does reduce volume of HIT if set CCW

i take more photo
please help
i have not 2,7volt for D3 and use 2.4volt.
THANK you golfnut but i dont mean the professional the main words like : CW and CCW(so sorry man)

please see :

First pic , yellow is U1-pin6 and blue is U8-pin1

seond pic , yellow is U1-pin6 and blue is U8-7

third ,yellow is U8-1and blue is U8-7

forth , yellow U1-pin3 and blue U1-pin6

fifth , blue is U7-pin1 (it is not 400hz,how i adjust it ???????)


EDIT :
my detector have a very bad depth,how i an improve it

[golfnut]

Firsly you have D3 crossed out in the schematic....

You will need this..

Most have a IN4148 in here... as per silk screen - You can use a 2v7 zener also - fit as per the schematic ( i.e. The zener would go one way around, the dide must go the other way around. ) I think we covered this before, twice




The Disc pot when set CW will reject Iron
The Disc pot when set CCW will NOT reject Iron

The Geb pot when set correctly will reject ferrite

I call the Sens pot the Threshold whish is very confusing I apologise.
The pot tha goes to the two comparators - this sets up a small positive DC level for which signals on BOTH Disc and GEB channels must exceed for a tone.

the pot at the top has its main use when in PP - if set too high the tone rings out continuously. So in PP require to back it off CCW so just no tone.
IN Disc mode leave this pot CW almost fully. This puts more positive DC bias on MPSA13 base - so closer to loud conduction. Works a bit like volume in Disc mode, It does reduce volume of HIT if set CCW

[wlewis]

Has anyone in Australia built this for gold prospeting? If so, how does it perform in mineralized soil?

Very relevant question. It seems the 'IGSL TGSL' is better suited for highly mineralized areas.. the schematic shows disc (discard?) and 'fe' block options. Any suggestions are welcome.

[mohandes]

Hi all
i explain all things that say in befor post in this pic please look and tell me :

[mohandes]

please say me how work by pots
GEB
THERSHOLD
DISC 100k
disc 10K
regards

i remove 470 ohm and connect 4.7k bitween pin6&7 U4 and have not sound(ANNIHILATE sound)

[mohandes]

Please Help! I have the IDX kit (from Silverdog) soldered. There were a few parts left (multi turn pot VR3 and 2 diodes - some parts were missing (Resistors).

Now I have found that there is a difference.

The PCB which is displayed in the shop and what i have soldered. Are there different versions?...

This is the PCB which I got (and already soldered):

[ATTACH]26834[/ATTACH]
[ATTACH]26835[/ATTACH]

This is the PCB shown in the shop:

[ATTACH]26836[/ATTACH]


I'm totally confused ....

Hi all guru
now i change my pcb like Dixix ,http://www.geotech1.com/forums/attac...4&d=1382242387
and know just one ? about the U4 and sound,please see this number you know my mean :read all below please

first idea :
the first design by eduardo that exist 47 ohm that connection in U4-pin6 and 2 .

second :

in number #1245 Mr eduardo says ( 47o ohm instead of 47 ohm) he explains for us that you ATTAIN this value by do this :The resistance value depends on the gain of the comparator (LM393). There comparators with little gain and it takes a lower value for the resistance of 470 ohms. I use a 1K trimmer and so you can adjust the desired gain

This version is the one that works best for all. I made some small modifications. This is the best it has worked. Enjoy.

Attached Files

• IDX.rar (56.4 KB, 403 views)

third :
in #1252 eduardo says :

For threshold tone discrimination mode, you have to eliminate the resistance of 470 ohms, and connect a 4K7 resistor between pins 6y7 of U4 (LM393). This way you will get a nice tone threshold discrimination mode. The threshold tone level is adjusted with the potentiometer sensitivity. Greetings. Eduardo.

forth:
in #1307 and #1309

• reg.JPG (24.9 KB, 1012 views)

reiv

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Member

Join DateMay 2012Posts66

Sure this resistance it`s not critical, just helps to get more linear control of volume. With 2k5 you will get start to hear beeping on "1.5" position of potentiometr (with 1-10 scale) and full of volume at "10". Experiment with this resistance and You will see what is all about

FINALLY , which is more correct of this items

thanks

[Koala]

A smaller coil helps a lot. I have a 10.6" DD and a 8" concentric. On damp sand the 8" works much better. I have been tempted to make a 5" DD and give that a try. You will need a small coil to be sensitive to very small targets .

[xlev]

In the uk the soil mineral content is fairly low - east anglia where I am is mainly clay and has low iron content. The IDX works well here - for a basic machine.
There are pockets of Ironstone deposits -normally on exposed raised small ridges - the IDX does not cope well here. Lots of falses, if the soil has rapidly varying mineral content i.e soil to stone with iron and back ,= the geb will only be set for one of these and will false on the other.

A second GEB ch could help set at the phase of the heavy mineral and the usual one set for soil.
Lots of work though.

In short I dont know as I cant test for it.

The if black sand in the US has a similar phase response to your local mineral - then your in with a chance - as the original had a black sand setting.

Carl may furnish you with a more useful answer as his knowledge is greater


S

Thanks for the reply. What kind of coil do you use?

I was thinking that maybe having a DD coil could help with high mineralization?

[golfnut]

In the uk the soil mineral content is fairly low - east anglia where I am is mainly clay and has low iron content. The IDX works well here - for a basic machine.
There are pockets of Ironstone deposits -normally on exposed raised small ridges - the IDX does not cope well here. Lots of falses, if the soil has rapidly varying mineral content i.e soil to stone with iron and back ,= the geb will only be set for one of these and will false on the other.

A second GEB ch could help set at the phase of the heavy mineral and the usual one set for soil.
Lots of work though.

In short I dont know as I cant test for it.

The if black sand in the US has a similar phase response to your local mineral - then your in with a chance - as the original had a black sand setting.

Carl may furnish you with a more useful answer as his knowledge is greater


S

[Koala]

Has anyone in Australia built this for gold prospeting? If so, how does it perform in mineralized soil?

Noticed no one has answered your question and it's got bumped down the thread very quickly.

I don't know. Hopefully someone else can help who has used one of the Classic range in your soil. Did find some good info on VLF for gold prospecting in a PDF do a Google search for "Dave'sGoldbook-printer.pdf".

It's certainly not designed for this job but don't know if it can be made to work where you are.

[wlewis]

Yes I built the coil...

got it.. thanks for the tips.

[golfnut]

,the yellow is Tx and probe on *10, so this voltage is 15.5 volts

This is fine.



Blue is Rx and probe is *1, and it is 120mv

If this is the coil output it is too big -
Measure it at the preamp output -- this should be 200mV or less.



the sens volume i put 10K (or better put it 100k ???)

use the one in the design



.can i use op27 instead of ne5534?

Use the 5534 it has gain, stability, and good noise

[mohandes]

Finish , now need to help me for adjust pots

now my detector is working.
just please tell me about the set pots in this board , my pots like this pic

please help me for final
regards

[mohandes]

DS oo12 looks OK for phase.


Make sure the coil is away from metal items...

If coil output it is really 1.5Volts, Then this is TOO BIG and will saturate the preamp.


I would try and adjust the coil overlap for a smaller voltage.#


If the Rx volts you display is at the preamp output then 1.5Volts is a little too big.

Readjust the coil postion to reduce it.

You may try for the best you can,, then itroduce a small peice of ferrite and move it around the shell to get the best phase and amplitude combination..

200mV or less is perferct and 180 degrees +/-20 seems OK .

S

S

merci Mr golfnut
just my speaker have sound (Continue the sound and dont cut)
for explain more about the pics DS0018 ,the yellow is Tx and probe on *10, so this voltage is 15.5 volts
Blue is Rx and probe is *1, and it is 120mv

the sens volume i put 10K (or better put it 100k ???) .can i use op27 instead of ne5534?
regards

[golfnut]

DS oo12 looks OK for phase.


Make sure the coil is away from metal items...

If coil output it is really 1.5Volts, Then this is TOO BIG and will saturate the preamp.


I would try and adjust the coil overlap for a smaller voltage.#


If the Rx volts you display is at the preamp output then 1.5Volts is a little too big.

Readjust the coil postion to reduce it.

You may try for the best you can,, then itroduce a small peice of ferrite and move it around the shell to get the best phase and amplitude combination..

200mV or less is perferct and 180 degrees +/-20 seems OK .

S

S