IDX-PRO+VDI

[h9361]

The discrimination of the low tone of the iron is done through R43, which is connected to the LM393 comparator circuit. Don't worry, the circuit works as is.

Thanks.
About your words " I can tell you that when the detector's main Discrimination potentiometer is in the minimum position, the low tone (the iron tone) doesn't work."
If you put main disc in minimum position, so high tone always on.
As you know, ( if i remember) ferrous metals cause increasing amplitude of RX frequency.
Your Iron part exactly check this amplitude voltage and uses a threshold pot for this voltage changing.

[eduardo1979]

The discrimination of the low tone of the iron is done through R43, which is connected to the LM393 comparator circuit. Don't worry, the circuit works as is.

[h9361]

In principle, it should work fine by adding the BF245, or a J113 as well. If there's any compatibility issue, you could add a 100K resistor in series with the JFET's gate. Regarding the operation of the two tones, I can tell you that when the detector's main Discrimination potentiometer is in the minimum position, the low tone (the iron tone) doesn't work. Only the low tone works when you start increasing the discrimination potentiometer level. Then there's a VR2 IRON trimmer, which is used to prevent minerals from registering.

Dear eduardo,
I checked your schematic, there is not any connection between main DISC and Iron tone.
I think Iron tone work independently, are you sure?

[h9361]

In principle, it should work fine by adding the BF245, or a J113 as well. If there's any compatibility issue, you could add a 100K resistor in series with the JFET's gate. Regarding the operation of the two tones, I can tell you that when the detector's main Discrimination potentiometer is in the minimum position, the low tone (the iron tone) doesn't work. Only the low tone works when you start increasing the discrimination potentiometer level. Then there's a VR2 IRON trimmer, which is used to prevent minerals from registering.

Thanks.
As you know, Audio frequency of IDX pro is near 400Hz.
schematic of #4412 (added your Iron pot), if i add your low part to my IDX, Can you tell me what my low frequency will be? exp, 200Hz or?
See attached, Audio frequency of your schematic and IDX pro.

[eduardo1979]

Thanks for your nice schematic.
As you know, i have built IDX PRO and i am trying to add it a second tone.
I checked your schematic and tried to get only its second tone part, it is attached.
Is it possible to check it whether it has any error or not?! I want to make your IRON part as a separated PCB for my IDX.

I have a question about Discrimination of your schematic. In your model, we have two pots, one for DISC and one for IRON.
Suppose, i adjust DISC to point that it does not detect Iron. Then, i adjust Iron pot so that it does not detect ground, only IRON. Other words, it acts like a threshold for IRON or minerization?

In principle, it should work fine by adding the BF245, or a J113 as well. If there's any compatibility issue, you could add a 100K resistor in series with the JFET's gate. Regarding the operation of the two tones, I can tell you that when the detector's main Discrimination potentiometer is in the minimum position, the low tone (the iron tone) doesn't work. Only the low tone works when you start increasing the discrimination potentiometer level. Then there's a VR2 IRON trimmer, which is used to prevent minerals from registering.

[h9361]

Hello.
Here's a schematic I designed many years ago, and everything works perfectly, just as you want. It has a trimmer that allows you to adjust the level of iron discrimination. Hot stones and minerals aren't detected with any tone; only iron registers a low tone, which increases as the discrimination level is raised. Non-ferrous objects register a high tone. This detector is exactly what you're looking for. The circuit is 100% correct and tested.
I wish you much success.

Thanks for your nice schematic.
As you know, i have built IDX PRO and i am trying to add it a second tone.
I checked your schematic and tried to get only its second tone part, it is attached.
Is it possible to check it whether it has any error or not?! I want to make your IRON part as a separated PCB for my IDX.

I have a question about Discrimination of your schematic. In your model, we have two pots, one for DISC and one for IRON.
Suppose, i adjust DISC to point that it does not detect Iron. Then, i adjust Iron pot so that it does not detect ground, only IRON. Other words, it acts like a threshold for IRON or minerization?

[eduardo1979]

Thanks.
Dear eduardo
we must remove ferrite in both one and two tone mode.
In my PCB ( post #4407), ferrite can not be removed on two tones.
Do you think your attached (IDX PRO-2 Tones) can do it?
In my test, Since the PCB (two tones) can not remove it, so it will detect any ground or minerization.
So, we have a very unstable mode like a VLF that has not any GB process.

Hello.
Here's a schematic I designed many years ago, and everything works perfectly, just as you want. It has a trimmer that allows you to adjust the level of iron discrimination. Hot stones and minerals aren't detected with any tone; only iron registers a low tone, which increases as the discrimination level is raised. Non-ferrous objects register a high tone. This detector is exactly what you're looking for. The circuit is 100% correct and tested.
I wish you much success.

[h9361]

First, did adding the 4.7V Zener diode solve the overload problem? The PCB layout corresponds to the IDX PRO 2 TONES schematic, except for the CD4060, which performs the same function as the CD4024. If this schematic doesn't suit you, you can use the CLASSIC 3-2 TONES schematic.

Thanks.
Dear eduardo
we must remove ferrite in both one and two tone mode.
In my PCB ( post #4407), ferrite can not be removed on two tones.
Do you think your attached (IDX PRO-2 Tones) can do it?
In my test, Since the PCB (two tones) can not remove it, so it will detect any ground or minerization.
So, we have a very unstable mode like a VLF that has not any GB process.

[eduardo1979]

Thanks.
I have a problem, i used two tones pcb ( attached).
First, i remove ferrite in one tone mode using GB pot.
Then, i switch to two tones but i can not remove ferrite in this mode.
I think GB is not working on two modes and it is very very unstable on ground and we have Continuously IRON tone!
I think schematic of the two tones is not correct and need to be edited.
Has anyone been able to solve this yet?

First, did adding the 4.7V Zener diode solve the overload problem? The PCB layout corresponds to the IDX PRO 2 TONES schematic, except for the CD4060, which performs the same function as the CD4024. If this schematic doesn't suit you, you can use the CLASSIC 3-2 TONES schematic.

[pechkata]

Thanks.
I have a problem, i used two tones pcb ( attached).
First, i remove ferrite in one tone mode using GB pot.
Then, i switch to two tones but i can not remove ferrite in this mode.
I think GB is not working on two modes and it is very very unstable on ground and we have Continuously IRON tone!
I think schematic of the two tones is not correct and need to be edited.
Has anyone been able to solve this yet?

There should also be a third tone—a background sound.

https://www.youtube.com/shorts/H6ZfXZA6NHg

[h9361]

Hi.
A large part of this problem is solved by adding a 4.7V Zener diode in parallel with resistor R22, connecting the diode's anode to pin 1 of U3 and the diode's cathode to pin 2 of U3. Let us know how it goes.
I have attached the diagram with the modification.

Thanks.
I have a problem, i used two tones pcb ( attached).
First, i remove ferrite in one tone mode using GB pot.
Then, i switch to two tones but i can not remove ferrite in this mode.
I think GB is not working on two modes and it is very very unstable on ground and we have Continuously IRON tone!
I think schematic of the two tones is not correct and need to be edited.
Has anyone been able to solve this yet?

[eduardo1979]

Hello dear Carl
My IDX is working nice with my coil but there is still a problem.
Audio of My IDX will be cut off if i close any medium or big size targets to coil (5-10cm)!
For exp, i have not any audio for a 10 cm (diameter) steel bowl from 10-12cm distance.
I checked it on scope, i have a big overload.
Do you have any suggestion for solving this?

Hi.
A large part of this problem is solved by adding a 4.7V Zener diode in parallel with resistor R22, connecting the diode's anode to pin 1 of U3 and the diode's cathode to pin 2 of U3. Let us know how it goes.
I have attached the diagram with the modification.

[irmasirmas1234]

Skema PCB metal detektor IDX pro 2 tone

[Carl-NC]

As Orbit says, all detectors will overload at some point. Normally, the gains of the various stage are set up so that nothing overloads on the worst expected ground. After that, reducing the RX gain just reduces sensitivity. If you are not overloading on ground then I would leave the gain as high as possible. If a target overloads it, just lift the coil.

[pito]

check what going on on U6 output and Q3 base when sound is despairing