IDX-PRO+VDI

[Orbit]

Thanks
You right, my noise is low by the changing.
I can not understand bst 52.

The current of the collector should be a little higher in the case of bst 52 is 1A darlington so that the transistor absolutely does not overheat and the speaker does not break. But I think Karlo's proposal might be better..

[Carl-NC]

In your LM386, gnd is the pine 7 or _VB?

-VB

[h9361]

-VB

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?

[h9361]

-VB

Dear Carl
Do you think the overload is because of more gain in preamp (R2/R1=180)?
Do you think i should decrease this to lower like 150 or 120?

[h9361]

The current of the collector should be a little higher in the case of bst 52 is 1A darlington so that the transistor absolutely does not overheat and the speaker does not break. But I think Karlo's proposal might be better..

Hello
Dear Orbit
Do you have any suggestion for #4398 post?
Thanks

[Orbit]

Hello
Dear Orbit
Do you have any suggestion for #4398 post?
Thanks

What you described is normal for idx! Even factory idx devices with the original coil have an overload effect on targets that are 10cm and larger near the coil! This is absolutely normal behavior for Whites idx Clasic 3, Whites ID.. Don't worry about it!

[h9361]

What you described is normal for idx! Even factory idx devices with the original coil have an overload effect on targets that are 10cm and larger near the coil! This is absolutely normal behavior for Whites idx Clasic 3, Whites ID.. Don't worry about it!

Thanks.
I think this overload distance is very high.
For exp, i have an overload for smoke foil from 10cm distance.
Do you think i should decrease Gain preamp?

[pito]

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

[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.

[irmasirmas1234]

Skema PCB metal detektor IDX pro 2 tone

[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.