IDX-PRO+VDI

[h9361]

What is surprising or new about that? It is simply a combined target/ground signal; you subtract the magnetic/ground component, all while keeping in mind the masking effect caused by the transmitting coil's field (specifically the field itself) in the near-surface zone.

Thanks for your replying.
All of my tests was Air test.
Subtracting magnetic/ground in Air test?!
All testing was based on identical situations, coil size, coin and big targets.

[Smirnov-Arta]

Thanks...

What is surprising or new about that? It is simply a combined target/ground signal; you subtract the magnetic/ground component, all while keeping in mind the masking effect caused by the transmitting coil's field (specifically the field itself) in the near-surface zone.

[Carl-NC]

Even with a low-impedance driver and a parallel cap you are still limited by the voltage compliance of the driver. If the driver supply is 8V then the peak-to-peak coil current is limited to

i(t) = 8V/(2*PI*6600*580uH) = 333mA

If this were not true, then it would imply that you could simply reduce the 47Ω resistor to get more current. But what you will see instead is an increase in waveform distortion as the current becomes more like a triangle wave, while the peak current does not increase.

[h9361]

Option - thicker wire or higher supply voltage....

Thanks.
I have tested several detectors with the same size coil and targets.
According to my tests, there is a main question.
All detectors detects coins approximately from a the same depth, but there is a big difference for big targets.
For exp, some detectors detects the Steel tray (50cm Diameter) More than 50 cm depth difference!
What is strange is that all have a identical depth for coins!
Some believes that frequency plays a key role (lower frequency)!

[nejdet]

Option - thicker wire or higher supply voltage....

[h9361]

The current through a coil (inductor) is



You can vary v(t), or f, or L to change the current. I don't see how the TC4427 changes anything.

[Carl-NC]

The current through a coil (inductor) is



You can vary v(t), or f, or L to change the current. I don't see how the TC4427 changes anything.

[h9361]

I don't understand how your idea will increase the TX current.

First, i produce pulse using 555, then connect to tc4427.
It is a mosfet driver 1.5A.

[Carl-NC]

I don't understand how your idea will increase the TX current.

[h9361]

Dear Carl
Is it possible to tell me your opinion about my idea?
Thanks

[Aleks85]

There's no point in arguing, soil can be very different, sometimes the readings in the air are pleasing, but in real digging it's quite the opposite.
Let's each stick to our own opinions.

[h9361]

No, it's not 50% more depth than other detectors. It's about the same as most other high-end detectors. Minelab claims 50% more "power" but (a) that's a meaningless term in metal detectors and (b) if they mean field energy then it represents a 7% increase.

I simulated my idea.

[pito]

Tl, as the soil has an effect.

,
soil is not reducing sensitivity, you can detect at the same distance trough box of soil as in the air the sensitivity or trough concrete wall.

[pito]

I doubt you'll succeed. The higher the TX power, the greater the influence of the ground. - that's what I think.

Knowing influence we can subtract it from signal, we have also ground balance, reduction of influence 2 kHz frequency, lifting Rx coil from the ground as they do in TX/Rx models and more can be done.

[Aleks85]

This is why a metal detector has better sensitivity when tested in air, but less sensitivity in soil, as the soil has an effect.