TM 808 White's

[berreizeta]

The boards arrived

[pito]

75cm = you need 90cm = good antennas and good electronics from post # 243, what is Tx current ? The metal around it does not affect the sensitivity.
look post #235, 238, 239.
Coils = the most rigid is duralumin rod, if it is difficult to bend, use a torch.
If you are going to use pipes, fill them with sand.

Before making final coils you can make good testing coils using soft copper tube, easy to bend .

[ivconic]

...I still haven't decided whether to make them in aluminum or copper, hollow or solid tube... which is better?

I made "antennas" from duraluminum "solid tubes".
Hard to bend but also robust for terrain work and rough handling/transporting.
Also less weight then copper ones.
Duraluminum is probably the best choice.
But you can use whatever you can obtain.

[berreizeta]

A 20cm frying pan about 75cm away, but I have a lot of metal around, I suppose this will influence the detection

The coils I am using are not the final ones, they are smaller and are not well finished, just to test the circuit.

I'm going to make them while I wait for the cards to arrive, I still haven't decided whether to make them in aluminum or copper, hollow or solid tube... which is better?

[pito]

This is good but not precise, I didn't test this way because the white coil can represent bigger object than diameter of it, for example plate 50 cm in diameter, do that with cola can.

[berreizeta]

Tuned coil, one meter away

[pito]

Cola can over 1m. Not measured precisely. = ??? ,
In your video, the pipe is detected from a distance of about 60 cm, and there is more metal in it than in a can of coke.

[ivconic]

It's obvious that we don't understand each other at all, no problem.
Do the whole detector and when you do then we will see what the real performance is.
In any case, this forum won't hurt a little more ideas and experiments.
I support that.

[pito]

The system means post # 241and #242, not a complete circuit.
Cola can over 1m. Not measured precisely. = 90cm, now just oscilloscope, when finished with complete electronics 150cm.
use as minimal to be able later to achieve balance. = my minimal is 20cm. Smaller distance = harder to achieve balance, does not reduce sensitivity.


Pic from my museum.

[ivconic]

And from what distance it is react to the can?
The goal is 90cm.

Telling you what? = My Tx - Rx system is 50% more sensitive. 40cm Vs 60 cm

Cola can over 1m. Not measured precisely.
...
No it was not my point. Your "Rx system" is not more (or less) sensitive because it is not detector yet.
It is just wire and led. Once you make a real detecotr out of it ;you will see the real performances.
Led indicates the distance from coils which you will have to use as minimal to be able later to achieve balance.

[pito]

And from what distance it is react to the can?
The goal is 90cm.

Telling you what? = My Tx - Rx system is 50% more sensitive. 40cm Vs 60 cm

[berreizeta]

With the small coil tuned to 6533 Hz the LED stays on up to about 30cm.

I get this on the XY oscilloscope with a can

[ivconic]

...My LED coil is start glowing at 65 cm, masking tape mark is at 60 cm...

Telling you what?

[pito]

For comparison, a 30 cm diameter coil, black mark = 90 cm.

[pito]

It is better to use LED + white coil with no resonance capacitor which allows to test just Tax, then when you happy with the results you use Rx with resonance capacitor.
My LED coil is start glowing at 65 cm, masking tape mark is at 60 cm.

.