TM 808 White's

[berreizeta]

Making any changes here is going to drive you crazy....

I put the video on now, if I can ....

[berreizeta]

I have remade the coils from circular to square, retuned both to 6533hz, it works now...

The LED stays on up to 43cm

[pito]

In my case, the coil with the diode has no capacitor = no resonance. The white coil is 10cm/100 turns ?
If you have similar range for not tuned coil and 35 mA then your Tx is very good.
Show the picture of toroid.

[berreizeta]

I think we're finally on the right track.

The LED starts to light up at 20cm

The two coils tuned to 6533

[MDfanatic]

It can locate a barrel of oil 3m deep (tested on ground), a bigger target (i.e. a car) would be detected at greater depths (maybe even 5-6 meters by approximation).

[chamee25]

what is max depth on this device?

[pito]

You may have less power radiation from Tx, my Tx consumes 100 mA. Check again how much you have on Rx coil from 8m.
The diode starts to glow at 18 cm.

[berreizeta]

This circuit that you use corresponds to the TM800


and the one I am using is the TM808,


I don't know what differences it may have when comparing the values

[pito]

How do you do that ?



At 1, I have 15V and 36mA to the coil.

Low sensivity :

https://youtu.be/Z1aTZIuyVIo

Good news for you, as I remember you have 20 mV at 8 m, I have 10 mV at 6 m, so you have better Rx/Tx sensitivity. I don't think you balanced the coils deep enough.
My oscilloscope has a maximum sensitivity of 5 mV/div and I have a straight line when the coils are balanced, so I add an amplifier to see that weak signal.

What do you have on RCV P1 ?
In 2, I have 0.3V with the coils in null: = maybe you need less , XY mode oscilloscope will answer hat.

[pito]

I burned Q1, installed another one and now I have 6V on the collector and it was 12 V.
Low sensivity : = You need to use XY mode in oscilloscope because phase changes are more visible than amplitude, for Y channel I am using testing coil laying on the floor.
Without amplifier compensation is less than 1 mV, after amplification it is about 1V.

At 1, I have 15V and 36mA to the coil. = To compare the Tx power with mine, you need to have the same test coil, say 100 turns, coil diameter 10 cm, wire 0.5.
The amplitude at the collector is not the best parameter.

[pito]

I did it like this

[berreizeta]

How do you do that ?



At 1, I have 15V and 36mA to the coil.



In 2, I have 0.3V with the coils in null:



Low sensivity :

https://youtu.be/Z1aTZIuyVIo

[pito]

Now I have 130cm, with some inferences ( image is shaking )

https://www.youtube.com/shorts/nC5ajrUm47Q

[pito]

With amplifier I have 110 cm.
Distance between coils don't affect the sensitivity much, here are the coils even closer.
The smaller the distance, the more difficult it is to balance.

[ivconic]

Just Tx and Rx tuned coil connected to oscilloscope, reaction noted at 80cm, with amplifier should be over 1m. I not happy with power of Tx, should be 2x more, probably transistor not good as in original...

I think coils are too close on your video...
Set them at 65-70cm apart and check again...