TESORO GOLDEN SABRE

[mostafalesnar91]

What I meant is you did not show the coil nulling

google translate is very weak!!!
I did this with a multimeter, move the RX on the TX slowly and reach zero millivolts in AC mode !!!!
Of course, in this method, the angle between RX and TX is not observed, so the amount of sense is slightly reduced!!!!!!!!!!!!!!!!!

[mostafalesnar91]

try to understand this thread https://www.geotech1.com/forums/show...831-Cache-Test
before to ask 'more than one meter'.

The halo effect is not a new topic for me, my friend !!!
In fact, everyone knows that the metal detector senses a little more metal than air due to the oxidation of the metal in the soil and the formation of the halo effect over the years !!!
Now my question is what is the maximum sense of KING COBRA and IGSL and........just in the air and not on the ground ??

[surfdetector]

thanks!!!

What I meant is you did not show the coil nulling

[kt315]

try to understand this thread https://www.geotech1.com/forums/show...831-Cache-Test
before to ask 'more than one meter'.

[mostafalesnar91]

TGSL with a maximum sense of 70 cm for big things is no different with a pin pointer. In fact, it is very weak.
Does anyone know a vlf metal detector that has a maximum sensitivity of more than one meter ??
What is the maximum sense of IGSL and King Cobra ??

[mostafalesnar91]

Mostafa it would have been interesting to see you doing the coil nulling.

thanks!!!

[surfdetector]

In this video, 10 cm must be added to each item, so when a coin is sensed at 15 cm in this video, it is actually sensed at 25 cm, because this video was taken in a city and a place where 10 cm reduces the result of metal sensation. But somewhere outside the city, 10 cm is added to my test result

Mostafa it would have been interesting to see you doing the coil nulling.

[mostafalesnar91]

my tgsl test video with 5.5 inch loop!!!!
https://m.youtube.com/watch?v=I0vJhNWY2kE

In this video, 10 cm must be added to each item, so when a coin is sensed at 15 cm in this video, it is actually sensed at 25 cm, because this video was taken in a city and a place where 10 cm reduces the result of metal sensation. But somewhere outside the city, 10 cm is added to my test result

[SWL]

I connected the coil to the second TGSL board. The signal is clear. This means that either the LF is bad, or minus is weak. I decided to postpone the project until better times.I'd rather do something else

[SWL]

Exactly! I completely forgot to look at the input signal. I'll take a look in the evening. There was definitely no metal nearby

[waltr]

And one more question. Today I nulling the concentric sensor and noticed the distortion of the lower part of the RX sinusoid on pin 1 LF353. What is the reason for this - a bad power supply minus or a step on the TX? Or poor quality op amp?

That is odd and I really do not know why it looks like that.
Take a look at the input, on the RX coil, to the preamp and see if it is there.

Also ensure NO metal is near the coil.
Could be a bad opamp, swap with a new one to see. Do ensure the LF353 is NOT a fake.

[waltr]

So where is the correct phase to watch?

IF Yellow trace is the TX signal, this is the "reference" for measurements.
Then 1.png is the correct measurement since we know that due to the circuit the RX signal will LAG and appear later in time.
Therefore the phase shift is:
Period = 1/11.987kHz = 83.5us
Shift = 45.2/83.5 *360 = 194.8 degrees

[SWL]

And one more question. Today I nulling the concentric sensor and noticed the distortion of the lower part of the RX sinusoid on pin 1 LF353. What is the reason for this - a bad power supply minus or a step on the TX? Or poor quality op amp?

[SWL]

So where is the correct phase to watch?

[waltr]

How can a coil like this work? And yet it works perfectly, even though it is balanced where tx is leading by app. 200 degrees. Won't the phase detectors sample at the wrong intervals? Wouldn't they be off by some 180 degrees?

I posted this above:
You need to look at the SAMPLING switch timing also. Then know that the next stages, differential circuits (I said integrators above in error), are AC coupled so only give a response to Changes.