Lrl from Italy

[brain]

by franco can you tell us what is in your test area as metal and what is the depth?

[FrancoItaly]

by franco can you tell us what is in your test area as metal and what is the depth?

Unfortunately I no longer have a field where to do the tests, there is only a point on my ground where there is a good signal, I don't know what is buried there. I use this place where I do comparative tests.

[liudengyuand]

I suggest that you change the 3.3 volt air supply voltage, you can use a lithium battery to do power

[Sally]

Hello Sir Franco, I had sent an email to you regarding phenomenon. If you have time please i need your reply.

Thank you,
Sally

[Jeg]

L1, C10

Hi Franco
I would like to ask you what is the frequency range approximately in the tank circuit of L1 and C10.


ps. By the way, L1 is a 3T air core coil. What is the diameter of the core?



Best regards

[FrancoItaly]

Hi Franco
I would like to ask you what is the frequency range approximately in the tank circuit of L1 and C10.


ps. By the way, L1 is a 3T air core coil. What is the diameter of the core?



Best regards

I think the frequency is around 100Mhz and the coil diameter is 10mm.

[Jeg]

I think the frequency is around 100Mhz and the coil diameter is 10mm.

Thanks a lot Franco.

[kaveh]

Hello Mr. Franco and dear friends Why does the circuit of some friends sense iron? What is the reason? Wishing the best for you and everyone

[FrancoItaly]

Hello Mr. Franco and dear friends Why does the circuit of some friends sense iron? What is the reason? Wishing the best for you and everyone

According to my experience my lrl is not sensitive to iron, but I also believe the other lrls, I believe that iron is not able to generate or in some way affect the phenomenon, but it is just my personal idea.

[Jeg]

This design and circuit of Mr. Franco, which has been slightly strengthened by our good friends, and of course it is much better to increase the distance of the sensor from the discipline. However, it is very powerful and sensitive.

Hi babak
Is that possible to share the circuit that corresponds to that board of yours? I dont see any Ic's in original franco's circuit. Thanks

[Jeg]

Hi Franco
Do you remember what is the pk-pk voltage value of the composite signal that reaches the base of Tr2? I mean about the product of mixing especially when we hit the right harmonic across the LC tank. Approximately.

Thanks in advance
Merry Christmass and happy new year to all.

[FrancoItaly]

Hi Franco
Do you remember what is the pk-pk voltage value of the composite signal that reaches the base of Tr2? I mean about the product of mixing especially when we hit the right harmonic across the LC tank. Approximately.

Thanks in advance
Merry Christmass and happy new year to all.

The value is very small, I don't think it's possible to measure it. The only reliable measurement is the sensor stage DC output and all changes in component values are made solely by observing the changes in the output voltage.

[Jeg]

Thank you Franco. I ll give it a try! :-)

[Jeg]

Hi all
Hi Franco

The input P1 trimmer seems that doesn't serve the purpose of its use. I tested two crystals 4M and 16M. The signal at the input of tr2 can not be less than about 50 mV. Imho, your initial design with many 1pf caps in series is a better approach for to increase impedance.

A second issue is the input tank coil. More turns than 3 will give higher sensitivity and higher Q. I made a coil of 8T on a 6mm former to test.

I'd like to ask if you have tested 90 degrees different orientation of the input tank coil than what you currently use. In other words, the coil on your board looks at the sides. Have you tested the operation when it looks forward?

Regards

[FrancoItaly]

Hi all
Hi Franco

The input P1 trimmer seems that doesn't serve the purpose of its use. I tested two crystals 4M and 16M. The signal at the input of tr2 can not be less than about 50 mV. Imho, your initial design with many 1pf caps in series is a better approach for to increase impedance.

A second issue is the input tank coil. More turns than 3 will give higher sensitivity and higher Q. I made a coil of 8T on a 6mm former to test.

I'd like to ask if you have tested 90 degrees different orientation of the input tank coil than what you currently use. In other words, the coil on your board looks at the sides. Have you tested the operation when it looks forward?

Regards

The signal at input TR2 is much smaller than 50mV, consider that the sensor stage is composed of transistors with a gain (direct current) of over 500 each, so the maximum gain is 500X500X500 and the stage would be in saturation without amplifying. I added the trimmer to better adjust the signal to base on TR2 and I found no difference between the two modes. I tried to increase and decrease the number of turns, the lrl only worked with 2 or 3 turns. You have to consider that it is a resonant circuit and increasing the turns decreases the frequency. In the 20 Mhz or 14 Mhz version the L / C is varied to tune on a harmonic of the oscillator and increase the efficiency of the TR2 mixer. Regarding the position of L1 I have not found any difference.