Lrl from Italy

[FrancoItaly]

Originally Posted by humhum

I Think that with Franco Xtal LRL , Lucky frequency can be is with 9.736,305 Mhz .

According to my experience my lrl works with these frequencies: 2.8Mhz (CD4046 version) - 3 - 4 - 6 - 8 - 10Mhz. It is possible that with high frequencies, for example 9 or 10MHz, the sensor stage amplifies more, since TR3 and TR4 are in practice a high pass active filter, through the capacitors placed between emitter and ground.

[humhum]

Hi Franco, this is part High Freq. from main Resonant Frequency of Gold. But here problem is that max. operation Output Freq (OSC) of cd4046 is up to 1.6 Mhz. (Datasheet)

If I not know wrong OSC of 4046 + input Freq OSC from Stylus Antenna make Mix and giving ference freq for Output (for example 1Khz), so like Radio mixer.

If is so OSC from CD4046 not will High Frequency 9 or 10 Mhz .

[FrancoItaly]

Originally Posted by humhum

Hi Franco, this is part High Freq. from main Resonant Frequency of Gold. But here problem is that max. operation Output Freq (OSC) of cd4046 is up to 1.6 Mhz. (Datasheet)

If I not know wrong OSC of 4046 + input Freq OSC from Stylus Antenna make Mix and giving ference freq for Output (for example 1Khz), so like Radio mixer.

If is so OSC from CD4046 not will High Frequency 9 or 10 Mhz .

There are 2 versions of my lrl, one is with CD4046 and it works (in my case) at 2.8Mhz, it is not convenient a higher frequency (over 3Mhz absorbs too much), however with the normal type it is not possible to go further, but it is not necessary. The version with the quartz, as already mentioned, can work from 3 to 10Mhz. The TR2 stage is called mixer, but not in the sense used in radio receivers, in fact here there is not a frequency conversion (we would need very wide signals and here is not the case), but rather an amplitude modulation on the contrary, in fact the signal to lower frequency (for example 8Mhz) is modulated (I would say almost disturbed) by the much higher frequency signal coming from the antenna (about 100Mhz). Regarding the frequency of resonance of gold I do not think it is possible to tune my lrl, also because you first need to know the value of this frequency, if it exists.

[humhum]

I am not sure ,but with your Tr first version if we use Xtal with 9.xxxxx Mhz can be will is possible.

[FrancoItaly]

Originally Posted by humhum

I am not sure ,but with your Tr first version if we use Xtal with 9.xxxxx Mhz can be will is possible.

The only practical way to check if there is a specific frequency for gold is to try different frequencies. However, as I have already said, we must keep in mind that the sensor stage is practically a high gain high pass filter, therefore it amplifies the frequency of 9MHz more than a 4MHz frequency, for example. When using the 4MHz frequency, the value of C13 / C14 must be increased to achieve the same gain. Or you can increase the gain in the stage display.

[Haydar]

What should be the appropriate antenna length in the terrain?

[FrancoItaly]

Originally Posted by Haydar

What should be the appropriate antenna length in the terrain?

In the range 30/40cm, more length=more sensibility.

[Haydar]

Is it possible to make metal distinction by measuring frequency?

[Haydar]

What does it mean when the receiver voltage rises or decreases while roaming the terrain? In some areas, the voltage rises, and in some regions, I noticed that the receiver voltage decreased.

[FrancoItaly]

Originally Posted by Haydar

What does it mean when the receiver voltage rises or decreases while roaming the terrain? In some areas, the voltage rises, and in some regions, I noticed that the receiver voltage decreased.

I never checked if the signal decreases in some locality, perhaps it depends on the type of terrain. If the gain is excessive in addition to the compass effect, the sky effect also appears, ie a signal appears tilting the lrl downwards or upwards.

[FrancoItaly]

Originally Posted by Haydar

Is it possible to make metal distinction by measuring frequency?

If you mean the frequency of the quartz oscillator I think it does not affect the sensitivity to a certain metal, if you refer to the frequency of the signal from the antenna I do not know, it is not very easy to measure, you can vary the frequency of L1 / C10 and check if the sensitivity to different metals changes.

[mustefa ubram]

hi to all freinds
hi franco
What is your opinion about this design pcb 8mhz v.r?
I could not get the result from previous designs

[FrancoItaly]

It is difficult to judge. To avoid self-oscillations I prefer to use a pcb only for the sensor stage (double-sided type), with the components welded on the upper face and with the lower face connected to ground. Otherwise the risk is that the stadium oscillates even with a low gain. Furthermore it is better to set up the sensor stage when its output is still not connected to the display stage.

[Dubulumach]

Get out one preamplifier stage and lower your gain as much as possible but still enough to detect the phenomenon, while cut sky/ground effect.

I will give you one idea. Add several different oscillator stages besides original 8MHz, for example 1MHz, 20Mhz, 100 MHz, and mix very small oscillator's output amplitude on the base of 1st transistor. On this way you will have very wide band detection.Amplitudes must be very low to avoid oversaturation of preamplifier, interferation and slope eadge modulation.Also good narrow band pass filter should be added after amplitude detector.

Interesting project but need a lot of mods.
All credits go to Franco Italy.

and remember:
NOISE IS YOUR FRIEND becuase can help you to find a lot of gold coins.

[FrancoItaly]

Originally Posted by Dubulumach

Get out one preamplifier stage and lower your gain as much as possible but still enough to detect the phenomenon, while cut sky/ground effect.

I will give you one idea. Add several different oscillator stages besides original 8MHz, for example 1MHz, 20Mhz, 100 MHz, and mix very small oscillator's output amplitude on the base of 1st transistor. On this way you will have very wide band detection.Amplitudes must be very low to avoid oversaturation of preamplifier, interferation and slope eadge modulation.Also good narrow band pass filter should be added after amplitude detector.

Interesting project but need a lot of mods.
All credits go to Franco Italy.

and remember:
NOISE IS YOUR FRIEND becuase can help you to find a lot of gold coins.

The idea seems good, but difficult to apply on the sensor stage, which in practice is an active high pass filter preceded by a sort of mixer (TR2). In practice the gain is optimized for a certain frequency, a separate sensor stage should be built for each frequency. In my opinion the frequency of the oscillator is not very important, let's not forget that the phenomenon comes from the antenna and is filtered by L1 / C10 and probably there is a carrier of about 100Mhz which is modulated by the phenomenon. On the basis of TR2 two signals arrive, the phenomenon and the oscillator signal. This is not frequency conversion, it is not a linear mixing, it simply increases the amplitude of the oscillator signal. The fundamental requirement for the operation of my lrl is that there is some transmitter in the 100Mhz band, for example private radio stations or satellite broadcasters.

[mustefa ubram]

hi franco
Franco I corrected according to your guidance

[FrancoItaly]

It seems to me that it is fine, but the definitive proof is the good functioning. I must admit that it is not easy to set up, in this period I am working on a sensor stage of a lrl that I realized long ago, its sensitivity is low, while revealing the phenomenon. I think the reason is the low beta of the transistors but unfortunately where I am I don't have the possibility to try other transistors. I have yet to try removing R10 / C13 to get the maximum gain.

[sakher]

Hello my frinds
where is the best points on the circuit to test frequency?

[FrancoItaly]

If you mean the input frequency of the sensor stage you can only calculate it theoretically with the values of L1 / C10 + about 10pF of the parasitic capacitance of the TR2 base / emitter, or you can use an external oscillator and check for what frequency there is a variation to the out of the sensor stage. However the most important thing is to establish which is the best frequency on the test field, C10 can be 10 or 15 or 20pF, or nothing, only the base / emitter capacity.

[sakher]

Originally Posted by FrancoItaly

If you mean the input frequency of the sensor stage you can only calculate it theoretically with the values of L1 / C10 + about 10pF of the parasitic capacitance of the TR2 base / emitter, or you can use an external oscillator and check for what frequency there is a variation to the out of the sensor stage. However the most important thing is to establish which is the best frequency on the test field, C10 can be 10 or 15 or 20pF, or nothing, only the base / emitter capacity.

Thank you Mr.Franco, Is there required frequency range that i must measure it ?

[FrancoItaly]

Originally Posted by sakher

Thank you Mr.Franco, Is there required frequency range that i must measure it ?

There is no particular frequency required, it is just a matter of finding the best value for C10. I found that my lrl (in my country) also works well with L1 = 2 turns and C10 = 10pF, or L1 = 3 turns and C10 = 22pF. I think that the phenomenon emits in the range 80 - 120Mhz and that it is important that there are radio or TV stations that transmit in that frequency range that act as a "stimulus". This could explain why my lrl (but I also believe others) does not work in certain areas.

[sakher]

Thank you very much

[taher5739]

Hello dear franco
I have a question from you
Have you tried an antenna amplifier on the test field?
If your answer is yes What has Results?
Thanks for your patience.

[FrancoItaly]

Originally Posted by taher5739

Hello dear franco
I have a question from you
Have you tried an antenna amplifier on the test field?
If your answer is yes What has Results?
Thanks for your patience.

In my case the sensitivity has increased by about 20%. The main advantage is that the antenna amplifier compensates for the fact that the sensor stage has not been adjusted for the highest possible sensitivity.

[taher5739]

Sensitivity for gold or silver has increased, or both?
I want to know if adding the filter to the antenna amplifier section ,
Can make a distinction for copper or gold?
i wish you success in life