Hi Nicolas
I'haven't designed this pcb for this purpose, but I used an older pcb (that I designed as antenna for another Lrl) and at the beginning I wanted to build a RF sniffer in FM range as front end stage of my Lrl. This circuit works well as lrl but not as amplifier but as oscillator. I post here again my pcb where the pcb is also in its real dimensions. I have not really measured the capacity between strips. Try (with your pcb) a small capacitor ( 1 pF or less ) between TR3 collector and TR1 base, perhaps maybe you'll get lucky and can get an oscillation.

Best Regards

hi
 

Dear Franco:
Waiting for more pictures of close-circuit and video if possible.
And how we can use variable frequency by country in which we live.
The batteries used what voltage is it? I put a picture attached and I hope to clarify what there is inside the circle.
I ask you to forgive me for I am new in this regard.

Hi all
many thanks to You Francoitaly for publishing your knowledge here.
perfect PCB nicolas , thank You , but where is L1 ? may it be separate from PCB? or is forgotten on your design?

All the best
matrix

Hi All
I think that the frequency isn't important and depends on the characteristics of the circuit, it's around 5Mhz. Inside the circle there is L1. You must remember that the Lrl is a passive receiver/converter, It transforms the "phenomenon" by modulating an existing signal (the 5Mhz oscillator). As I said before I'm not sure that Nicoals' pcb works well because in my pcb the oscillations are generated by a parasite link from TR3 collector and TR1 base. If the oscillations are between TR3 and TR2 the "phenomenon" cannot influence the oscillator. I spent a lot of time to try to understand this circuit, other types of oscillators don't work.

Best Regards

Hi matrix thanks

the placement for L1 is betwenn J1 and J3 look here

Hi dear Franco I put between Tr1 and Tr3 value of capacitor 1 ..to. 3 pF is good

But on the DC output is between 7 and 9.88V and not 2 to 4V. Yes oscillation is

I put that later because now I have problem with ISIS.

I believe that this circuit does not work.frq is hight .




We need to lower frequency about 20khz

Hi Nicolas
You have to lower the value of the capacitor C5 (330 pF or 270 pF) or the capacitor C7 (470 pF) then adjust the variable capacitor C6 for 2-5V at output, the important thing is that output is not saturated. Remember that few picofarad are sufficient to bring the output from zero to max voltage.

For mustefa ubram
The circuit works very well with this frequency (only with this frequency). The battery are 2 X 9V battery for 18V power.

Best Regards

Hi Franco.
I believe that this schematic works very good at your area, but don't work at my field test. I afraid that "phainomenon" is not strong at my area. Also Alonso's PD, PDK, Mineoro Fg80, DCH 85 etc don't catch the phainomenon. Only a modificated MFD by Andy flind catch it a little.
Maybe i must try at other areas.

Regards:)

Hi Geo Italy or Grece is the same region almost no big difference.

Yes this shematic i think work good and better.
I want to try to see change with the frequency of detection of each metal Detected

Hi Nicolas
Perhaps you can try other frequencies but you must remember that the "heart" of the circuit are L1, C1 and C2, with these values and the parasitic capacitor there is only one working frequence. If we change L1 or C1 or C2 or all these together I'm not sure that the "phenomenon" is detectable. However, it is always useful to experiment with new solutions.

Best Regards

Hi Franco Can you tell me what is the inductance value for your L1?

Yes I agree with that you said

Hi Nicolas
I'm not in Italy, but I remember that inductance is less than 1 microhenry, I think that the value is not critic, surely 3 turns are ok.
Regards

Ok thanks Franco
good tavel and return

Hi Nicolas
I return tomorrow, about 400 km of travel. What is your city? My is near Imperia.
Regards

Welcome franco
My city is Lamezia Terme Regione Catanzaro
But now not live there. me too.

-------------
Benvenuti franco
La mia cittÃ* è Lamezia Terme Regione Catanzaro
Ma ora non vivere lì. anch'io :lol::D

two type of selector
 

Here is for adapt to PDK-2.1 ,two diferent selector according the problems found in each country :


Its not difficult to build this simple selector ,need only to cut the original 6n8 cap. that is in paralel with the RX receptor coil,and use the cuted legs of the cap. to solder the SELECTOR wires.
In the photos i show the place where 6n8 was removed to give place for selector wires.
Any question cotact my email or send PM

Attachment 18683

Attachment 18684

Attachment 18685

Hi All
this is my Christmas gift :) it's another version of my Lrl more sensitive but less difficult to build. The oscillation comes from a CD4046 and we measure the phase change between the VCO and the output of the amplifier stage (TR2-TR3 and TR4). As antenna you can use a stylus or (better for me) a coil antenna. The capacitors C8 and C9 are connected in series for a single 0.5 pF capacitor (I think difficult to find). The power stage is the same of the other Lrl. In this simplified version there is only a led but is better to use more leds, I use a LM3914 to drive ten leds. The frequency is in the range 2.8 - 3.0 Mhz with the P1 cursor close to + 12V. Also the P2 cursor is close to positive and this means a small signal to input amplifier stage.

Best Regards

I forgot L1, it's the same of the other Lrl, that's 3 turns air core, 10 mm diameter.

:frown: I forgot also C18, it's 4.7 nF.

Hi FrancoItaly!
You're the real Santa Claus!
Thank you very much!
Merry Christmas FrancoItaly!
Regards and All the Best!
Sneshko

Hi Franco, thanks for the new schematic.
Does it has more detecting distance or it is the same????

My wishes for Merry Christmas and Happy New Year:)

Hi Geo
I tested this Lrl only near my home with an unknow target and the signal is 50% more than the other Lrl and now I'm in Switzerland and I decided to post the new schemas. As I said this circuit is an amplifier and not an oscillator and it's more easy to build. It's also possible to change the frequency and the amplitude of the signal. I'll do other tests when I will return to Italy. It's also possible to change the turns in coil antenna for better results. Perhaps with this Lrl You'll have good results, indeed it seems strange to me that in Greece there is no "phenomenon".
Best wishes to you and family

Hi Franco.
Again at Switzerland!!!!!:lol:
It is very good news that you catch the phenomenon with stronger signal, so you will locate the object from longer distance. Now i "play" with 3 projects, when i"ll finish with them i"ll construct your lrl so to see what is happening this time at my field area. Did you see any problem with high moisture and low temperature???

Regards:)

Hi Geo
In Switzerland I have more time to think about the "phenomenon" and ... other stuff:lol:. I haven't noticed any change with high moisture and low temperature, but in my country the temperature is never too low. I am very pleased by the fact that with this Lrl there is no "compass effect".
Regards