Lrl from Italy

[Inna]

Originally Posted by omar

The bc547c / bc548c / bc549c transistors have a gain in the lower limits of 420hfe.
The circuit needs to adjust and reduce the value of the resistance R12 to achieve the required gain with it. As our friend Franco said.

Note it has a wider bandwidth than the bc183c

I'm sorry Omar, but the 548C has hfe gain from 420 to 800, the ones I selected for my circuit, I tested them with a Chinese multi-tester and they all have hfe values ​​above 500. Do you think it's too low? Better if I replace them or by intervening on the resistors, can I still get a good result?

[FrancoItaly]

Originally Posted by Inna

I'm sorry Omar, but the 548C has hfe gain from 420 to 800, the ones I selected for my circuit, I tested them with a Chinese multi-tester and they all have hfe values ​​above 500. Do you think it's too low? Better if I replace them or by intervening on the resistors, can I still get a good result?

A gain of 500 is sufficient, by the way higher values are difficult to obtain.

[Inna]

Originally Posted by FrancoItaly

A gain of 500 is sufficient, by the way higher values are difficult to obtain.

Thanks mr. Franco, so if I change the values ​​of r10 and r11 to 470 ohms, I can use the bc548cs, increasing the gain a bit.... Is that right?

[Inna]

Sorry, errata corrige: r10 and r 12...

[omar]

Originally Posted by Inna

Thanks mr. Franco, so if I change the values ​​of r10 and r11 to 470 ohms, I can use the bc548cs, increasing the gain a bit.... Is that right?

Back up. Put in variable resistors to increase the gain when you need it. So as not to disassemble and install and damage the circuit. I know that the device must sense the magnetic north and the sky, then it is ready for field work.

[omar]

note. Variable rectifiers are set only once. When the desired sensitivity is reached. Leave the third leg of the variable resistance in the air means not connected.

In the end, I extend my thanks and gratitude to our friend Franco for supporting the topic and helping the members.


https://top4top.io/downloadf-2561g1si50-rar.html

[Inna]

Well done. When you get the right gain value, if possible, you can replace the trimmers with fixed resistors with a value close to the value measured between the extreme pin and the central pin which are connected to the pcb.

[FrancoItaly]

Originally Posted by Inna

Thanks mr. Franco, so if I change the values ​​of r10 and r11 to 470 ohms, I can use the bc548cs, increasing the gain a bit.... Is that right?

Yes

[abdou2014]

I made a modification of franco lrl this week, and I have very strange results ???
no reaction to electrical or magnetic interference, it only reacts to the white LED lamp, and the sound is very looklike to a magnetometer ??

[Inna]

Please, can anyone tell me if this coil (L1) is correct? Is the number of turns right as seen in the picture? I add that the diameter is 1 cm, while the section of the wire is 0.7 mm. Do I necessarily have to use the 1 mm wire? Thank you.

[FrancoItaly]

The coil is perfect, however it is not critical.

[Inna]

Good morning to everyone. Sorry if I ask questions that may have already been answered in the past. But I saw on a YouTube video that someone put a digital display voltmeter on this device. I wanted to know what its function could be and the difference, from the 3-leds monitor, and if it a good thing to mount on. And possibly where it should be connected. Maybe the (-) on ground and the (+) on TR5's emitter output? Thank you.

[Inna]

To be clear: in this point?

[FrancoItaly]

In my opinion 3 leds are sufficient, however a digital display voltmeter must be connected to the output of the first LM358 which is the DC amplifier stage.

[Inna]

Originally Posted by FrancoItaly

In my opinion 3 leds are sufficient, however a digital display voltmeter must be connected to the output of the first LM358 which is the DC amplifier stage.

Good morning Mr. Franco, please could you tell me the right point to connect the display on first LM358?
Many thanks.

[FrancoItaly]

Digital meter at IC1A output and ground. However, the stage relating to the buzzer and the first LED is necessary. I attach a display stage easier to adjust the threshold.

[Inna]

Because I made the last Omar's pcb, I should ask if It's the blue point in the attached scheme, the right point to connect the (+) positive input of the multimeter?

[FrancoItaly]

Yes it's correct.

[Inna]

Hello, I would like to ask if it was possible to power this device with a single 9V battery and then a 12V regulated step-up module, thus eliminating the 7812. Has anyone already tried it? Could it work like this? Thanks.

[FrancoItaly]

I do not recommend this solution, as these step-up modules work via an internal oscillator which could interfere with the sensor stage.

[Inna]

Good advice. Thanks Mr. Franco.

[Inna]

Hi Mr. Franco,
I'm talking to you because lately this forum seems to be little frequented. Too bad because it's so interesting, but I also understand that I'm the last to arrive and I missed the best...
I still have to finish building your LRL and for an inexperienced one like me, I already foresee many problems in the calibration.
However I'm always wondering if it was possible to improve the aspect concerning the power supply of the device and I asked and proposed if, in order not to affect the circuit, to be able to use a 12V, 1.2Ah lead battery + the step-up module or possibly a diode booster circuit, to raise the voltage to 16/18 Volt.
But this time, these elements will have to be released from the body of the LRL, ie distant and connected for example to the handle, through a simple cable.
Maybe it could improve stability and battery work time. Sorry if I ask many questions.
Thanks for your help, always in time.

[FrancoItaly]

Yes, it's true, at the moment the forum is not very popular, but there are few topics to develop, however lrl from Italy has reached almost one million views, even in many years of activity. The lrl is not simple to implement, where there is a large amplification at relatively high frequencies there are always problems. The only pcb I made and made available is the sensor stage , and I recommended to use a double sided pcb, or shield the bottom with aluminum foil or another unetched pcb. The first lrl had no oscillator but simply self-oscillated, it was a bug detector that I found worked like the lrl. About power I recommend you again to use the original system with two 9V batteries, over all the consumption is about 20mA.

[Inna]

Yes, Mr. Franco, I will leave the power supply as the original. I'm doing a very particular montage, I used a plastic container that covered a bottle of perfume. I will connect the handle to the negative on the outside, to have contact with the hands and I will put the batteries in the hollow handle. As for the pcb, I chose to process the last one posted by Omar and I've already shielded it with a sandwich made up of a layer of aluminum foil below and a layer of cardboard above, so it will be well insulated from contact with the pcb tracks. But the aluminum is also connected to the negative like the handle. I also built the antenna amplifier that was suggested separately, I provided the 40 pF variable capacitor (the only one value now I have) at the antenna input, so as I wrote, it won't be easy to calibrate everything, there are many variables. I'm afraid I have to ask for his help often. However for now I'm going ahead with the construction, when I can due to lack of time. Thank you.

[omar]

A person photographed and detected (iron grille) inside a concrete wall in infrared. It seems that metals, especially those with heavy atoms, are radioactive when they are under pressure.


If you photograph a large amount of gold, such as a goldsmith's shop, with a mobile camera, with the flash on. You will clearly see that gold sends low-frequency electromagnetic pulses in the form of circular packages. It is detected by photoinduction. The phenomenon, and God knows best, exists. But where is the right way? We do not know . Thanks