Selectivity with LM567
 

I present to you this important IC in the field of remote sensing, which is characterized by selectivity in detection, as you can specify the central frequency you want to search for, and it will detect that signal for you if it is present in the field. While rejecting other unwanted signals. Despite its simple appearance, the circuit is complex and consists of more than 62 transistors.

For full information and how to use, see the data sheet.

With a note, it is used in detecting radio frequencies, light, infrared, sound, and radar modifications. It depends on the added sensor circuit.

Note: You must study the data sheet well to be able to use it and work correctly.



https://www.homemade-circuits.com/lm...-features-and/





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This is a good option. But you will have to look for high-quality microcircuits. Personally, I found a spread of 20 hertz at a frequency of 10 kHz with a spread from the desired frequency, and the lower the transmission frequency, the greater the error. Or you will have to add more nodes to the circuit, as is done in the Amostra filter.

Hello my friend Bahoum, and thank you for this nice intervention.

the resonance frequency in nature was calculated, it was found that the frequency of the basic metal of gold is 37 Hz and that of the silver metal is 87 Hz. These values ​​vary according to the strength of the earth?s field in your area. We try to help in this area as much as possible while keeping things simple. The question that arises and which many disagree about is what type of signal we are looking for.

* Chapter One: If the signal is electrical, and this is what I am convinced of, it resembles a spark, a cigarette lighter, or lightning in the form of pulses with very small amplitudes that can be detected using germanium or Schottky detector diodes with a demodulation feature and extracting the low frequency of the pulse.

* Chapter Two: There are those who claim the ability of infrared rays to detect. If we use sunlight as an infrared transmitter and monitor its reflection from the Earth's surface and the magnitude of the pulsation, this may be a good solution in determining the center.


$$ My important question that needs to be answered is if a radio frequency is directed at a metal surface, is it reflected with a modified imprint of the metal or is it reflected without modification?

Thanks

I don?t know the answer to the main question and the frequency is different for everyone. I answered about the LM 567 microcircuit on which the filter is proposed. The chip is not bad!!!! Then only checks and long studies of this active filter. And then someone will be lucky or give a hint. I dug that granite myself. Once again the chip is not bad!!!!!!

lm567 calculator
 

general information
 

* When the radio frequency is reflected from the surface of the metal, it will carry with it the resonance of the metal, They create an amplitude and phase jump at each resonant frequency of the returned signal which is a technique used in radar.

* The resonance signal for metals is an electrical signal in the megahertz and gigahertz range.

* Gold responds well to radio frequencies because of its high conductivity and does not corrode like other metals in the soil. The high density of gold makes it interact greatly with radio frequencies and has a significant effect on the radio frequencies reflected from its surface. It reflects the radio signal well

* Metal detector radar uses radio frequencies to penetrate the ground to accurately detect metals. The best medium frequency range. This range is balanced with penetrating power and accuracy.

* Schottkine diodes are better than germanium for detecting weak electrical signals. ( Pin diodes) are specialized in very small capacitances and are used when high-sensitivity detection characteristics are needed.

* Photoelectric technology uses light to detect metal resonances by measuring changes in light


$ The source of this information is artificial intelligence

Hi Omar!
this description is very interesting and I think very accurate!

Many years ago (maybe 20) i constructed an electronic dowsing rod using the LM567.I found the schematic :cool:

information
 

Hello friends,

relying on the ringing of natural metal for detection, I think is not enough. It may be suitable for large sizes only. Due to the presence of influential external factors that control the strength of the corona and change the values, such as your proximity and distance from the Earth?s magnetic poles, the movement of the Moon around the Earth and its effect on the strength of the Earth?s magnetic field and climate, heat gives the electrons kinetic energy and makes them active and spread over the Earth?s surface because they are mostly concentrated on the Earth?s surface, so the air is a natural insulator for them.


$ The Earth?s conductivity affects the transmission of the beam to the Earth?s surface. Several haloes may form for the object, and they may deviate from the center of the target a lot. External radio frequencies are also effective. Large mineral masses (mineral rocks) have an effect. Therefore, there will be no stability for the aura with its frequency values, activity, and location. Luck will play a big role in success. When you are at the right time and the right place.


$ This information is based on my personal follow-ups. I archive it here in the forum for others to benefit.



I think my friend Geography added a better sensor circuit.



Illustrative image only.


https://k.top4top.io/p_3035znr6p0.png

Hello omar!
You have made this schematic? I think with an additional circuit it will be a very good general receiver.

ideas
 

Hello friend Kostas 87.

Don't forget, this type of circuit has become more selective with the LM567. We left out randomness. The detection range is approximately (19 Hz to 6 kHz) .

I will put together an infrared sensor circuit to illustrate the idea of ​​the variety that can be achieved while maintaining selectivity. With a bandwidth between approximately ( 1% - 25% ) .
]




Note:

The diagrams that I design have not been confirmed to work with the 567 because the simulation program I use does not contain the 567, so we recommend trying the circuit on a breadboard first.




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Hi Omar

Personally i had made an IR receiver trying to demodulate any possible useful frequency that might be imposed on it. I tried for demodulating frequencies in the KHz range (strong signals) that exist in the area but the result was very dissapointing. The IR field behaved like it is a total dc field with not any short of fluctuations. Despite the high amplification stage i never got any response.



I think that you should include in your research the diamagnetic property of the target.

Opinions
 

I don't know

But if the resonance effect is a capacitive effect, the signal will not appear with high frequencies of infrared radiation. It will be lost within the carrier signal,
so it is suitable for measurement only based on the intensity of reflection

. ( Capacitive modulation is used for intermediate frequencies (AM)) . This may be an explanation that they prefer to use 250 kHz receiving resonance circuits in long-range metal detectors. Coincidentally, this frequency is also used to detect electrical signals.


Magnetism cannot be relied upon to detect precious metals because they are non-magnetic metals. Most suitable for ferrous metals.



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Hi Omar
Diamagnetic material means that opposes to any magnetic field change. So it also induces currents but in a direction so to oppose the incident magnetic field change. It is like the transformer effect. So magnetism and diamagnetism are the two mirror sides of the same coin. :)