AV multiband VLF receiver

[mustefa ubram]

Excellent wm6 for schematic
wm6 and j-p
I have no experience with this frequency range.and i have question
How to measure the resonance frequency of the use of metals in the circuit when the transmitter?
Whether the transmitter of the loop antenna to generate frequency vlf is right?
Vlf range of frequencies to transmit and detect what is right??(3kh-4kh-5kh.....30kh)
Transmitter frequency to the ground after hitting the metal out of the ground in what form?
The receiver can reveal how the radial wave vlf?

[J_Player]

Originally Posted by mustefa ubram

Excellent wm6 for schematic
wm6 and j-p
I have no experience with this frequency range.and i have question
How to measure the resonance frequency of the use of metals in the circuit when the transmitter?
Whether the transmitter of the loop antenna to generate frequency vlf is right?
Vlf range of frequencies to transmit and detect what is right??(3kh-4kh-5kh.....30kh)
Transmitter frequency to the ground after hitting the metal out of the ground in what form?
The receiver can reveal how the radial wave vlf?

I do not believe any frequency that you transmit will allow you to detect buried metal with this receiver.
But I may be wrong.
Other experimenters use any frequency between 70 KHz to 150 KHz

Best wishes,
J_P

[okantex]

J_Player ,

do you think that emfad is narrow band reciver, yes it has a tunner , but it's range is too much.when this circuits bands are considered to emfad it is enough narrow
look , with wide band ,you wont able to recieve more frequencies at each listening.you will generally have one frequency ,but when you have more frequency at same time , you will always tune your led to powerfull station's upper noise level as PDK does fro VHF waves. it will be good to add multiturn pot as threshold adjustment.

what do you think of it.
but still this receiver has less tr than emfad.

[J_Player]

Originally Posted by okantex

J_Player ,

do you think that emfad is narrow band reciver, yes it has a tunner , but it's range is too much.when this circuits bands are considered to emfad it is enough narrow
look , with wide band ,you wont able to recieve more frequencies at each listening.you will generally have one frequency ,but when you have more frequency at same time , you will always tune your led to powerfull station's upper noise level as PDK does fro VHF waves. it will be good to add multiturn pot as threshold adjustment.

what do you think of it.
but still this receiver has less tr than emfad.

I think this circuit is a good toy to experiment with to learn the directional properties of ferrite antennas.
I do not think it is a narrow band tuner.
I think if you want a narrow band tuner, then you should select the narrow band that you want to investigate, and then build a new design narrow band tuner to listen for your frequency.

Best wishes,
J_P

[FrancoItaly]

Hi All

As Esteban said also a passive receiver may be a sensitive lrl, then there is no need for trasmitting any wave, it's the signal that comes from buried target that goes away. A stimulus or trasmitter signal can serve only for a reference signal, as the signal from buried target it has not a precise frequency, somehow it works on different forms of signals, magnetic, electromagnetic, infrared.

Best Regards

[Qiaozhi]

Originally Posted by FrancoItaly

Hi All

As Esteban said also a passive receiver may be a sensitive lrl, then there is no need for trasmitting any wave, it's the signal that comes from buried target that goes away. A stimulus or trasmitter signal can serve only for a reference signal, as the signal from buried target it has not a precise frequency, somehow it works on different forms of signals, magnetic, electromagnetic, infrared.

Best Regards

Has anyone tried to build the TOTeM pistol detector from "Inside the METAL DETECTOR"?

It is intended as an experimental platform for investigating LRL technology, and has both passive and active modes; plus audible (beeper) and visual (LED & meter) outputs. The beeper can also be turned off for clandestine detecting.

There is no PCB for this design, as it was built on stripboard. However, anyone is welcome to design one and post it here.

[FrancoItaly]

Hi All

I don't know the TOTeM pistol detector but in my experience only a passive receiver with the TX stage off,it doesn't have enough sensitivity, it must amplify some unknow signal of unknow frequency. My most recent lrl uses a high gain rf stage in self oscillating condition: it's a passive receiver, it doesn't trasmit any signal but it's very sensitive to external influence. The TX signal dramatically reduces the signal from buried target but the lrl it remain sensitive to Sky/compass effect.



Best Regards

[mustefa ubram]

Originally Posted by J_Player

I do not believe any frequency that you transmit will allow you to detect buried metal with this receiver.
But I may be wrong.
Other experimenters use any frequency between 70 KHz to 150 KHz

Best wishes,
J_P

Which part of the circuit can absorb from the environment, much frequency tables?
Specifically?
Please show on the schematic

[J_Player]

Originally Posted by mustefa ubram

Which part of the circuit can absorb from the environment, much frequency tables?
Specifically?
Please show on the schematic

Hi mustefa ubram,
The only parts of the circuit that can absorb RF from the environment are shown below.
But also, other components can absorb from the environment in very small amounts.

Best wishes,
J_P

[mustefa ubram]

hi
I've read on this system.I believe that these systems requires a filter.To match with the transmitter.Because there are a lot of disturbing signals in the signal and is absorbed by the ferrite The system reacts to these signals interfere.And can be difficult to detect transmitter signals.
I believe there is a filter that allows the recipient to respond only to our own frequencies.
In the general case requires the system to a point that is specified in the Filter..
What do you think?

[mustefa ubram]

Originally Posted by mustefa ubram

hi
I've read on this system.I believe that these systems requires a filter.To match with the transmitter.Because there are a lot of disturbing signals in the signal and is absorbed by the ferrite The system reacts to these signals interfere.And can be difficult to detect transmitter signals.
I believe there is a filter that allows the recipient to respond only to our own frequencies.
In the general case requires the system to a point that is specified in the Filter..
What do you think?

Anyone disagree?

[WM6]

Originally Posted by mustefa ubram

Anyone disagree?

Which filter do you mean?

This is multi-band receiver with selective tuned band, which is some sort of filtering.

You do not need filter here, or you need multi-filter (not worth all efforts). But you need good sine transmitter.

[J_Player]

Originally Posted by WM6

Which filter do you mean?

This is multi-band receiver with selective tuned band, which is some sort of filtering.

You do not need filter here, or you need multi-filter (not worth all efforts). But you need good sine transmitter.

It appears that the readers of this circuit do not understand it is simply a toy to experiment with and learn the directional properties of ferrite antennas.
But they want a narrow band tuner. Why? Who knows?

I think if they want a narrow band tuner, then they should select the narrow band that they want to investigate, and then build a new design narrow band tuner to listen for the frequency they want to hear. This circuit is a waste of time to modify to become a narrow band receiver.

Maybe we need a new circuit that uses a crystal clock with digital divider and PLL to select desired frequency, then a narrow band adjustable notch filter to find the exact frequency that the receiver will tune to. Then we should also have a bank of capacitors and matched ferrites for each band, which can be adjusted 20-30% within the band by the digital logic and notch filters in combination with adjustable capacitors.
Maybe 20 frequency bands would be good to start with.
Then we can add more ferrite-capacitor antennas to get more frequency bands when we find that none of the 20 initial bands find treasure.

What do you think?
Are we ready for a new circuit design?


Best Wishes,
J_P

[mustefa ubram]

Originally Posted by WM6

Which filter do you mean?

This is multi-band receiver with selective tuned band, which is some sort of filtering.

You do not need filter here, or you need multi-filter (not worth all efforts). But you need good sine transmitter.

If you select any of the bands is not heard no noise except for the frequency of the playoffs?
Filtering to eliminate noises that disturb land.

[mustefa ubram]

Originally Posted by J_Player

It appears that the readers of this circuit do not understand it is simply a toy to experiment with and learn the directional properties of ferrite antennas.
But they want a narrow band tuner. Why? Who knows?

I think if they want a narrow band tuner, then they should select the narrow band that they want to investigate, and then build a new design narrow band tuner to listen for the frequency they want to hear. This circuit is a waste of time to modify to become a narrow band receiver.

Maybe we need a new circuit that uses a crystal clock with digital divider and PLL to select desired frequency, then a narrow band adjustable notch filter to find the exact frequency that the receiver will tune to. Then we should also have a bank of capacitors and matched ferrites for each band, which can be adjusted 20-30% within the band by the digital logic and notch filters in combination with adjustable capacitors.
Maybe 20 frequency bands would be good to start with.
Then we can add more ferrite-capacitor antennas to get more frequency bands when we find that none of the 20 initial bands find treasure.

What do you think?
Are we ready for a new circuit design?


Best Wishes,
J_P

Not need more bands Treasure Hunt.
We need a powerful transmitter and a wrist receiver that the transmitter.For example, if the transmitter sends a frequency 5 kHz The receiver will only receive 5 kHz frequency And not heard another noise.
A Question:
Can reveal whether the recipient New metal in the soil?

[J_Player]

Originally Posted by mustefa ubram

Not need more bands Treasure Hunt.
We need a powerful transmitter and a wrist receiver that the transmitter.For example, if the transmitter sends a frequency 5 kHz The receiver will only receive 5 kHz frequency And not heard another noise.
A Question:
Can reveal whether the recipient New metal in the soil?

I tell again one final time:

This circuit is not designed to receive only one frequency with no noise.
It is designed only for a toy to demonstrate the directional properties of the ferrite receiver.
It is a very simple circuit which is not even worth the trouble to add a filter circuit.

Filters are used for more sophisticated circuits.
If you want to add a filter, you must first know what frequencies you want the filter to remove, and what exact frequencies you want the filter to allow to pass through so you can receive them.
Since this is a multiband receiver, you cannot use a single filter.
you must build at least 5 separate filters, one for each band.
Then these filters must switch to a different filter when you change the position of SW2.
But that is only for a simple filter at the preamp where you believe it is needed.
You are wrong.
You need more filtering than a simple filter at the preamp if you want to remove the noise from this circuit and receive a clear signal.
You must add different filters at different stages to remove the noise signals you do not want.
Also the amplifiers must be low-noise before you can hope to get a clear signal. These are simple signal transistors - not special low noise amplifiers!
For proper filtering, each filter must be designed to remove a specific kind of noise at the different amplifier stages.
Each of these filters is made with specially calculated component values to remove the frequency range which you want to remove.
Also you must consider the antennas which you are using.
With the design I see, the noise picked up from the magnetic antenna is several times more noise than an electric field antenna, simply because it is several times more sensitive than the electric field antenna at VLF frequencies.
The filtering must be designed with this in mind.

If you want the filter to allow only a narrow band to pass through when you tune to various different frequencies, then the filters become very expensive. And they cost more than all of the parts you see in this receiver. For this reason, you are better to begin with a good VLF receiver that was intended to receive a clear VLF signal instead of a toy circuit that was designed to experiment and learn about the directional properties of a ferrite antenna.

If you think that you can make this toy receiver reject all noise and receive only the frequency which you want, by simply inserting a filter at the preamp, then you make a mistake.
The idea to add a preamp filter and believe it will remove all the noise is a mistake.
And it is a stupid way to waste time with electronic designing that is guaranteed to produce bad results.
But if you really believe that inserting a preamp filter will make the noise stop in this simple receiver, then see the image below that you can put in the place where you think a filter is needed.
Since you don't know any specific frequencies you want to remove, this is a simple low pass filter.
I think it will not remove all noises and give a clear signal, but you can try it.

A Question:
Can reveal whether the recipient New metal in the soil?
Answer: Geologists can find metal in the ground with a VLF receiver.
They usually tune to a distant VLF transmitter maybe 1000 km distance or more.
Sometimes they tune to a transmitter which they bring to the place where they want to search if there is no government transmitter sending a signal.
Then they can locate a metal tank in the ground, or a car that is buried in the ground.
They cannot locate a gold coin in the ground with their VLF receiver.

Best Wishes,
J_P

[WM6]

Originally Posted by J_Player

What do you think?
Are we ready for a new circuit design?

Agree with you.
We are still in life and this fact promise new circuit design too.

[WM6]

Originally Posted by mustefa ubram

We need a powerful transmitter and a wrist receiver that the transmitter.For example, if the transmitter sends a frequency 5 kHz The receiver will only receive 5 kHz frequency And not heard another noise.
A Question:
Can reveal whether the recipient New metal in the soil?

You do not need powerful TX (no benefit from power here), but you need good sine wave TX and noise will not be big problem.

As J_P explain this receiver is designed to experiment and play around with directive (ferrite antenna) receiver.

There are theoretical possibilities to detect reflected wave from very big metal surfaces no matter if it is New metal or Old metal.

But you do not expect to detect on remote small targets as one coin alone (buried or in air). Such intention already encroaches sphere of dowsing and not simple electronic design like this.

[J_Player]

Originally Posted by WM6

You do not need powerful TX (no benefit from power here), but you need good sine wave TX and noise will not be big problem.

As J_P explain this receiver is designed to experiment and play around with directive (ferrite antenna) receiver.

There are theoretical possibilities to detect reflected wave from very big metal surfaces no matter if it is New metal or Old metal.

But you do not expect to detect on remote small targets as one coin alone (buried or in air). Such intention already encroaches sphere of dowsing and not simple electronic design like this.

When a geologist detects metal in the ground, he is measuring the magnetic properties of the ground. It is the same as using a VLF metal detector to measure the magnetic properties of the ground. But the geologist will use the VLF waves in a different way than a treasure hunter uses on his VLF detector. A treasure hunter will take measures to remove the effects of ground mineralization and look only for metal things which are in the near proximity of his transmitter. For a geologist, he is looking for ground mineralization, so he does not cancel it. He moves the RX loop to make a survey of all the ground, and he records his readings. This can tell him how the ground mineralization changes at different parts of the land. His VLF receiver antenna will certainly tell him if he finds a buried metal tank or car, because he is measuring the induced magnetic field which the transmitter induces in conductive ground below the surface. A buried metal tank or car will show an anomaly because it is more conductive than the surrounding ground. For the geologist, the buried metal trash is considered noise which he ignores when trying to determine what rock formations are under the ground. The things which the geologist is finding are conductive soils, which give a stronger signal, and especially soils which have magnetite or hematite deposits, and other mineralized rocks.

For treasure hunting, the geologist methods can help to locate ore deposits, but not small metal objects.
The treasure hunting techniques for long range VLF detecting require building simple VLF transmitters and receivers, then performing secret tuning to find the elusive treasure signal.
Since these are secret tuning methods, and the treasure signal is also a secret, no geologist or engineer knows anything about the secret gold signal or methods to tune a simple VLF transmitter and receiver to find a gold signal.
You must contact a builder of secret treasure finding locators if you want to know the secret of tuning a VLF transmitter and receiver to find the secret gold signal.
Morgan and Geo are the only people who I see posting in the forum that their secret gold-finding treasure locators are really working, and Morgan is even showing photos of the treasure they find.
You must ask Morgan or Geo how to build your VLF transmitter and receiver to find the elusive gold signal.
They are nice people. I am sure they will help you to build a VLF transmitter and receiver that really works to find treasure for you.


Best Wishes,
J_P

[FrancoItaly]

Hi All
no necessity of VLF trasmitter, the trasmitter kills the phenomenon but non the compass\sky effect. A simple RF amplifier in self oscillating mode it can sense the phenomenon, but to do a stable oscillating amplifier it's difficult, you must have a no saturated output.

Best Regards

[J_Player]

Originally Posted by FrancoItaly

Hi All
no necessity of VLF trasmitter, the trasmitter kills the phenomenon but non the compass\sky effect. A simple RF amplifier in self oscillating mode it can sense the phenomenon, but to do a stable oscillating amplifier it's difficult, you must have a no saturated output.

Best Regards

Hi FrancoItaly,
What phenomenon does the transmitter kill?


Best Wishes,
J_P

[FrancoItaly]

Hi J _P

Long time buried metals emit something that's perturbs the E-field or the B-field of the earth, this is the "phenomenon".

Best Regards

[mustefa ubram]

tank you wm6 j-p and other
What solution do you recommendFor smaller objects ?

[WM6]

Originally Posted by mustefa ubram

What solution do you recommend For smaller objects ?

Regular metal detector for now.

What of use, if you can "locate small targets kilometres away" by using LRL, if, at the end of the day, you need a metal detector to prove, when you locate something or not?

And digging holes till 50cm of depth using MD can be far enough for recreational purposes.

[mustefa ubram]

A circuit for detecting electromagnetic: