A VLF RECEIVER

[Alex]

Anybody has the time and patience to make a PCB from this
vlf receiver schematics? .I have a small idea to use it with other device
as a LRL .R4 is 22M and I cannot find so big value so I have to use 5 resistors in place...
Any help welcome.
thanks

Alex

[Alex]

here the schematic:

[Fred]

Hi,

this receiver has no tuning circuit, i´t s just a filtered amplfeir ?
So i guess you must connect it to a computer to "see" signals...
regards,
Fred.

[Alex]

Yes this is only filtering and amplify the signal up to 20 kHz .Is good for gold
and silver frequency.Of course you need a laptop to see the signal..also you can listen on the phone...Need other device too.
I have to make first this one after I will try and do experience outside..

[Fred]

Originally Posted by Alex

Yes this is only filtering and amplify the signal up to 20 kHz .Is good for gold
and silver frequency.Of course you need a laptop to see the signal..also you can listen on the phone...Need other device too.
I have to make first this one after I will try and do experience outside..

Hi alex,

From 0 to 20khz you are going to pick up plenty of signals, natural and not-so-natural , but i don´t see how you can detect any metal with it , and less discriminate between them.
anyway it could be an interesting experimentto to go around with a laptop and see what happens.If you detect a multi-thousand tons moving and radioactive metallic item, don´t be afraid it´s just a submarine.
Good luck,
Regards,
Fred.

[Alex]

Is ok.I ask something and until now you didn't answer me. I need the PCB. .I know I can hear a submarin even a angel .A good one .
You are a guru not me, so if you want you can add a fine tuning at this schematic for 5Khz and 8.7khz.
This can be your help in this project.Wait until the end....
I told you there is another device in this but we will talk later .First step build this ,make the improvment ..and see.

[Fred]

Originally Posted by Alex

Is ok.I ask something and until now you didn't answer me. I need the PCB. .I know I can hear a submarin even a angel .A good one .
You are a guru not me, so if you want you can add a fine tuning at this schematic for 5Khz and 8.7khz.
This can be your help in this project.Wait until the end....
I told you there is another device in this but we will talk later .First step build this ,make the improvment ..and see.

Hi Alex,
To be a guru you only need to talk a lot, this doesn´t mean you´re good at it
Anyway i will try to make the PCB, i will post it a soon as i can.Switches and leds will be out of PCB.For R4 (2X 4M7) + (2X 6M should be OK.
I assume L1 and L2 are 1/2W size or so.I don´t know exact pinout of F1(fet), but that should not be a problem.
regards,
Fred.

[Alex]

Hi Fred

Thanks for your help.I need to add something before to start do the pcb.You have to know this:
The FET Gate resistor R4 is the main component that determines how much of the voltage
captured by the antenna will actually be amplified in the receiver. Stated a different way, R4 determines the ultimate sensitivity of the receiver. The value chosen for R4 (22MΩ) is a compromise value considering costs, component availability, circuit board layout and receiver sensitivity. For maximum sensitivity a value >100 MΩ should have been chosen.
If you think you can make R4 BIGGER do it for more sensitivity...
thanks a lot
Good work.
Alex

[Fred]

Hi Alex,

You can find here the PCB.
IT shoudl be re-verified, please let me know if there is mistakes or improvements.
Hope the shape of PCB is OK for you
Highter definition files zipped .
Happy building,
Regards,
Fred.

[Alex]

Really thanks Fred.
Yes the shape is perfect what we need.I will control the pcb tonight.
I want just to thanks you again you did in so short time.
Greatings
Alex

[Alex]

Do you think is it possible to have a series of led at the output of
signal so you can have a idea when it became stronger ...or you are closer to
target?.
THANKS

[Fred]

Hi,
Here is a PCB for a sensitive vu-meter that use led row.
I have built it, i works fine.
Hope it helps!
regards,
Fred.

[Alex]

I really appreciate what you done ,so fast and nice work.Yes the leds are good.I will try to make it this days.
I don't know in your country but here is a Passover tomorow ,so I send you my best wishes anyway.
Have a nice weekend.
Thanks again
Alex

[Fred]

Hi Alex,

Yes ,here too, so we have 3 days in a row
Good luck with your project , and best wishes.
Regards,
Fred.

[Dell Winders]

For what it is worth, it is pleasing to see you cooperating and working together in friendship. With my best wishes. Dell

[Fred]

Originally Posted by Dell Winders

For what it is worth, it is pleasing to see you cooperating and working together in friendship. With my best wishes. Dell

Thanks Dell,
Apreciated.
Regards,
Fred.

[Fred]

An interesting circuit...

Regards,
Fred.

[Qiaozhi]

Originally Posted by Fred

An interesting circuit...

Regards,
Fred.

I hope the antenna is not mounted on a long pole, otherwise you could get more than you bargained for!

[humhum]

Borrowing:

Gold has an NMR frequency of 1.754MHz relative to hydrogen @ 100MHz, which establishes the test magnetic field at about 2.35T. The Earth has an average field of about 50uT, so buried gold would have an NMR frequency of about 37Hz. Someone please correct me if I'm wrong.

[Alex]

Fred in your Vu meter there are 3 components with name missing.Please add the name so we can make it.Thanks

DELL thanks for your participation here.Nice from you.

QIAOZHI .I select this kind of receiver for you use a telescopic antenna up
to 6 foot so is light and easy to cary..There are many models but usualy they
have heavy antenna ..

HUMHUM.
I can't aswer your question .My intention is to ,,cach'' the molecular
frequency of gold and silver and Carl said is 5khz and 8,7 khz.
This property is used also in medicine to detect presence of parasites ,bugs or diseases in human body .In this way maybe we can detect not only old
buried gold or silver but also a new one.
Thanks all.

[Fred]

Hi Alex,
Sorry,here you go.
Also includes a different PCB.This one use individual leds.
Regards,
Fred.

[Max]

Originally Posted by Qiaozhi

I hope the antenna is not mounted on a long pole, otherwise you could get more than you bargained for!

I saw an old project for a storm detector in old "modern" mechanics maybe... but the risks are about the same!

Like the X-ray and laser projects... it seems good to toast something... or someone!

Kind regards,
Max

[Max]

Originally Posted by humhum

Borrowing:

Gold has an NMR frequency of 1.754MHz relative to hydrogen @ 100MHz, which establishes the test magnetic field at about 2.35T. The Earth has an average field of about 50uT, so buried gold would have an NMR frequency of about 37Hz. Someone please correct me if I'm wrong.

Hi,
well maybe calculation is good... I didn't check it... but NMR data collecting is possible when the target is inside the coil... not outside...

The problem is that even a big gold target will generate so small decaying Larmor compliant precession signal that you will not be able to "read" with a coil from far away few distance.

You need a static magnetic field (in your idea it's the Earth's magnetic field you said) and a perturbing magnetic field orthogonal to the first.

You need them PERFECTLY orthogonal, you need to apply well known field intensity to align particles (nuclei having a magnetic moment if you really want do NMR) and then shut down and let them precess at required frequency.

Then you read the signal by a e.g. an rx coil... or just measure e.g. absorbtion of energy at this particular frequency (nmr related loss).

A thing you must consider is the energy required to do so with macroscopic objects is really enormous and you will probably need some 1-10 tesla induction system (using superconductors and "small" portable power source I think... for portable unit .... say you need maybe from 10KW to 1MW power depending on conditions... just to supply the coil... then a dynamic platform that will align coil orthogonal to soil... uhm seems science fiction now....? )

Seems not an easy project... so good luck!

Kind regards,
Max

[Max]

Originally Posted by Alex

Fred in your Vu meter there are 3 components with name missing.Please add the name so we can make it.Thanks

DELL thanks for your participation here.Nice from you.

QIAOZHI .I select this kind of receiver for you use a telescopic antenna up
to 6 foot so is light and easy to cary..There are many models but usualy they
have heavy antenna ..

HUMHUM.
I can't aswer your question .My intention is to ,,cach'' the molecular
frequency of gold and silver and Carl said is 5khz and 8,7 khz.
This property is used also in medicine to detect presence of parasites ,bugs or diseases in human body .In this way maybe we can detect not only old
buried gold or silver but also a new one.
Thanks all.

Hi,
no you misunderstud... 5Khz or 8.7Khz are not magical frequencies for gold... or anything... some CLAIMED LRL uses similar generators... 5Khz square wave cause of pseudoscientifical theories about "special" frequencies to detect particular metals etc... but these are absolutely fake informations.

So called MFID or MFD devices are claimed "multi frequency identification" or "multi frequency discrimination" but just cause they wanna emulate the famous Minelab terminology about multifrequency in PI detectors that really work.

These magnacast etc or other stuff claimed of long range MFD / MFID are fake devices for wallet mining!

It's the same when Mine-oro emulate the Mine-lab firm... using the same Mine... BUT finding Mines just in wallets of customers !

Be aware of those... or you'll waste money for nothing!

Kind regards,
Max

[Esteban]

Maybe you need a filtered VLF receiver