vlf

[Mike(Mont)]

https://www.mwlist.org/vlf.php

[Geo]

Very interesting site.

Thanks

[Mike(Mont)]

Yeah, the trick is to find a station that is operating consistently. Of course they all shut down for maintenance from time to time but there is something I haven't figured out on some of the stations that would appear to have a strong signal and yet they seem to be on the blink. I read about it somewhere they go out of phase in various areas surprisingly sometimes if they are nearby but I don't think there is any way to calculate which station will work consistently other than to try it out, and even then there are no guarantees, but that just shows that i don't know. .

[Mike(Mont)]

And I'm not even talking about atmospheric conditions.

[Mike(Mont)]

I have a SuperSID monitor. It comes with software but I like the Spectrum Labs because you can get finer detail. I guess it depends on what wave band you are working in, but for the VLF below about 45 kHz you can see what is happening in your area. Now maybe there is other software for higher frequencies, I don't know.

[daryo]

30 hz

www.mwlist.org/vlf.php

can you tell me : is the range of 30hz frequency good for treasure hunting ?(by metal detector-EM or any type of LRLs )
if used and will be good , what is it advantage from higher range of frecuency ?(20 khz)
if not ,where is used this range ? (which applications)
you know vlf means very low frequency , this is start from khz or hz ?
thank you

[Mike(Mont)]

Sorry, I am not qualified to give any advice for you. There are some projects on the forum and they can help you.

[Mike(Mont)]

I probably didn't explain this very well. If you do not know what you are doing it is best to build a project that has already been tested and shown to work. Some frequencies do not work in certain areas.

[WM6]

can you tell me : is the range of 30hz frequency good for treasure hunting ?(by metal detector-EM or any type of LRLs )
if used and will be good , what is it advantage from higher range of frecuency ?(20 khz)
if not ,where is used this range ? (which applications)
you know vlf means very low frequency , this is start from khz or hz ?
thank you

Using 30Hz as working frequency, you will face with interference problems of mains power line (60Hz in USA 50Hz in EU).

Above 20kHz skin effect phenomenon begin.

VLF range is between 3kHz and 30kHz.

Probably you need ULF (range between 300Hz and 3kHz), then try with frequencies between 600 and 800Hz and simple Wheatstone bridge solutions.

[daryo]

freq

Sorry, I am not qualified to give any advice for you. There are some projects on the forum and they can help you.

thank you

I probably didn't explain this very well. If you do not know what you are doing it is best to build a project that has already been tested and shown to work. Some frequencies do not work in certain areas.

thanks , one of my friends told me about a device that can work at range of 30hz to 20khz frequency ,but i did not know what is it means really but i think frequency not is everything while looking for ancient metals

Using 30Hz as working frequency, you will face with interference problems of mains power line (60Hz in USA 50Hz in EU).

Above 20kHz skin effect phenomenon begin.

VLF range is between 3kHz and 30kHz.

Probably you need ULF (range between 300Hz and 3kHz), then try with frequencies between 600 and 800Hz and simple Wheatstone bridge solutions.

thank you so much ,i did not know the frequency is different at countries and some of them not working at other countries , i was thinking to find a proper range of frequency for finding ancient gold ,but maybe never have success by my opinion about find freq

[Mike(Mont)]

Yeah, a 10 kHz - 30 kHz receiver is supposed to work in conjunction with the AM radio band. This is along the lines of the Gold Gun but I have no experience with that design. I think some of the designs on the forum are similar to the Gold Gun. As I recall you can get about 100 feet range (30 meters) on a large target or ore body if you have an AM radio station nearby.

[WM6]

Gold Gun is one of rare LRL design posted on this forum with real detecting potential.
Not on kilometers, but on decent detecting distance.

Probably there are a couple reasons why builders are not satisfied with GG results.
One is bad tunning procedure. Another one, even more important, is wrong detecting approach.

GG working in reflective mode should never be directed to signal source (transmitter) but always at 90° angle regarding signal source direction:

[Mike(Mont)]

I do not agree that the target creates a reflection. It is an emission at a different frequency that creates a magnetic field around the target.

[WM6]

When we talk about "magnetic field" zone, we talk about near field region of coil (or antenna), in fact reactive part of near field, where primary changeable magnetic field (magnetic induction) act. Reactive part of near field is effective region of metal detectors, and, as we know, pretty limited in effective distance.

All other field (after transition zone) is far field, where magnetic induction caused by changeable magnetic field, disappear. In far field region we can count only on resonance or on reflexion.

To get resonance with target at 30kHz (about GG working frequency) we need substantial part of Lambda (wavelength - which is here about 10km). At 30kHz we can get useful resonance (mean: re-radiated energy) with objects like underground cables, metallic pipes and alike. A hoard of coins, golden statue, etc. cannot resonate at such big wavelength.

So, using GG to detect something at say 5m, forget on magnetic field (magnetic induction) and forget on resonance. The only way is reflexive way (as per drawing above).

Without understanding how coil (which is sort of radiating antenna) works in near and far field region, proper use of devices like GG is impossible:

https://www.osha.gov/SLTC/radiofrequencyradiation/electromagnetic_fieldmemo/electromagnetic.html

[Mike(Mont)]

The magnetic field that develops around the target acts like a loudspeaker but this is not instantaneous.