Circuits for Learning LRL

[Clondike Clad]

Let post circuits to help learn how a LRL works.
Let us LEARN AND TEST. it is the only way we can KNOW.
OK now all who want to teach...Soe of us is ready to build and learn.
Let start with the pick up system...

[J_Player]

Hi Clondike Clad,
The only circuit I have seen for a LRL pickup system is shown in the schematic of Morgan's pistol detector drawn by Max. This schematic looks similar to the kind of pickup circuits we find in some old 2-box detectors. In order to build a pickup circuit, you could start with the pickup circuit shown in the Morgan schematic. From what I can see the missing information for the pickup coil is not too hard because there are only 3 wires that go to the pickup coils. Maybe 2 pickup coils, or a single coil with a tap in it.

If this doesn't work, then maybe you should look for some 2-box schematic to try, or other old metal detector circuit that has a similar schematic to the schematic Max made.

Best wishes,
J_P

[Geo]

Hi J_P.
Do you mean that Alonso used a schematic from a old 2-box detector????
If yes, can you post the schematic here???
Regards

[J_Player]

Hi Geo,
No, I mean the RX part of the schematic that Max drew looks similar to some of the old 2-box circuits I've seen. I don't know of any particular 2-box circuit that is identical, but I see some similarities. Who knows what Alonso used? I see Mineoro has one of the best 2-box detectors available with extra gizmos on it. And I also see Esteban pistol detectors are made from modified old radios and metal detectors.

Maybe a 2-box metal detector would work for LRL if you made it into an omega coil arrangement.

Best wishes,
J_P

[Geo]

Thanks J_P

[Clondike Clad]

Signal from gold ,silver and diamonds

Before we can make a LRL we first must know what we are detecting.
First what would it take to pick up the signals from gold,silver and diamonds
What type of test can we do to detect the signals and what is the the signal and what part of the signal is the best to detect.
NASA Space Probes are Real LRL detectors but the keyis knowing what to detect.
So the first thing is to know or learn what to detect. Let us work on this part.

[roberts]

Question of all questions!
Bravo!

[Fred]

Before we can make a LRL we first must know what we are detecting.
First what would it take to pick up the signals from gold,silver and diamonds
What type of test can we do to detect the signals and what is the the signal and what part of the signal is the best to detect.
NASA Space Probes are Real LRL detectors but the keyis knowing what to detect.
So the first thing is to know or learn what to detect. Let us work on this part.

Exactly.How are you going?

I think the best way to discover this is to build a working device, then by looking at its reaction try to discover how it works.
Fred.

[Esteban]

Before we can make a LRL we first must know what we are detecting.
First what would it take to pick up the signals from gold,silver and diamonds
What type of test can we do to detect the signals and what is the the signal and what part of the signal is the best to detect.
NASA Space Probes are Real LRL detectors but the keyis knowing what to detect.
So the first thing is to know or learn what to detect. Let us work on this part.

With a coil, for example, the same as you can see when you detect a small coin but with very low amplitude.

[Esteban]

Based on FM and IR:

http://geotech.thunting.com/pages/metdet/patents/US5696490.pdf

[Morgan]

????

Based on FM and IR:

http://geotech.thunting.com/pages/me.../US5696490.pdf

????

[J_Player]

Based on FM and IR:

http://geotech.thunting.com/pages/me.../US5696490.pdf

Nice link, Esteban! It looks like the IR in this detector is used to relay the signal data to the headphones for the purpose of eliminating the cable, which can be a significant source of noise in a sensitive detector. But it is also intended to move the display close to the search coil to make it easier to pinpoint the target, since you won't need to look away from the coil to see the meter.

What is strange about this detector is it describes locating metal objects by transmitting a VHF FM signal several hundred feet under the ground to locate metal obects. And it has the antenna construction details shown in the patent pictures. There you go Clondike Clad. You now know the target = metal objects, the transmission distance = several hundred feet under the ground or less, the coil details are shown, the frequency is specified, --- all you gotta do is put it together and build a circuit to make it work.

Hmmm... This was patented in 1997. I wonder why we haven't seen any of these detectors in the field?

Best wishes,
J_P

[Max]

Nice link, Esteban! It looks like the IR in this detector is used to relay the signal data to the headphones for the purpose of eliminating the cable, which can be a significant source of noise in a sensitive detector. But it is also intended to move the display close to the search coil to make it easier to pinpoint the target, since you won't need to look away from the coil to see the meter.

What is strange about this detector is it describes locating metal objects by transmitting a VHF FM signal several hundred feet under the ground to locate metal obects. And it has the antenna construction details shown in the patent pictures. There you go Clondike Clad. You now know the target = metal objects, the transmission distance = several hundred feet under the ground or less, the coil details are shown, the frequency is specified, --- all you gotta do is put it together and build a circuit to make it work.

Hmmm... This was patented in 1997. I wonder why we haven't seen any of these detectors in the field?

Best wishes,
J_P

Hi,
maybe you missed the interesting spot: it in other parts of document it talks of a brighter krypton light bulb and an IR receiver that will relate to some IR emission and detect light variations....

Now I don't understand a word about that story but seems author found a different way of detecting metallic presence not just cause of VHF signal I mean.

I don't know if anybody ever built one of these things... but there's a reference to "kellyco detectors" that many here knows cause of bad fame around the TH community.

I cannot say this stuff is a scam... or doesn't work... but never saw one of these in my life... I saw many different machines but none like described in the patent.

You know also... that sometimes companies make patents for unuseful stuff... just to say "I have patents" filed etc etc etc also big companies I mean... so will not surprise me if this stuff will actually not work... but someone must build one to say!

But I cannot so I will keep my dubts!

Also... yes... there are details about coils etc... but the document is intentionally vague about real detection principle. What a surprise!

Kind regards,
Max

[J_Player]

maybe you missed the interesting spot: it in other parts of document it talks of a brighter krypton light bulb and an IR receiver that will relate to some IR emission and detect light variations....

Hi Max,
The krypton bulb is part of the data link. His patent is for using an IR LED to watch the slight differences of heat energy that fluctuate when you use a krypton bulb connected to the data signal. It has nothing to do with detecting metal, only for transmitting data without using a cable. It seems to me this is the same technique as a standard IR link, but using a krypton bulb for the transmitter instead of an IR LED. From what I can see, he believes the krypton bulb will give a better signal than an IR LED for metal detector use.

His main idea was to eliminate the cable so very weak signals were not lost because of noise from the cable moving on the shaft. He also claimed that he could keep the display close to the coil to make it easier to pinpoint too. It is hard for me to determine if he was trying to patent the VLF FM signal penetrating up to several hundred feet under the ground, but he did mention it as part of the reason to use his other claim to reduce noise with the light data link.

Since I have never seen any metal detector use his patent in the field, I think nobody has a big problem with cable noise that needs a krypton bulb to solve it. If I wanted a light link, I would use a fiber optic with IR at each end. Or even easier is an opto isolator to send a small headphone signal up the shaft on a twisted pair. I have even heard of small fm wireless mikes connected to the detector audio to broadcast a weak signal to a small FM receiver in a pair of battery operated headphones.

Best wishes,
J_P

[Clondike Clad]

passive circuit LRL

The passive type of LRL I would Like to learn.
A passive detector is picking up something?
Hung told me his detector will soon pick up diamonds.
I am still waiting for photo of his detector??????
What are the diamonds giving off????
I probe a diamond with IR pickup.emf pickup and Acostical pickup.
NOT, nota ,zero pickup.
I just don't know what to look for.
Hung can you help with this one.
My scope will only go to 100MHZ
RF genertor will go to 1GHZ
METERS UP 100 MEG INPUT INPEDENCE.
Hung I don't want to take your detector ciruit I just want to learn how to detect.