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. :shrug:

Best wishes,
J_P

[Geo]

Thanks J_P:)

[Clondike Clad]

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? :D

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/metdet/patents/US5696490.pdf
????:eek:

[J_Player]

Based on FM and IR:

http://geotech.thunting.com/pages/me.../US5696490.pdf (http://geotech.thunting.com/pages/metdet/patents/US5696490.pdf) :eek:
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. :thumb:

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

Best wishes,
J_P

[Max]

:eek:
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. :thumb:

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

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! :rolleyes:

But I cannot so I will keep my dubts! :lol:

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]

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.

[J_Player]

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.Hi Clondike Clad,

I have heard rumors that long range diamond detectors don't pick up the signal from a diamond directly. Long range diamond detectors are associated with picking up a signal from airborne carbon-containing gasses that are given off from deposits left by various ungulates in the vicinity where buried diamonds are located. I am not sure how to build a passive electronic detector that can do this.

Best wishes,
J_P

[Max]

Hi Clondike Clad,

I have heard rumors that long range diamond detectors don't pick up the signal from a diamond directly. Long range diamond detectors are associated with picking up a signal from airborne carbon-containing gasses that are given off from deposits left by various ungulates in the vicinity where buried diamonds are located. I am not sure how to build a passive electronic detector that can do this.

Best wishes,
J_P

Hi,
do you mean the detector sniff ungulates' BS ! :lol:

Kinda of sniffer thing! ;)

Kind regards,
Max

[Fred]

:lol::lol:

A detector that detect expensive perfumes molecules could lead you to diamonds too.
I´ve been told it work with paper money and gold too.

regards,
Fred.

[Esteban]

IR light ionizes the air, so in this smal beam is created more "hot" and ionized air. Light acts as an antenna. Imagine this active antenna. IR is very good for electronic LRL, and don't know why more people don' work in this field. The IR light must be modulated. For more precission, no a fixi light in wich you introduce the modulation. You must be modulated open a clossed the beam at the desirable frequency, best two IR leds. This is a King.

[Max]

IR light ionizes the air, so in this smal beam is created more "hot" and ionized air. Light acts as an antenna. Imagine this active antenna. IR is very good for electronic LRL, and don't know why more people don' work in this field. The IR light must be modulated. For more precission, no a fixi light in wich you introduce the modulation. You must be modulated open a clossed the beam at the desirable frequency, best two IR leds. This is a King.

Hi,
but IR are not ionizing radiations as I know... you can ionize stuff using e.g. short UV, x-rays, gamma-rays and other stuff but not IR.

Look here: http://www.osha.gov/SLTC/radiation_nonionizing/index.html

Kind regards,
Max

[Esteban]

Hi,
but IR are not ionizing radiations as I know... you can ionize stuff using e.g. short UV, x-rays, gamma-rays and other stuff but not IR.

Look here: http://www.osha.gov/SLTC/radiation_nonionizing/index.html

Kind regards,
Max

Hi Max

Wish to say "excites molecules", and IR have not temperature apparently, but yes energy.

Regards

Esteban

[Esteban]

Remote sensing by micro-radar: Put free, wait 30 seconds (has a counter) and put the code and download:

http://rapidshare.com/files/94017559/MIR_Overview.pdf.html

[J_Player]

Thanks Esteban,
Great article :thumb:

Best wishes,
J_P

[Fred]

Remote sensing by micro-radar
Hi Esteban,
Really cool device.Thanks!,
Fred.

[Esteban]

OK.

Have an idea. What happens if we usel quartz rod for to sense electric fields? Also can improve very much the LRL rods :D

[J_Player]

maybe you will have a hard time hearing because of sound from the quartz. :rolleyes:

[J_Player]

Have an idea. What happens if we usel quartz rod for to sense electric fields? Also can improve very much the LRL rods :Dmaybe you will have a hard time hearing because of sound from the quartz. :rolleyes:

[Fred]

maybe you will have a hard time hearing because of sound from the quartz. :rolleyes:

Whaaat ? say again ? :)

Esteban, do you know this page? very well documented.
regards,
Fred.
http://www.techlib.com/science/ion.html

[Esteban]

Whaaat ? say again ? :)

Esteban, do you know this page? very well documented.
regards,
Fred.
http://www.techlib.com/science/ion.html

Hi Fred,

Thanks a lot!

Regards

Esteban

[Esteban]

maybe you will have a hard time hearing because of sound from the quartz. :rolleyes:

No, this not disturbing sensor can be an extraordinary tool for electronic LRL. Here is used a quartz rod 30 cm long 4 mmm diam. See the patent:

http://www.google.com/patents?id=3gMEAAAAEBAJ&dq=6,107,791

Regards

Esteban

[J_Player]

No, this not disturbing sensor can be an extraordinary tool for electronic LRL. Here is used a quartz rod 30 cm long 4 mmm diam. See the patent: http://www.google.com/patents?id=3gM...J&dq=6,107,791 (http://www.google.com/patents?id=3gMEAAAAEBAJ&dq=6,107,791)Hi Esteban,
The patent shows that this quartz apparatus is designed to measure the near static charge of the air without disturbing it by using metal sensor wires. Does this mean you think we can locate long range metal targets by measuring only the near static charge of the air with a quartz sensor? Or is more circuitry needed to locate a long range target?

Best wishes,
J_P

[Esteban]

Can be useful for measure electric activity in site with long time buried metals. Maybe for 5 or 10 meters.

[Fred]

No, this not disturbing sensor can be an extraordinary tool for electronic LRL. Here is used a quartz rod 30 cm long 4 mmm diam. Regards Esteban
Hi Esteban,
This look interesting for electric field,not disturbing field.But what about magnetic field ?
It is important too.
Regards,
Fred.

[J_Player]

This look interesting for electric field,not disturbing field.But what about magnetic field ?
It is important too.Maybe the quartz rod does not disturb the magnetic field too much same as not disturbing the electric field too much?

Best wishes,
J_P

[Fred]

Maybe the quartz rod does not disturb the magnetic field too much same as not disturbing the electric field too much?

Best wishes,
J_P
Hi
What i mean is : what Esteban intend to use if he wants to detect also the magnetic field?
Regards,
Fred.

[Esteban]

Hi
What i mean is : what Esteban intend to use if he wants to detect also the magnetic field?
Regards,
Fred.

You can detect via

PASSIVE

1. magnetic system (absorptive)

2. electric system (type microvoltmeter)

3. combination of both (absorptive + microvoltmeter)

4. radiofrequency (simple radio receiver) (maybe sense combination of both - electric and magnetic fields)

5. Others...

ACTIVE

1. I/B + RF sniffer (active + passive)

2. Off-resonance + RF sniffer (active + passive)

3. Other kind of MD + RF sniffer (active + passive)

4. IR beam + RF sniffer (active + passive)

5. Ultrasonic beam + RF sniffer (active + passive)

6. IR laser beam + RF sniffer (active + passive)

7. Other type based on emission + RF sniffer...

8. Etc.

Here, RF sniffer can be simple FM radio.

This combination + sensors you can use extend the possibilities.

[Fred]

Ok thanks Esteban,

I see the common base is RF sniffer, enhanced by some other device.But to pick up RF you need RF to be generated somehow, what gives best results?
Sorry for so many questions.:rolleyes:
regards,
Fred.

[gold24h]

A bfo metal detector circuit with an exturnal coil generates an rf,long time buried metal at a distance will disturbe the rf in the coil,you can hear this little disturbance with an fm raido where the antenna is near the coil.I am building a unit but i do not know how to set the radio,do you set to a empty channel or one brodcasting?

[Fred]

A bfo metal detector circuit with an exturnal coil generates an rf,long time buried metal at a distance will disturbe the rf in the coil,you can hear this little disturbance with an fm raido where the antenna is near the coil.I am building a unit but i do not know how to set the radio,do you set to a empty channel or one brodcasting?
Hi,

I have no idea.If you are generating a freqency, i suppose you should try to tune to this frequency?
This looks interesting , it should be easy for you to try both .Did you really notice this effect?
Regards,
Fred.

[Esteban]

A bfo metal detector circuit with an exturnal coil generates an rf,long time buried metal at a distance will disturbe the rf in the coil,you can hear this little disturbance with an fm raido where the antenna is near the coil.I am building a unit but i do not know how to set the radio,do you set to a empty channel or one brodcasting?

Yes, is in the list and others many posts by me:

ACTIVE

1. I/B + RF sniffer (active + passive)

2. Off-resonance + RF sniffer (active + passive)

3. Other kind of MD + RF sniffer (active + passive)

4. IR beam + RF sniffer (active + passive)

5. Ultrasonic beam + RF sniffer (active + passive)

6. IR laser beam + RF sniffer (active + passive)

7. Other type based on emission + RF sniffer...

8. Etc.

Here, RF sniffer can be simple FM radio.

[gold24h]

Hi Fred,i have not experimented with this before,but if you read the posts from ESTABAN in the last several months he givs hints on how the pistol detectors from the past worked,he knows what he is talking about.I am building a bfo metal detecter based on a microchip circuit with an external coil of 70 turns of wire,the only problem is it occilates at 88 kilohertz,this may be two low,i will run a sheiled cable from the antenna conection of a hand helded fm raido to a loop antenna near the coil of the bfo.

[J_Player]

the only problem is it occilates at 88 kilohertz,this may be two lowEsteban has said the workable frequencies are between 45 KHz and 160 KHz.

Best wishes,
J_P

[Max]

You can detect via

PASSIVE

1. magnetic system (absorptive)

2. electric system (type microvoltmeter)

3. combination of both (absorptive + microvoltmeter)

4. radiofrequency (simple radio receiver) (maybe sense combination of both - electric and magnetic fields)

5. Others...

ACTIVE

1. I/B + RF sniffer (active + passive)

2. Off-resonance + RF sniffer (active + passive)

3. Other kind of MD + RF sniffer (active + passive)

4. IR beam + RF sniffer (active + passive)

5. Ultrasonic beam + RF sniffer (active + passive)

6. IR laser beam + RF sniffer (active + passive)

7. Other type based on emission + RF sniffer...

8. Etc.

Here, RF sniffer can be simple FM radio.

This combination + sensors you can use extend the possibilities.

Hi,
about this "RF sniffer" or FM radio what do you mean ?

Someone already asked this...

I mean... what you do with FM radio ? tune to a broadcast station ? Tune to free slot (just background noise) ? Or just modify the radio for change e.g. frequency ...bands etc ?

I don't understand what's the purpose of this RF sniffer.

Kind regards,
Max

[Max]

Esteban has said the workable frequencies are between 45 KHz and 160 KHz.

Best wishes,
J_P

Hi,
yes right... but he wrote also that this "RF sniffer" works in FM : and I read this both frequency modulation and FM-band ...if he doesn't modify the radio he will tune e.g. from 88-108MHz and so ?

What's relationship between a 50KHz signal not modulated in frequency (do you know any detector that made this modulation of signal ???) and a frequency modulation receiver that maybe runs at 88Mhz (if he doesn't modify radio) ???

This thing seems have no sense. But maybe he will explain us what kind of relationship will be between the two things! :rolleyes:

Kind regards,
Max

[Esteban]

Hi,
about this "RF sniffer" or FM radio what do you mean ?

Someone already asked this...

I mean... what you do with FM radio ? tune to a broadcast station ? Tune to free slot (just background noise) ? Or just modify the radio for change e.g. frequency ...bands etc ?

I don't understand what's the purpose of this RF sniffer.

Kind regards,
Max

In the past I put in extreme free of band.

Is better modify the radio quite one turn of the 3 turns used in FM, so this extend to 108 to 130 or more Mhz, out of poluited FM here we have.

Also I want to know how is the purpose of the antenna (no telescopic, I use only a cable around search head), but is useful for to detect this old items, and don't know why, maybe rediadated signals from different radio sources...

Also the audio is useful for to ampplify the BFO detection...

This is an empiric theme, because as you don't have scientific papers in this field, your way is the experiment and see wich is better results. :)

[Esteban]

Hi,
yes right... but he wrote also that this "RF sniffer" works in FM : and I read this both frequency modulation and FM-band ...if he doesn't modify the radio he will tune e.g. from 88-108MHz and so ?

What's relationship between a 50KHz signal not modulated in frequency (do you know any detector that made this modulation of signal ???) and a frequency modulation receiver that maybe runs at 88Mhz (if he doesn't modify radio) ???

This thing seems have no sense. But maybe he will explain us what kind of relationship will be between the two things! :rolleyes:

Kind regards,
Max

Maybe no relation between these both frequencies, but put a loop around a radio an generate a tone... you'll hear clearly in audio section... See here a loop that creates the tone.

Isn't in books! :lol:

[Esteban]

Esteban has said the workable frequencies are between 45 KHz and 160 KHz.

Best wishes,
J_P

Yes, more low frequencies mean minus hertz variation. "Excess" of Khz (300) you have here detected very well paper plated of box cigarettes...

[Max]

Maybe no relation between these both frequencies, but put a loop around a radio an generate a tone... you'll hear clearly in audio section... See here a loop that creates the tone.

Isn't in books! :lol:

Hi,
some FM radios (almost all old stuff as far as I know) can detect small amplitude modulation (narrow) when they are in frequency demodulation mode. This happens cause of some transistor there that works as rectifier and then some detection happens by amplitude too not just frequency modulation.

My guess is that, if you put the coil with tone signal (amplitude modulation) near radio in FM mode... it will pick up that tone by amplitude demodulation that happens there.

Very easy to test... nedd just one e.g. remote control and an FM radio... put it into FM and near the remote on the back side... the inductive coupling between radio coils and remote tracks with currents flowing in... will give you hear the sound of on-off modulation at IR led(s)... so to sense the currents and relative EM fields.

But if you switch in AM mode you will hear much more loud... cause it's dedicated demodulator there... with e.g. germanium diodes (old stuff radio like you posted).

My question is: why use FM if you look for amplitude modulation ?

When you talk about BFO you mean there's some frequency mixing somewhere and this will be detected by FM radio as frequency (variant) modulation ... and thus amplitude modulation residual information is just a part of what you are looking for? ;)

Kind regards,
Max

[Esteban]

Hi,
some FM radios (almost all old stuff as far as I know) can detect small amplitude modulation (narrow) when they are in frequency demodulation mode. This happens cause of some transistor there that works as rectifier and then some detection happens by amplitude too not just frequency modulation.

My guess is that, if you put the coil with tone signal (amplitude modulation) near radio in FM mode... it will pick up that tone by amplitude demodulation that happens there.

Very easy to test... nedd just one e.g. remote control and an FM radio... put it into FM and near the remote on the back side... the inductive coupling between radio coils and remote tracks with currents flowing in... will give you hear the sound of on-off modulation at IR led(s)... so to sense the currents and relative EM fields.

But if you switch in AM mode you will hear much more loud... cause it's dedicated demodulator there... with e.g. germanium diodes (old stuff radio like you posted).

My question is: why use FM if you look for amplitude modulation ?

When you talk about BFO you mean there's some frequency mixing somewhere and this will be detected by FM radio as frequency (variant) modulation ... and thus amplitude modulation residual information is just a part of what you are looking for? ;)

Kind regards,
Max

Yes, of course, this is the reason for to use the IR beam instead the BFO MD. You generate the tone and you can adjust the system for to leave stable and sensitive.

I use FM mode because is very more clean than AM. If you don't use the IR or loop for to generate the tone, or BFO MD, or I-B MD in conjunction FM radio, only the FM radio, well also works only the FM and don't know why! Also any RF clean receiver... For example, I bought a wireless bell and I use the receiver part (only for check if this can be useful), well also works. :lol: