help me - help me

[sakis1]

I did this 5 months ago and have great fun>>>http://www.youtube.com/watch?v=vaOZg...gi48TujDNsFzFK ?)

[J_Player]

capacity of L1 and L2 not mentions.
best regards.

Hi kahyal.
There is no L1 or L2 in this circuit.
The only coils I drew are called the TX coil and the RX coil.
See the new corrected circuit diagram below.

I have shown all the information that you need to make both of these coils.
See the schematic and the picture of the red TX coil and the blue RX coil.
You will see in the schematic there are coil connections marked A, B, C, D, E, F, G, and H.
These are the tap connections where you connect the coil to the circuit.

Between each of these coil tap connections there are numbers which say 12T, 3T, 5T, 12T, 56T and 56T.
These are the number of turns of 3mm wire you make before connecting to the tap.

This means that for the RX coil you use 0.3mm wire and you begin winding the coil at connection F.
After you complete 56 turns, you bring the wire out from the coil 10cm distance and fold the wire to make a second tap called G.
Then you continue with more winding until you finish making 56 more turns on the same coil.
When you finsih making the second 56 turns of wire, then you take the end of the wire and mark it to be tap H.
The finished coil will be tightly packed with some tape to hold it so it will not become loose.
Then you connect the taps F, G, and H to the circuit as you see in the schematic.
See the diagram below that shows how the RX coil will look if you stretch it open to see the turns.

You can make the TX coil the same way, but you have 5 different taps from A to E.
You can look on the schematic to see how many turns are shown for each tap at the TX coil.
There is no need for knowing the capacitance or inductance of these coils.
You only need to make them as they are shown on the diagram.

Best Wishes,
J_P

[WM6]

capacity of L1 and L2 not mentions.
best regards.

Which capacity? Parasitic inter-winding capacity or inter-coil (L1 and L2) capacity?

[kahyal]

capacity of L1 and L2 not mentions.
best regards.

[kahyal]

but...........

[kahyal]

treasure or vision

............ to But these mods are outside of the scope of this project.
This will be kept strictly as a perfect unmodified factory design that people can build so they can tune signals that no other commercial locator will detect.
Then experimenters can make modifications as they choose after they begin with an authentic PD that detectors metals..............................and other your writes.

but...
thanks
best regards.

[kahyal]

treasure or vision

but..........

[Fred]

all Ok, i understand now.
Cool !!

[J_Player]

Great job JP ! ...

This is a circuit that will detect metals for sure ! (Btw, does it belongs to this forum ? )

Anyway i am sure this is a good schematic to build a working pistol detector.

At a later point one could upgrade it with an electrostatic detector connected anywhere on one of the coils and make it a perfect LRL project.

(I hope mesy something transfered the right amount to your account)

No one can claim anymore " i could not find a complete schematic on the forum" !

Hi Fred,
Yes it belongs in this forum.
We have learned that a radio receiver is an LRL, a static electricity detector is an LRL, a frequency generator is an LRL, a bent wire is an LRL, a pendulum is an LRL, and a stick is an LRL.
Everything is an LRL.
Why not a well designed antique metal locating LRL?

But we must be careful not to attach an electrostatic detector to this LRL.
This will make it unsuitable.
Remember what kahyal said when I showed him an electrostatic detector project: "...but this project is a electrostatic field detector and not a pd that detectors metals "
We know kahyal will be happy with his schematic of a fully working pd that detectors metals, and will begin building it very soon.

But others who want a combination of electrostatic and VLF will be able to receive more of the signals that are found with these unshielded loops to complete the gold signal.
Of course these experimenters will probably want to pulse their electrostatic section with a frequency generator at ELF such as the frequency of gold or silver to add the final enhancement of signal processing.
But these mods are outside of the scope of this project.
This will be kept strictly as a perfect unmodified factory design that people can build so they can tune signals that no other commercial locator will detect.
Then experimenters can make modifications as they choose after they begin with an authentic PD that detectors metals.


Best wishes,
J_P

[Fred]

Great job JP ! ...

This is a circuit that will detect metals for sure ! (Btw, does it belongs to this forum ? )

Anyway i am sure this is a good schematic to build a working pistol detector.

At a later point one could upgrade it with an electrostatic detector connected anywhere on one of the coils and make it a perfect LRL project.

(I hope mesy something transfered the right amount to your account)

No one can claim anymore " i could not find a complete schematic on the forum" !

[J_Player]

Hi J_P

I am not suggesting to increase, but to decrease value of those C (from nF to pF).

OK, I can agree with your intention to follow original design. My word "stable" was someway inadequate, I mean stable sensitivity to usefull signal, not forced stability on TX signal (locked frequency).

No problem, I support original design you posted. What about PCB?

Hi WM6,
Yes, I see your idea.
But keep in mind, this capacitor does not carry the detected metal signal.
This capacitor transfers a small amount of the power from the TX coil to the RX coil for fine-tuning of the null.
We already have the 5K pot to adjust the strength of the null compensation which passes through this capacitor.
If we make the capacitor smaller, then we will lose our ability to make full adjustment of the null to arrive at a truly null RX coil.
A smaller value here will only allow a very small part of the nulling adjustment which we need for a good null.
The actual metal signal arrives as a VLF signal that the RX coil tunes from the air at the same locked frequency as the transmitter.
The small amount of TX power that passes through this capacitor is only used for trimming to a true null without needing to move the position of the RX coil.

But your concept is good for people who want to experiment with mods farther down in the signal path after the first 1K resistor.
Once the signal is properly nulled, then we could take a smaller signal which has all the tiny spikes, and use extra amplifier stages to examine the small signals closer.
This is for people who want to make mods.
For now I agree, we should present the original factory circuit which is capable of detecting some very strange signals without mods.
I think this will be the basic circuit that all modifications are derived from.

The PCB is copyright, so I cannot publish it.
But I can see where different components are located, so we can keep the components in a similar location as the original, and devise our own circuit boards.
I am thinking that any PCB we design can be very close to the original if we keep the components in the similar location.
We should be able to arrive at equal performance to the factory-new version of this metal detecting locator.
There are some components which are intentionally kept in certain locations to avoid interference from the VLF transmissions and reception.
I think that if you were to make a circuit layout that is much different, then maybe you will lose the great detection that is found in the original factory version.

We must have respect for the designer of this circuit, because he used some very innovative methods in his design.
I look at the meter circuit, and I see a transistor used for a meter protection to prevent it from burning up in case it finds a very strong signal that is too much for the meter movement.
And I see how he used diodes to form temperature compensation at the audio amplifier.
Very few treasure hobbyists will design these things into their circuits.
Yet these are the important things when we are treasure hunting and we find temperatures fluctuating from hot sun to freezing winter times.
And what circuit protection do hobbyists use when the "Phenomenon" becomes so strong that it will damage the electronics? None...
The engineer had these all these things in mind when he designed this circuit.

I will begin work on trying to devise circuit boards similar to the same layout for the components that the original factory model has.
This will take some time.
But it will be good to wait, because we will need to see if any more errors in the schematic can be found before we have a circuit board ready.

Assuming there are no errors in the schematic, it can be used for point-to-point wiring if some hobbyists want to begin for an early start.
I know kahyal will be anxious to begin construction, now that he has the schematic that he was asking for to show a pd that detectors metals.


Best wishes,
J_P

[WM6]

Hi WM6,
You are correct. It would be more stable if we increase the value there.
But remember, we are not looking for stability.

Hi J_P

I am not suggesting to increase, but to decrease value of those C (from nF to pF).

OK, I can agree with your intention to follow original design. My word "stable" was someway inadequate, I mean stable sensitivity to usefull signal, not forced stability on TX signal (locked frequency).

No problem, I support original design you posted. What about PCB?

[J_Player]

For more stable work I can suggest this:
(or even better variable trimmer capacitor of about 0-36pF)

Hi WM6,
You are correct. It would be more stable if we increase the value there.
But remember, we are not looking for stability.
We are looking for signals that other locators cannot find.
Since there is no Faraday shield on the coils, we can expect to get extra electrical field signals even on the magnetic wave receiver loop.
We would not want to lose these electric field signals in a filter cap.
I remember when the Geotech engineer re-arranged this same exact circuit into a pistol, he was amazed at the signals he was detecting that he was never able to find with his other locators.
He tried every way he could think of to understand exactly what these signals were.
But in the end he was satisfied to know that he was detecting mysterious signals that he could not detect with his other metal locating equipment.
Since the original parts in this locator use 10nF, we must keep the same in order to preserve the original design, and not take a chance to spoil the detection of tiny signals by making modifications.

I should point out there are a few changes in this circuit from the original, because some of the original parts are no longer made.
In cases where the original part cannot be found, I substituted a part that works identical to the original, without trying to make a change the operation.

Hi J_Player
Nice drawing , circuit seem as Alonso PD !!!!.
Best regards .

Hi Aft,
Yes, these are the same rumors I heard.
But it cannot be the same because it has a meter and two control knobs.
Of course, I know nothing about the Alonso PD except people say much of it was copied from other engineers designs.

But keep in mind, this is a reverse-engineered original factory locator showing the exact components that can be seen inside on the circuit board.
Nothing has been changed except a few parts that are no longer available were substituted with equivalent parts.
I copied these parts from photos of a Geotech EE's original factory locator circuits when they were available for me to see.
So what you see here is the genuine factory model of this locator --- not a modified circuit.

The corrected version below shows more details of the parts and it adds another filter capacitor that was missing.
There may be more corrections before we have the final version.
I think I found all the errors, but I don't know the meter value.
It may be a microammeter that has 1 milliamp for full scale movement, but I don't know.
We can experiment with different meters to find the correct meter.
I am told this meter is very important for finding the tiniest of signals that you cannot hear.

See below for corrections.
Good luck building the PD and happy treasure hunting, J_P

[aft_72005]

Hi kahyal,
I can see you are a believer that a locator that detects metals will work long range when you put it in a pistol.
Maybe this is true and maybe no.
I see many people make pistols that will detect metal, but they have problems for finding long range.

I know of a circuit schematic for a detector of metals that works by transmitting VLF radio signals very far away from the pistol, then uses a receiver coil to listen for some changes in the signal that is being received.
This locator is so sensitive that it must use a nulling adjustment as well as a sensitivity control for finding signals that can originate in very distant locations.
This circuit was designed by some top electronic engineers in the USA many years ago, but it was forgotten.
What most people do not understand is this locator does not use integrated circuits which filter out the tiny signals that modern designs cannot find.
But LRL experimenters know better.
They know how important these tiny signals are for locating treasure.
They know these signals are lost when they use modern components.
This is why so many LRL experimenters look for this circuit.
I have seen many different versions of this circuit with different transistors and components ... and they do not work for most people who build it.
Maybe this is because they do not use the correct methods for building their PD.
Or... maybe it is because they do not have the correct schematic version.
I hear rumors that the pistol has a difficult time to work when the parts are changed for modern parts.

But I have the original circuit design using the original transistors and all the original components.
Some years ago I read that one of the Geotech engineers has this original locator design made into the pistol project.
He did not build a copy using modern parts.
He has the original locator from 30 years ago which he modified into a PD without changing any components.
He never will tell how much treasure he found.
I am thinking he found many ancient hammered coins, but I do not think he will tell if he found some Celtic gold treasures.
I don't know for certain because he did not say what he recovered or not recovered.
But I remember he said he received some very strange signals that he never received from any of his metal detectors.
Then he became silent.
We never again heard about any more treasures he found...
I can only guess he spends his spare time treasure hunting using his original version PD locator.
Maybe he wants to keep the original design as a secret so only he can use it.
But I will tell all details...!!

You can look below for a complete schematic.
Nothing is missing. It shows all the original parts that you will see if you open the locator and look on the circuit boards.
There are very few of these original locators left in the world.
People buy them as soon as they are listed for sale, so you will not be able to find one.
But you can build a copy from the original parts, because I show everything below.

Note: one transistor is no longer manufactured, so I put the substitute transistors that you can use to get the same results.
Also, you will need to find a mica capacitor. You can find these on ebay.
Good luck with your PD that detectors metals
J_P

Hi J_Player
Nice drawing , circuit seem as Alonso PD !!!!.
Best regards .

[WM6]

If anyone spots any errors above, please let me know so I can include them in my corrections.

Best wishes,
J_P

For more stable work I can suggest this:
(or even better variable trimmer capacitor of about 0-36pF)