Hi Aashif,
Before my retiring, I was for 18 years teacher in our technical university for design of digital and analog solutions. I just continue to do this.

This is the scope readings = very bad, = what you have on IC#G pins 8 and 9 ?​

Detectorist#1,
Haha, exactly! Modern tools for modern times.

However, I truly believe that while AI can translate words and explain basic concepts, it can never replace the years of hard-earned experience, intuition, and the sheer genius of a true expert like you.
...

readings with cap 0.8uf on TX​ = and where is 120 V ?...

21-st century!

Hi @Detectorist#1,

Yes, you caught me! English is not my first language, and I want to make sure I understand your brilliant technical designs perfectly and communicate my thoughts clearly to you without any language barrier. So, I am using AI as my learning and translation assistant. I...

Hi Aashif,
The contents of your comments point that you continue to wide use of AI. I hope, this will help to you to reach your aim. I have the friends that wont to use deep searching PI MD and you are the reason to my start to design such type of detector.

Hello all,

I am new to the forum, although experienced in the Superscan. How closely is this project board based upon the original Superscan?

I may be able to advise on some of the issues if closely enough related? Kind regards.

Hi all,

yep, it is possible to go below e_n = 0.3 nV/rt Hz. The AI says it.

The best option (the lowest noise) is to use two Vbe matched FZT951TA (SOT-223 housing) PNP transistors.
The FZT951TA cost only 0.53 EUR/piece. But this transistor has the lowest noise...

Hi Detectorist#1,
Thank you so much for the Rev.A schematic! The design and the built-in protection features look absolutely brilliant. I will use this PDF to carefully study the circuit and learn how the building blocks connect.

Since you mentioned that the 10-15ft depth...

.

Hello,

It might be helpful if we could take a look at your coil setup and settings. Do you have a photo of it? We might see something that's wrong with your setup.​

Hi Aashif,
I'm ready with the first variant of the schematic of "High TX Power PI Detector". The real tests on the ground will point some changes, as usually. My general idea is to design schematic solution with easy expandable TX power without changes in the design of the PCB. The different...

I couldn't get it to resonate although i put several values of capacity
i only got the resception to about 1khz - 26khz its oscilating very much whatever capacity value i put
i did follow one recommendation to put 0.82uf on both sides to get near resonance​

This is the sc...

This is the scope readings with cap 0.8uf on TX and none on Rx
...

Thank you, its almost the same as the remarks from the comments inthe forum during construction
I couldn't get it to resonate although i put several values of capacity
i only got the resception to about 1khz - 8khz its oscilating very much whatever capacity value i put
i did follow...

**YR/R Locator — Device / Transmitter**

A compact metal detector designed to locate medium-sized and large objects on the bottom, including in the coastal zone. Small and minor metal fragments are detected with reduced sensitivity.

**Detection range:**
- Roofing-iron...

It's a waste of effort. I don't know what secrets it has. The voltage is normal, 90Hz, and it can only be adjusted to half the normal pulse sensitivity at most. It's really useless.

Hi all,

how to address an amplifier input noise e_n <= 0.3 nV/rt Hz? For a gain of 50 - 200 times?
I am right now at 0.33 nV/rt Hz with ZTX851 (1x NPN).
I am sure, I can go below 0.3 nV this time. With lots of tricks.
I have seen, that the PNP type FZT 951 TA (SMD) is...

An AI generated app for generating all the results.

The app was generated using the Eq C-2 from "PI math"



Coil Inductance Calculation
The app implements the Kirchhoff-Stefan continuous multi-loop circular bundle formulation.


...

,,,...

Thanks , ill try
does it make a difference if coil windings are not tidy and organized? will it affect in resulting inductance?...

...

Hi Cristiano,

The '3M scotch 24' tape was not used in PTL search coils, but Eric may well of experimented and even used this in his own PI designs. The 'Ribbon' cable wrap method and Aquadag coating was definitely used in the Goldscan, Beachscan, etc. designs and maybe a few specials....

Thinner wire might do as well, right?

i think it was ZERO
but ill test it and post the reading
Thank you...

disconnect the coil from PCB,

put scope on Rx coil withouth C1 = case 1 and with it = case 2. What amplitude you have at 1 m ?

as i said in the first post
if i go beyond 30cm there is ZERO on Rx reception coil , nothing
i'll try synching both coils later with different capacity values
apart from that , do you have any suggestions ? Thanks...

Thank you , i already made the hinge (screws ..) to adjust the distance for balacing
i will try several values of capacity and get back to you sir
it took more that 150 turn to achieve 7 mh
i doubt i can get to 18 Mh , do have any suggestion ?
Thank you...

Thank you for your very informative feedback
although i did try several values of capacity as you mentioned , i hardly got a small improvement
iam aware of the mechanical balance afterwards , in the original post it says that optimal distance must be found first
thats why i haven't...

not perfect but it is ok, 200V is good, put Tx box 10m away from Rx box , what amplitude you havw on Rx coil , ​...

121volts...

what is the voltage amplitude on Tx coil ?...

Also, one more important thing: this is a 2box design, so the mechanical balance between the TX and RX boxes is critical.
In a 2box, the TX and RX are basically one big air-coupled coil system. The signal you get when there's no metal is called "air coupling."
You must mechanically...

Hi,
Your main issue is tuning.
The crystal doesn't set the frequency; the coil and capacitor do.
If TX and RX aren't on the same frequency, signal dies fast. That's your 30 cm problem.
Also, 7 mH coils are too small.
One working build used 18 mH (TX) and 22 mH (RX) with...

The circuit calls for 32kHz crystal

A T/R Two-Box locator operates on the principle of Induction Balance (IB).​​

​Severe Resonance Mismatch:

Currently, your TX coil and capacitor are far out of resonance, which drastically reduces the strength of the transmitted...

Tx coil value is 7 Mili henry Yellow is TX it is shown on the scope
or what do you mean by your question ?
​...

Thank you very much
in order to calibrate it you must first put them facing each other for optimal distance
only then you can put them as shown in your image and change the value of coil capacity in series and parallel to obtain resonance
My problem is very low emission ; power not...

Dear Engineer Geomax, I just couldn't manage the double-sided printing—the holes wouldn't align—so I'm going to make a single-sided PCB. I watched the video; the range is excellent, and the sound is fantastic.
Is it possible to get a list of materials? Where can I find it?...

Goggy About the coil shielding, I have seen in some Eric Foster (Ferric Toes) posted photos, that he also used a stripe like the 3M scotch 24, was this used also in production ready coils?
And regarding Vacuum Forming, do you have some photo or detauls of the machines used? (just for curiosity...

Hi kece hon,

you wrote that your coils are facing each other. Facing each other is not correct. The coil arrangement should be like seen in this example picture.

​

The original web site of the TR-Locator is here:
TRlocator
There you will find instructions...

Yes, thank you very much for answering my questions. I will go ahead and make the necessary adjustments....

what you have on Tx coil ?...

The foundational laws, and Lumped element theory.

It is good to know some calculas also. I used this book....

a little help please Mr PITO
i followed the instruction to build tr locator / 2 box
i used this latest know working schematics
instead of transistors TIP31C TIP32C i used TIP41C TIP42C which are a bit robust

i used 16 mhz quarts which gives me 3.3...

a little help please
i followed the instruction to build tr locator / 2 box
i used this latest know working schematics
instead of transistors TIP31C TIP32C i used TIP41C TIP42C which are a bit robust

i used 16 mhz quarts which gives me 3.3 khz, i...

a little help please
i followed the instruction to build tr locator / 2 box
i used this latest know working schematics
instead of transistors TIP31C TIP32C i used TIP41C TIP42C which are a bit robust

i used 16 mhz quarts which gives me 3.3 khz, i did try 32mhz the obtained...

[]...

Hi haylaz0036,

If you want to make a single-layer PCB, be aware that it will either be impractical or end up the size of a dining table. Why do you want to make a single-layer board? I used to etch and assemble almost all my PCB projects in two layers at the kitchen table. By the way, the...

Hello there; I’ve decided I want to build the single-layer PCB version. I’ve examined the board, but I’m wondering what the potentiometers on it do, and I couldn't find the parts list. Also, does the device have a discrimination feature, and if so, how is it set up? I watched the video and would...

Hi everyone
a little help please
i followed the instruction to build TR locator / 2 box
i used this latest know working schematics
instead of transistors TIP31C TIP32C i used TIP41C TIP42C which are a bit robust

i used 16 mhz quarts which gives me 3.3 khz, i did...

Hi Detectorist#1,
Wow! I am absolutely speechless. I cannot believe you actually went out and bought the parts to physically build and test the modules yourself!

This level of dedication and professionalism is just mind-blowing. Thank you so much for investing your own time,...

I also worked on the later Aquapulse 1a and 1b's and like you said they were a single circuit board. The main problems we had with the Aquapulse's were the cable connections to the Ikelite connectors. Once a little water entered, it would wick up the shielding in the orange coax cable and cause false...

Hi Altra,

With regards to the Aquapulse and Aquasport, looks like GeoMax is fully up to speed aging them. I'm afraid detectors from the 80's are a little early for my experience with the PI MD's.
I know the Aquasport is essentially the same as a Minipulse. The cylinder Aquapulse however,...

I had one coil of goldsacan 4 that had teeth so that the angle of the cheek could be moved and the other one was with the bracket from the picture made of pvc but this bracket entered the bracket that was on the coil, I opened the coil of gs 4 because as mentioned the thin layer of resin on which...

Hi Aashif,
The project of "High TX Power PI Detector" is in progress. I want to make some tests of the included modules before posting of the schematic of the first variant. Today, I buy all parts of the schematic except the materials for building of the search coil. The first variant...

While we are on the topic here is a photo of a coil I have. It came from a Goldquest. I added the 5pin connector for my TDI. It is roughly 8.5" or 21cm outer diameter. Inductance is 306uH 5.25ohm

...

Thanks, I see the 84003 on one of the Aquasport pcb the other boards that I have the labels are missing. The date codes on the ICs for AP1 are 1979, 80 etc



...

Hello Altra,

Please check the label on this circuit board. Eric usually uses the first two digits of the serial number to indicate the manufacturing year of his boards/detectors. Sometimes he adds a model series note between the year/month and the actual serialnumber. In the case of the...

Classical Single-Period / Mono-Pulse Architecture

TX Turn-On Response Analysis​

Reference: "PI Math" page 553 ​...

Thanks for the detailed information. Sorry to bother you, but you are the last link to Eric's work. Do you know about what year the Aquasport and Aquapulse 1 were in production? I used to repair these in 1990's and have the old pcb's for these models. The Aquapulse 1 had three round pcb's stacked inside...

Hi Altra,

The only coils which PTL had routinely electrostatic shielded were for the Goldscan and AquaPulse. I think Eric (PPD) also did this for his range of machines like the Beachscan, DeepStar, Aquastar, etc.. The early method for the coils used a conductive coating on the inside of...

Possible fix:

Changing your coil cable to RG-59 and replacing the shield with aluminum tape alters the electrical properties of your system so significantly that your previous damping resistor value is no longer correct. Leaving the old resistor in place is exactly why your early 10µs/15µs...

Thank you. I bought some APM Hexseals and smoth shaft pots.

Hi Goggy, Do you recall which coils had electrostatic shielding? If so how was it done?

Thanks for the information!

Hi All, not sure if you have ever taken one of the search coils apart to check the construction? The Minipulse, SuperScan, GoldScan and EuroDec all used a two pot build regardless of size right up to the 21 inch. 'Ultralight' weight resin on a 1st pot and a skim 2nd pot of high density resin (Usually...

Hi GeoMax, yes, that is correct. Pulse Technology (PTL) and PPD (Eric) shared a building. One of the perks, was that the PTL workshop made his vac-forms for him while making the ones for the Goldscan and SuperScan (up to 12 inch). Over this size were made for us by a outside fabricator.

Hi Goggy,

thanks for sharing this informations with us. From the information you provided, we can conclude that Eric also manufactured his coil housings himself, correct?

Thank you for sharing all the details !

Hi gentlemen, visited the forum after a long time away and saw your post. Thought I would reply with an FYI as I worked at Pulse Technology (and PPD) with Eric.

We used PVC rod turned / milled into swivels. PVC would solvent weld to the vac form more efficiently.

I have an...

Please substitute the LT1114 with the TL064. It also works well.
When buying the TL064, be careful if it is a Chinese-made version....

Greetings, respected teachers.

I have now reached the stage where my GS5 Lite is assembled and in use. I am not using a factory-made coil but a self-made one. The coil is 300µH with 0.7Ω resistance, and I am using RG-59 cable for the coil cable.

The problem I am facing is...

Ok, I think I found it....

Can you share the schematic for this layout? Where can I find it?...

This is the board I use for the GT—feel free to check it out.
It works for the PulseMasterPI as well.
It has a small modification that might seem insignificant, but I tested it against the standard version; with this latest one, iron discrimination actually improves a bit.​This is the...

You can use the TL084....

An easier solution is to put APM Hexseals on analog pots. It makes them waterproof.

I have built a GS5-lite that I want to use in the water (beach). As getting IP67 potentiometers is not very easy and there is always a risk of getting water inside, I was thinking about making some kind of digital actuator (digipot) in place of the actual analog potentiometers controlled by an MCU (Arduino)...

Hi Carl,

thanks for the info.

The 5-pin connector on ML coils looks like this:

​...

The LT1114 IC is very hard to find; I wonder what I can use as a substitute.

Hi @Detectorist#1,

Hope you are doing well and having a great week!

Just dropping by to say hello. I know that engineering the protection circuits and building blocks for the "BRUTAL" 24V setup takes a lot of careful thought and time, so please take all the time you...

Due to lack of time, I did not solve all the issues yet: Running the op-amp(s) out of specs, less parts, simple design.
The amplifier will be the quietest front-end ever however....

I am interested in this as well !

Thank you for your kindness. I truly appreciate your help. @amirali_sa_13 — this is my Telegram ID. I’d be happy if you send a message; I’ll be waiting for you....

Thank you, I'm eagerly waiting.​...

Has anyone if anything looked at the pcb and schematic? One fet is not marked as well as the inductance of 100uh is nowhere on the pcb and the 4 resistors are marked as R? Here are the added components, I have not reviewed the schematic in detail!...

Connect the oscilloscope ground to the virtual ground. I did the same thing.
pin1 TL062...

Yes, via the Telegram app.
I am also happy to answer any questions you might have here, to the best of my knowledge.​...

Connect the oscilloscope ground to the virtual ground. I did the same thing.
pin1 TL062...

Hi Cristiano

My original Deepstar 1 coil (11.5 inch diameter) has an inductance of approximately 320 µH and a resistance of 4.8 ohms (with cable) at 1 kHz (measured).

Hi cristiano.sar,
I think, "high power PI" means more "amper-turns" in the TX coil for equal diameter of the TX coil in comparison with usually used values for this parameter. Now days, I try to design the project of PI detector with "brutal" TX power for achievement...

Here is the pcb Eduardo two tone idx in smd checked and works!...

Eduard's two-tone scheme works perfectly normally and correctly! So that you have no need for other variants, it is important to understand the scheme and connect it correctly!

The 22k and 680pF components aren't for the PCB you built! They belong to the board with two MOSFETs in the TX section! I'll post the schematics in a few days, as soon as I have a bit more time!

Dear eduardo
please forgive me for my asks.
Can i replace bc558 or bc557 for bc639?...

Hello my friend, thank you for taking the time to send it. If it’s not a bother, I’d like to stay in touch with you more. If you have any way of contact available — such as email or Telegram — I’d appreciate it....

Where did you connect the oscilloscope probe’s GND in this measurement? When I connect the GND clip to the circuit’s virtual ground, nothing appears on the screen — but when I don’t connect the oscilloscope’s ground probe, a waveform is visible....

preamp pin 6 opamp










​



























​...

input preamp pin2 opamp





​​...