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Various metal detector circuit diagrams

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static

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i am going to start a project of metal detector.i need help for it .can i get any circuit diagram n description of this project that how it works?its really urgent
 

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Kripton2035

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www.polbox.com/p/proscan/schemat.htm

works for me with firefox (mac version)

be aware that the site I give (thunting.com) doesnt exists anymore, and that I gave a link throught an archive system webarchive that still has the datas.

if you want, I can reupload everything in the link here ?

Added after 4 hours 2 minutes:

BFO Metal Detector

by Rachel and Steve Hageman

This article describes a very basic BFO detector which uses only two transistors and an LM389 audio amplifier. The LM389, in fact, contains the two transistors that form the search and reference oscillators so the whole circuit is comprised of a single IC and a handful of discrete linear components. Accurately matched transistors are not really necessary in the oscillators so you can use discrete transistors and an LM386 audio amp instead of the LM389.

This article was published in the "Design Ideas" section of the December 18, 1997 issue of EDN, a popular electronics trade magazine that offers free subscriptions to qualifying individuals.
 

Kripton2035

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geotech metal detector

Metal Detectors

by Gavin Cheeseman

Part 1 supposedly covers a number of metal detection techniques but it focuses mainly on the BFO type. Magnetometers get some coverage, IB is barely mentioned, and PI not at all. Part 2 covers the construction of a fairly simple BFO detector.

This project was published in the May & June, 1999 issues of Electronics and Beyond, a British electronics magazine owned by Maplin Electronics PLC.END
 

Kripton2035

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eric foster metal detectors

Magnum Metal Locator

by Andy Flind

This project was published in the August & September, 1980 issues of Practical Electronics. An add-on board for modifying the mode switch function was published in 1981. The Magnum is a VLF design with ground balance and a TR discriminate mode, but lacks a motion ground balance/discriminate mode. Thus far it is the most advanced hobbyist metal detector project I've come across, amazing considering the date of publication. In 1980 the Magnum would have been a fairly advanced metal detector, just one step behind the motion discriminators that were introduced only 2 years prior.

The PDF file is a whopping 824K in size so it might take a while to download. The size is a result of two PC boards and placement images, plus numerous other graphics. In the original publication the "Front End Board" was not scaled correctly, so I have corrected this in the online version. The parts list states that a kit is available from Maplin Electronics; I have not verified the availability of this.

Practical Electronics merged with Everyday Electronics to become Everyday Practical Electronics, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd. I would like to thank Wimbourne Publishing for giving me permission to post this online version.

Comments/feedback/notes:

From Robert Mandara:

I built Andy Flind's "Magnum" detector back in 1984 and it still works just fine! Sometimes it has been slightly temperamental but I've never isolated the cause. It may just be a case of the detector responding to low batteries or not liking rechargable batteries. But when it's working it's a great machine!

You may like to note that the version of the Magnum that you have on your web site is not the same as, or as good as, the one I built. When Maplin Electronics produced instructions for making the Magnum (with Practical Electronic's permission) they also included part numbers for their ready-made circuit boards and there was a small additional board (I believe it was designed by Andy Flind) which makes the Magnum easier to use. The board makes it possible to use the pushbutton on the handle to switch between the search and discriminate modes and, in my opinion, was well worth adding. If you want, I can send you a photocopy of the Maplin version of the instructions. They're tatty but still usable. They also include some notes about possible problems constructors may face which were discovered after the PE article was published.

With the small additional board it can be difficult to know whether you are in search or discriminate mode. When the pushbutton is pressed the needle of the meter swings one way for discriminate and the other way for search - it's up to the user to learn which way it swings! If I were to make a modification to the Magnum it would be to add an LED indicator somehow to show that it was in discriminate mode. It is well worth using a good quality pushbutton on the front of the handle by the way! Poor contacts in the switch will cause the circuit to flit randomly between the modes rather than giving a decisive action.

I have not used my magnum a great deal - mainly because I like beachcombing but don't live near a beach! When I have been searching, on regularly searched beaches in the UK, I have been surprised by the depth of my finds and the apparent age of them. For example I have found many coins that had gone out of circulation, and were presumably lost, years before. Sadly I haven't found anything of great value but then I've not been looking in the right places!

I would be delighted to hear from other Magnum owners - especially if they have made good improvements to the design!
 

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mark stuart metal detector

Coinshooter IB Metal Detector

by William Lahr

This project is originally from the old Popular Electronics, August 1981. The version I have is from the 1984 Experimenter's Handbook, an annual compilation of Popular Electronics articles. This is strictly an amplitude-type detector and does not look at phase information, thus it cannot discriminate between precious metals and junk, although it does differentiate between ferrous and non-ferrous targets.
 

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2 box metal detectors project

Buccaneer IB Metal Detector

by Andy Flind

This project comes from the July, 1987 issue of Everyday Electronics. This is strictly an amplitude-type detector and does not look at phase information, thus it cannot discriminate between precious metals and junk, although it does differentiate between ferrous and non-ferrous targets. The entire kit was available (and may still be) for the cost of £54.99 (about US?) from

Magenta Electronics
135 Hunter St.
Burton-on-Trent
Staffs, England DE14 2ST
Tel 01283 565435

Everyday Electronics is now known as Everyday Practical Electronics, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd.
 

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home.global.co.za/~trh

Phaser IB Metal Detector

by "The Prof"

This project comes from the October, 1988 issue of Practical Electronics. This is a phase-type VLF detector which utilizes a very simple coil configuration. In fact, it is an example of a TR detector that is not induction balance! The author claims that it does well with the "ground effect" but he is talking about ground capacitance, not mineralization, and the design does a poor job (if any) discriminating between precious metals and junk. However, it is good reading for learning about phase detectors and might make a good starting point for designing a decent VLF discriminator.

Practical Electronics is now known as Everyday Practical Electronics, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd. I would like to thank Wimbourne Publishing for giving me permission to post this online version.
 

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metaldetectors p1 p2

Shadow Metal Detector

This VLF induction balance metal detector has a ground balance mode, 3 TR discriminate modes, and push-button tuning. It was published in the March, 1980 issue of ETI, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd.
 

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bfo pi ib detector metala

Two-box Deep Seeking Metal Detector

by Charles D. Rakes

This project is from Solid State Electronics Projects by Charles Rakes. The transmitter uses a UJT for the oscillator which can be a little hard to find (Mouser and Circuit Specialists have them). This type of oscillator is not particularly necessary and practically any good oscillator design should work.

Rakes also had a later book titled Building Metal Locators which is now out-of-print. It contains many more metal detector circuits but, surprisingly, does not include the two-box design.
 
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magenta electronics + pi

Induction Balance Metal Detector
The following report is written by Andrei Chtchedrine of Russia. It describes a pretty complex induction balance detector. His HTML page (English version) is reproduced here with his permission - you can view the original at his web site ( www.aha.ru/~aish/indexe.htm) or the Russian version at www.aha.ru/~aish/index.html. Questions are best directed at Andrei, but I will attempt to answer questions posted to Geotech as well. Thanks Andrei!
 

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/geotech.thunting.com/cgi-bin/pages/common/index.

Induction Balance Metal Detector

This is a basic amplitude-type induction balance metal detector, no ground balance, no discriminate mode, nothing fancy. It was published as "Project 549" in the February, 1977 issue of ETI, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd.
 

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ib professional metal detectors schematics

Pulse Induction Metal Detector

by J. A. Corbyn

This two-part article not only gives the construction details for a pulse induction metal detector, but also has a decent amount of theoretical explanantion on how the field of a PI coil and the target response behave. It was published in the March and April, 1980 issues of Wireless World, a popular British electronics magazine that was purchased by the publisher Reed Business Information and merged with Electronics World.

You will immediately notice that the on-screen PDF image of Part 1 is not very readable. However, once you print the PDF file the printouts are of acceptable quality. I will try to obtain a better copy when I return to the library, then rescan the whole thing and combine Parts 1 & 2 into a single PDF. I would appreciate feedback from anyone who has built this detector, especially if you have any comments on improvements. I will post any feedback on this page.
 
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make metal detector uses single ic

GoldPic Pulse Induction Metal Detector

by Trevor Hill

The GoldPic was designed by Trevor Hill and is a derivation of the Mark Stuart Microcontroller PI detector, with a bit more functionality programmed into the PIC. Trevor maintains a web site with more information at https://home.global.co.za/~trh. He has permitted me to post the schematic and documentation here.

Trevor also has available a "semi-kit" which consists of the PCB and the pre-programmed PIC chip. Please visit his web site for details. You can email Trevor at trh@global.co.za.
 

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vlf metal detector circuits

ProScan Pulse Induction Metal Detector
Schematic (PDF-131K)
PC Board (JPEG-167K)
Parts Placement (JPEG-134K)
Here it is!

This is the PI metal detector first introduced in ProScan site (www.polbox.com/p/proscan/schemat.htm). The schematic was redrawn and revised by me (Paulo Viegas) and Piotr from Proscan.

The components

Capacitors:

Non-polarized: Use good quality polyester capacitors, except for pF capacitors which can be ceramic.

Polarized: Electrolytic, voltage as indicated on plan.

Resistors

Use 1/4 watt, 1% or 5% tolerance

IC's

DO NOT USE IC SUPPORTS (sockets), those can create inductance and capacitance, and we do not want that! For 709 I recommend using the TO99 version.

VR's

Use the mini version, horizontal placement.

USE ONLY NEW COMPONENTS

Component List
Part Value
Capacitors
C1 100uF/16
C2,C13 47nF/63
C3,C11 100nF
C4 1nF/63
C5,C24,C15,C16,C17,C19 47uF/16
C6 47nF
C7,C10,C12 150nF
C8 10pF
C9 3.3pF
C14 15nF
C18 68uF/25
C21,C22,C23 1nF
Diodes
D1,D2,D3,D4,D6,D7 1N4148
Variable Resistor (mini VR)
P1,P2 100K
P3 10K
Resistors (1/4W, 1% or 5% Tol.)
R1 43K
R2,R7,R13 1.1K
R3,R10 1K
R4 330
R5,R12 220
R6 100
R8 300
R9 820
R11 520K
R14,R16 10K
R15 110
R17,R21 2.3K
R18 750K
R19 220
R20 6.8K
R22 1M
R23,R26 11K
R24 130K
R25 30K
R32,R35 18K
R33,R36 8.2K
R34 91K
R709 100K
Transistors
T1 BC560C
T2 BD911
T3 BF245
T4 BC560C
IC's
U1,U5,U6 555
U2 79L05
U3 709 (MAA501 as in plan, is a Czech equivalent to 709)
U4 741
U7 78L10C
U8 4093
Other
L1 Search Coil, 20cm diameter of 25 windings of insulated copper wire (~22AWG)
S1 Female Jack Phones for PCB (optional)
PCB

The PCB for this project is a JPG file (PCB1), the final printed dimensions should be ~65mm X ~130mm. I recommend using the photo process to create the tracks, since the circuit is more or less complicated. After printing PCB1 flip the paper, the printed surface is the one that will be in contact with the copper layer. The components placement is in file PCB2.

Please note that there's four jumps, make then with standard isolated copper wire. The S1 (jack support) is optional, and can be placed in the case. Keep the components with short leads, and close to the pcb, to avoid capacitance and inductance.

Note: I've taken much care in making this pcb, I believe no tracks were forgotten (since this is insured by the software), nevertheless if any error as to be found, please inform me right away. [paulo_viegas@hotmail.com]

IMPORTANT

After making the pcb, please check the tracks that go inside 4093 pins, insure that they are not short-circuited (correct with a x-acto blade if needed).

Circuit Description

"Basically U1 is a timer integrated circuit that is wired as a pulse generator. The output on pin 3 is a negative going pulse of a width that determines the width of the transmitter pulse. This is repeated at a certain frequency that is the transmitter pulse rate. This pulse train drives T1, which inverts it so that it is then a positive pulse driving the base of T2. T2 is the transmitter output stage driving the search coil, L1, in its collector. U2 is a voltage regulator that takes the negative battery voltage and gives -5V output for the receiver amplifiers U3 and U4. R7 across the coil is a damping resistor to stop the coil ringing. The live side of the coil then goes through a 300? ohm resistor to pin 2 of U3 which is a wide band receiver amplifier. The two back to back diodes prevent the transmitter switching transients from damaging U3. After amplification the signal goes to the sampling gate T3. This acts as a switch that is closed until a short time after the transmitter pulse has ended (pulse delay) This delay is generated by the 4093 dual monostable which is triggered via C4 from the transmitter waveform. The first half on the 4093 generates the delay duration while the second half generates the time that the gate stays open. U4 is a single ended integrator which takes a running average of the samples of the amplified receiver waveform. When there is no metal near the coil the sample will be approximately zero; bring metal near to the coil and the sampled decaying waveform from the metal will cause the output of U4 to rise. This dc output goes via R17 to the transistor T4 which controls another timer IC, U5, to generate the audio pulses. The audio output is a tick that increases in frequency as metal is brought closer to the coil. The threshold tick is set by P3 that alters the bias on the other input of U4. Headphones can be connected to pins 3 and 2 of the connector on the right of the schematic. A resistor in series here might be necessary to adjust the volume. At the top left of the schematic U6, is another timer that generates a separate pulse train that is then rectified by the diodes D1-D4 to give a positive dc voltage which is then supplied to the positive 10V regulator U7 which gives the positive supply necessary for the receiver IC's. P1 is a preset resistor that sets the dc output level on pin 6 of U3 to 0 volts. It is useful to connect an oscilloscope to this point for testing to see that everything is working OK. The only thing that I can't show here are the various waveforms and their relationship with each other. These are controlled by the components around the timers and the monostables and are fixed by the values given in the schematic. So if everything is assembled right the only setup adjustment is P1." Eric Foster

Eric's suggestion:

"I would suggest making R8 1K0, R11 1M0 and deleting R9. This will give a gain of 1000 for the first stage and the 709 will be stable with the compensation values given. What sometimes fails rather than the diode is the input resistor R8 and possibly the damping resistor. Both of these resistors experience the peak voltage across them and can go open circuit unless a high quality metal film resistor of adequate rating is used."

Acknowledgements

I would like to thank:
Piotr for giving the first schematic and revising the new one.
Eric Foster for giving the explanation on the circuit, and commenting it
All the guys (Phil, Vlad, ...) that commented this on Eric Foster's Forum (www.insidetheweb.com/messageboard/mbs.cgi/mb122618)

My wife, for being sooooo patient when "I'm on the computer".

Regards to all,
Paulo Viegas, Portugal
paulo_viegas@hotmail.com
P.S. - Sorry for any English error!!

Notice

Here is a note from Paulo regarding possible errors in the Proscan:

I've received mail regarding errors in Proscan PCB an possible error in schematic. I've corrected the error for T2 BD911 in the PCB (my pcb program had this component in incorrect pin-out).

Now, regarding T4 BC560 i had a post saying that it was incorrect wired in scheamatic, i'm waiting for confirmation on this, if so i'll correct it also. -Paulo

I will post the corrections as soon as I hear back from Paulo. -Carl (06/21/99)
 

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Kripton2035

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pic vlf metal detector circuit

EE Treasure Hunter

by Mark Stuart

Here is a pulse induction metal detector that is fairly basic, and is the predecessor to Mark Stuart's Microcontroller PI detector project. You can also find some strong similarities with the GoldPic project. It was published in the August, 1989 issue of Everyday Electronics, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd.

Note: The original schematic had the bipolar transistors drawn incorrectly. This has been corrected.
 

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pol box proscan schemat

Microcontroller PI Treasure Hunter

by Mark Stuart

Here is a pulse induction metal detector that uses a PIC16C54 microcontroller to control the pulse timing and the sample and hold. It was published in the June, 1994 issue of Everyday with Practical Electronics, a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd.

The entire kit is available for the cost of £63.95 (what's that, about $ 100 US?) from

Magenta Electronics
135 Hunter St.
Burton-on-Trent
Staffs, England DE14 2ST
Tel 01283 565435

When this article was published the only source for the programmed microcontroller was Magenta or the author and it was pre-programmed and not modifiable by the user. Due to the generosity of Mark Pauls, we have available his PIC code so not only can you program you own PIC, you can make timing modifications as you like.
 

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