pi discriminator of metals

[usefi5961]

i need discriminator schematic of metals for pi machine please if anyone have it share and how can i increase depth of this machines?
thank's.

[kt315]

depth of the pi is increasing by standart way - increasing of PULSE WIDTH. PULSE WIDTH is the EM energy we send
in a coil - more TX energy - more depth. we call it also PUMPING IMPULSE.

[Teleno]

depth of the pi is increasing by standart way - increasing of PULSE WIDTH. PULSE WIDTH is the EM energy we send
in a coil - more TX energy - more depth. we call it also PUMPING IMPULSE.

This is not true, but it's hard to explain why in a few words.

The voltage induced in a target is proportional to dI/dt, where I is the coil current. This means that a change from 0 to 1A induces the same voltage as a change from 1A to 0, but of opposite sign. Since a pulse has a rising edge and a falling edge, if the edges are too close in time (up to a few time constants), the reponses of opposite signs interact (subtraction), therefore the distance (in time) between the rise and falling edges has to be large enough.

[kt315]

sorry Teleno but we use just flyback pulse but it is related to pumping pulse directly.
DELTA PULSE has huge PULSE WIDTH (500us) that will give you 2-3m on cola can.

[usefi5961]

thank's for reply.as you explained we have limitation in pi machines .what is the maximum depth of this machines?
have a new idea for increasing response to targets?

[waltr]

Both missed a few very important ways to increase a PI depth.
1: Improvement of the Receiver circuit- no matter how strong the TX pulse is the magnetic field produced by the targets Eddy currents is very small and smaller the target the smaller the field. Two stage pre-amp is a help.
2: Pulse rate and the integrator design to optimize the signal level out of the integrator.

Depth is a function of the PI detector circuits and pulse/sample timing, the coil design as well as the target's characteristics. Therefore, not able the state depth.

However, the OP also asked about discrimination of different metals.
This can be done to a certain extent. Determining a high conductor verse a low conductor is pretty easy. My HH detector does this very well and all the info on how is in my thread (in the HH2 sub-forum).
Discriminating ferrous is much harder but I am currently working on this with ideas posted in the forums here by many people.

[usefi5961]

thank you very much for reply,sorry can you send hh2(final project) with dd coil detail again?

[usefi5961]

sorry,for more depth DETECTION and discrimination of metals what kind of detector you suggest to build?VLF or PI?

[Qiaozhi]

Your questions appear to indicate that you have a basic lack of understanding regarding metal detector technology. The majority of your posts are of the "Help me, help me" variety, and include some questions regarding LRLs and dowsing. Those subjects are handled at www.longrangelocators.com, not here in the Geotech forums where we discuss real working stuff.

Before anyone can give you a sensible answer, you need to first tell us what level of knowledge you have regarding electronics, and particularly with metal detectors. Also, it would be good to know why you're asking for this information.

[kt315]

sorry,for more depth DETECTION and discrimination of metals what kind of detector you suggest to build?VLF or PI?

build your first 2-3pcs VLFs and 2-3pcs PI's and i promise you will sure get the answer what you really need in your life.

[usefi5961]

sorry,i am electronic engineer and i know the basic of metal detectors (ib,tr,pi,vlf ) i make some metal detector such as sandbank,ib,bfo,delta pulse and i've worked with them now i want make new and advanced metal detector.

[kt315]

new and advanced you can make just in the laboratory of Minelab. we do only simlplest but effective projects.

[usefi5961]

anyway ,thank you very much for this useful site about metal detectors and challenging designers and makers.
anyway,i will take advantage of the content of this site.
good luck

[Qiaozhi]

sorry,i am electronic engineer and i know the basic of metal detectors (ib,tr,pi,vlf ) i make some metal detector such as sandbank,ib,bfo,delta pulse and i've worked with them now i want make new and advanced metal detector.

Thank you for your reply. Now we have a better understanding of your knowledge and requirements.

If you search the forum, you will find many ideas being discussed regarding techniques to improve depth, and provide better discrimination. Also, look at the various metal detector patents to get some ideas for research.

[waltr]

thank you very much for reply,sorry can you send hh2(final project) with dd coil detail again?

This is a Project in Progress with ALL DETAILS in my thread:
http://www.geotech1.com/forums/showt...ake-on-the-HH2

sorry,i am electronic engineer and i know the basic of metal detectors (ib,tr,pi,vlf ) i make some metal detector such as sandbank,ib,bfo,delta pulse and i've worked with them now i want make new and advanced metal detector.

A good starting point are the Geotech articles: http://www.geotech1.com/cgi-bin/page...e=projects.dat

As I did on my HH project is use a microprocessor for timing so easy to experiment. For example I started with the Basic PI timing that was the same as what the 555 timing chips did then from reading the forum threads here changed timing to do GEB which adds discrimination without any hardware changes.
All this is discussed in detail in my thread with links to the threads info came from.

Many other good project threads here and much discussion of other ideas including many of the patents.