DISCRIMINATION NEEDED ON PI

[daverave]

i went out onto the beach several days ago and was very frustrated by the amount of signals i got mainly from trash items using my home made pulse machine,i feel now maybe pulse machines are better for fairly clean beaches for special applications...surely there must be some way of rejecting large junk items and some iron, i have an electronic engineering background and the only way i can see any trash rejection is maybe sampling on the tx pulse or multi samples in different positions on the back emf waveform...can any one please share their thoughts on this.

 

[Mega]

That is the biggest problem with a PI machine and although Garrett suggest its possible with the SeaHunter,ATX and Finny the GPX is slightly better but of course at a massive price and only with a DD coil.I own and use one of the original Crossbows from Geotek fame and although it does not have any form of discrimination its possible i feel to hear a slight tonal differance with iron although its still hit and miss.

Although in theory a PI is the best machine for the beach they are not alway the best one in practice,not really sure what to suggest,i mainly use my PI for hoard detecting but that in only after i have cleared the site as best i can with a VLF machine and a big coil,then you stand a better chance of without finding much iron.

If it was easy and a Pulse could be improved much better than what they are at the moment alot more folks would be using them,but unless you have a deep pocket for a GPX then not alot else can be done.

 

[daverave]

i really prefer pulse detectors but without any discrimination its really time consuming where there is lots of junk...at present im using more my old trusty tesoro stingray which is good disc but poor depth,i know a detectorist who uses a troy shadow x5 which has good depth but with slight salt beach chatter which i guess is not a big problem cause even pulse machines can false signal on wet sand...i think machines like garrett atx....minelab gpx/gpz are way overpriced for what they are and very heavy and also the ml sovereign range have a very slow recove ry speed which will miss good targets near to junk...so nothing i guess is perfect...the only sort of discrimination i get with the pulse is a double bleep on things like nails in a horizontal pos
ition which sometimes can be of some help.

 

[Sven]

Dave put together the Mirage Primo 2, think I sent you one of those boards.
Then go out and see what you think

 

[daverave]

Hi Sven

i will do the primo project first and see how i get on with it....my problem is soda cans and beer bottle tops which cause much frustration on my local beach...iron is not a big problem so much....my coil also is not good at pinpointing which makes things worst although the other coil i made being dual field is far better at pinpointing......if the primo
will give me some sort of disc it would be a great help.

 

[metalpopper]

i went out onto the beach several days ago and was very frustrated by the amount of signals i got mainly from trash items using my home made pulse machine,i feel now maybe pulse machines are better for fairly clean beaches for special applications...surely there must be some way of rejecting large junk items and some iron, i have an electronic engineering background and the only way i can see any trash rejection is maybe sampling on the tx pulse or multi samples in different positions on the back emf waveform...can any one please share their thoughts on this.

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Hello Dave, and welcome.

It's good to meet a fellow detectorist who also has an electronics background to complement his interest/enjoyment of metal detecting.

You are at the beginning of a long, demanding journey when you start applying your present experience (can you enlarge on that?) to investigate relevant sciences

of the physics involved in the field of magnetics and associated materials

About 50 years ago, as a young electronics engineer, I was asked if I could possibly repair an American 'Mineral detector', belonging to the son of our department's secretary.

I was then employed as head of a Nuclear medicine electronics lab.;.... but not aware of the hobby's existence in the UK.

I accepted the challenge, for I had all the best technology of the day, at my disposal,

Eventually, by use of an X-ray machine, I finally pined the problem down to the search-coil.

Using medical scalpels, I did a 'lobotomy' on the search-head, and repaired the fault..(disconnected wire to Faraday shield coating).

Using a chemical concoction from the mechanical workshop, the disseminated plastics were soundly restored.

A week later, I was shown a target found with it, from a local 200 year old park....A fabulous ruby and diamond gold ring dating from the 1840's !

In appreciation, the young boy sent me a 1/4 pound bag of 'dolly-mixtures', bought from Woolworth's !

Needless to say, I was impressed by the find....and hooked by the concept of metal detecting.......I just had to know the concepts involved.

That began an intriguing journey of technical and theoretical research, that continues to the present day.

So from the primitives of design in the 1960/70's, to today's sophisticated detectors.....I've followed the trail with insatiable curiousity......Matt