Metal detector for finding archery arrows

[surfdetector]

For now I'll try to build up the Surf PI design because I can do that without spending any money. Then I'll have at least a reference, since I do not own any metal detector equipment. In the following weeks I'm quite busy, so I'll probably not get to it immediatly, however I'll keep you posted. Furthermore I found a few design variations mostly differing in component values. I also found a design where the ICL7660 voltage converter seems to be synchronized and a gain potentiometer was added. Does anyone know which one is the most recent and most promissing design?

You might do well to order a PCB from here:
https://diydetector.co.uk/store/index.php

He is a forum member and his boards have a lot of mileage from the members.

[Carl-NC]

You mean that the Surf PI does not have ground balance? I thought PI detectors do not need it because they are not susceptible to mineralized ground like it is common on beaches?

Many soils have a fast enough decay that a standard PI doesn't see them. Soils that have a significant decay require a true ground-balancing PI. Probably your soil is of the former.

[Mothough]

I finally found time to build up half of the Whites SurfPI Pro design.

I'm not sure if I got the pulse generation stuff right though. Anyone wanna take a quick look?

Trace captured at different timebases:

Probes are attached like this:

[Mr.Jaick]

hello everyone
I have a question about different metals detection properties and i think it's relevant to this thread so...

which metal responds like gold when metal detecting with either a pulse induction or a VLF detector??
like in terms of depth.

this is what i'm currently thinking:
copper for pulse induction because it's detecting based on conductivity ?!
and nickel for VLF because of the similar phase shift ?!

[kt315]

1. gold and silver, platinum. low conductivity.
2. copper, ferrous, aluminium, bronze has high conductivity. we mean here Eddy current, NOT OHM CURRENT.

[Ferric Toes]

hello everyone
I have a question about different metals detection properties and i think it's relevant to this thread so...

which metal responds like gold when metal detecting with either a pulse induction or a VLF detector??
like in terms of depth.

this is what i'm currently thinking:
copper for pulse induction because it's detecting based on conductivity ?!
and nickel for VLF because of the similar phase shift ?!

Look at the chart on this website http://eddy-current.com/conductivity...y-resistivity/
The best column to compare is %IACS. (International Annealed Copper Standard). Annealed copper is regarded as the comparison standard at 100%. This chart shows that when pure metals are alloyed with other metals, the conductivity often drops dramatically.

Eric.

[Mr.Jaick]

Look at the chart on this website http://eddy-current.com/conductivity...y-resistivity/
The best column to compare is %IACS. (International Annealed Copper Standard). Annealed copper is regarded as the comparison standard at 100%. This chart shows that when pure metals are alloyed with other metals, the conductivity often drops dramatically.

Eric.

so that means whichever metal's IACS percentage is closer to gold is more likely to response to magnetic field like gold does?
like pure Aluminium 99.99% or Deoxidized Copper (Annealed)

[Mr.Jaick]

1. gold and silver, platinum. low conductivity.
2. copper, ferrous, aluminium, bronze has high conductivity. we mean here Eddy current, NOT OHM CURRENT.

i really couldn't find any chart or table that says " Metal's eddy current conductivity " or alike
tables and formations that i've found are: resistivity (Ohm/m) , magnetic permeability (henries per meter (H/m) , or equivalently in newtons per ampere squared (N/A^2))
penetration of magnetic fields for good conductors in meter...

[Skippy]

Jaick: You're hijacking a thread about finding Stainless Steel, it's not polite. Start a new thread, or search for a more relevant old thread that relates closely to your question.

However: You have failed to notice that you can't just "look for gold" , as every alloy has different electrical characteristics. 9ct , 10ct, 14ct , 18ct ,22ct, .900, are all different, and there's plenty of variation within those fineness divisions, after all 9ct is just a miserable 37.5% gold by weight, the rest can be copper, silver nickel in a variety of blends, all with different , unknown, electrical characteristics. Even high purity 22ct coins are not 100% defined, it's normally copper as the remaining metal, but sometimes a small amount of silver is used, and the resulting coins are slightly paler in colour.
For what it's worth, I tried to recreate the .900 fine alloy used in US gold coins, in order to make 'dummy coins' for test purposes, and I found that pure tin was very close, which for practical purposes meant that common 'lead-free' electrical solder alloys could be substituted ( the 99.3% Sn / 0.7% Cu alloy is a common one ). See this thread on Dankowski's forum:
http://www.dankowskidetectors.com/di...?2,27267,27283

Apologies for the Off-Topic post.

[Mr.Jaick]

Jaick: You're hijacking a thread about finding Stainless Steel, it's not polite. Start a new thread, or search for a more relevant old thread that relates closely to your question.

However: You have failed to notice that you can't just "look for gold" , as every alloy has different electrical characteristics. 9ct , 10ct, 14ct , 18ct ,22ct, .900, are all different, and there's plenty of variation within those fineness divisions, after all 9ct is just a miserable 37.5% gold by weight, the rest can be copper, silver nickel in a variety of blends, all with different , unknown, electrical characteristics. Even high purity 22ct coins are not 100% defined, it's normally copper as the remaining metal, but sometimes a small amount of silver is used, and the resulting coins are slightly paler in colour.
For what it's worth, I tried to recreate the .900 fine alloy used in US gold coins, in order to make 'dummy coins' for test purposes, and I found that pure tin was very close, which for practical purposes meant that common 'lead-free' electrical solder alloys could be substituted ( the 99.3% Sn / 0.7% Cu alloy is a common one ). See this thread on Dankowski's forum:
http://www.dankowskidetectors.com/di...?2,27267,27283

Apologies for the Off-Topic post.

my Apologies for the off-topic questions.
I thought since this thread was about finding a specific small metal(steel) so it might be relevant...guess it's not
and didn't want to add another thread for such a question cuz i thought it'd be inefficient and maybe mean!
by GOLD i mean anything between 18k and 24k, i want it for experimental purposes
btw thanks for your time on that recommendation , i'll definitely try tin as well as copper

[Mothough]

Nevermind the off-topic Jack, learned something about conductivity.

Still I want to hoist back my last post so it won't be lost:

I finally found time to build up half of the Whites SurfPI Pro design.

I'm not sure if I got the pulse generation stuff right though. Anyone wanna take a quick look?

Trace captured at different timebases: [ATTACH]53686[/ATTACH] [ATTACH]53687[/ATTACH] [ATTACH]53688[/ATTACH]

Probes are attached like this: [ATTACH]53689[/ATTACH]

[green]

Nevermind the off-topic Jack, learned something about conductivity.

Still I want to hoist back my last post so it won't be lost:

Have you found a way to detect the stainless steel heads?

[Mothough]

Have you found a way to detect the stainless steel heads?

As my previous post says I'm still at building the Surf PI Pro design.
I built it about halfway including the pulse generation. The integrator part is not yet done.
However I'm not quite sure if the coil collapse impulse and sample pulses look correct.

Did I miss a detailed building guide like they exist for other similar PI designs like Baracuda?

[kt315]

PI's are typical and you can use any building guide, bara too, for surf pi.

[kt315]

ok. give your facebook link. i must look that you are really archer. i must see on your page -
hunting with the arbalests, you with dead animals, etc. i wildy begin to doubt in your primary passages
because you did rerun on gold matter at end.