Metal detector for finding archery arrows

[Skippy]

He's trying to find many hundreds of dollars worth of arrows that are already lost., though obviously there will be ongoing losses in the future.

However, it's an interesting challenge , how to 'label' the arrow without compromising it in terms of weight, balance, aerodynamics, etc. How to get the maximum detectability for the minimum amount of added material.

I'm going to rummage in my bike spares box, I think there's some stainless steel bolts that are comparable to the arrow points. If so, I'll try and get some measurements on them.

[gravelmonkey]

Instead of trying to detect stainless steel; would a ring of self adhesive copper tape around the shaft help for detection purposes?

[Polymer]

Hello Mothough,

I would recommend the MPP E from Silverdog.
You can easily adjust many parameters with this one - for example the Pulse Width, Delay ... to experiment what works best for finding your stainless steel tips.

I work with shorter Pulse Widths and delays. Testing with nickels and small gold rings, these I can detect easily.
A stainless steel ring I have is much harder to detect well, my delay has to below 12us for that.

I can only guess at what delay times your arrow heads may need.

You probably need to experiment a bit to find out. You may actually enjoy experimenting, learning as you go.
I do, with some cursing here and there of course ...

I believe the arrow heads will be more on the surface than under the ground, so one problem less
Correct me if I am wrong here.

Cheers, polymer

[Mothough]

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.

Ehm? The offtopic stuff was not by me. Just to clarify, I do not hunt with arbalest nor kill animals. I'm a hobby archer using a recurve bow.

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

Actually, thats what I try to do.

Figured out the pulse generation. I did misinterpret the different pulses. I thought the first 4093 (IC4C) output is already the sampling pulse but it is not.
Furthermore there may be a value error in the schematic mentioned above. The delay pot P4 is only 10k, with the additional 5k1 from R25 I cannot get the delay pulse long enough. In a non-pro version of the schematic it is a 100k pot. With that combination I can easily achive 20?s of delay pulse mentioned in the Baracuda build guide.

Just to recap the different functions of the schmitt triggers in the pulse generation stage:
*) IC4C just creates the delay pulse used to offset the first sample pulse.
*) IC4A creates the first sample pulse with a width of about 40?s.
*) IC4D creates a second delay pulse to offset the second sample pulse.
*) IC4B creates the second sample pulse with a width of about 40?s.

Now lets check once again the RX preamp stage and then continue with building the sampling integrator.

Anyone know by chance how much gain the preamp stage should have? Like voltage swing of the signal. It seems I'm only getting about 2Vpp which seems quite low?

[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.

[kt315]

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

[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?

[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]

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]

[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/discussions/read.php?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

[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/discussions/read.php?2,27267,27283

Apologies for the Off-Topic post.

[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...

[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)

[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.

[kt315]

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