Metal detector for finding archery arrows

[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 ?!

[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:

[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.

[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.

[Mothough]

Don't know what your ground is like.

Ground is former arable land and was used for all kind of crops and since about 10 years is managed as mowed fodder meadow.

With my ground I wouldn't purchase or build a detector that couldn't GB.

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?


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?

[green]

Don't know what your ground is like. With my ground I wouldn't purchase or build a detector that couldn't GB.

[Ferric Toes]

A good and well established place is the dcg detector center in Rodenburg. Have a look at their website.
www.detectorcenter.de

Google DCG Detector Center if above does not work.

[waltr]

You might want to visit a detector dealer and take an arrowhead with you. See what will & what won't detect it. If you are lucky, they may still have a Surf PI in stock (White's just went out of business). Once you know what will work, you can then figure out what you might be able to build if you want to go that route.

Was just about to post this suggestion.
Only way to really know is to try detectors on the arrow shaft you have.

Maybe there is someone over there in the EU you can send a shaft to for testing.

[Carl-NC]

Thanks again for all the effort and details you guys are putting into this. Looks like I have to save up for one of the suggested ones.

Looking at the parts list of a Surf PI, they are all jellybean parts and I might be able to source them from my electronics bin and build one up on breadboard. Do you see any realistic chance that it would detect such an arrow head?

Are there any similar VLF like designs and would it be benificial to further up their operating frequency to make them more sensible to stainless while sacrificing detection depth?

You might want to visit a detector dealer and take an arrowhead with you. See what will & what won't detect it. If you are lucky, they may still have a Surf PI in stock (White's just went out of business). Once you know what will work, you can then figure out what you might be able to build if you want to go that route.

[Mothough]

Thanks again for all the effort and details you guys are putting into this. Looks like I have to save up for one of the suggested ones.

Looking at the parts list of a Surf PI, they are all jellybean parts and I might be able to source them from my electronics bin and build one up on breadboard. Do you see any realistic chance that it would detect such an arrow head?

Are there any similar VLF like designs and would it be benificial to further up their operating frequency to make them more sensible to stainless while sacrificing detection depth?

[ivconic]

This is similar to hunting gold nuggets, so I would suggest a VLF gold nugget detector. Something 15kHz or above. I doubt you need a high-end model (~$700) but the problem is there are not many low-priced gold detectors out there. The Fisher Gold Bug (digital) comes to mind but it is still $500. I would look for something used and older. The White's Goldmaster II or Goldmaster VSAT would be good choices. Avoid the really old White's Goldmasters in the big blue boxes, they will be useless. Another good option but hard to find is the White's GMZ, which was a stripped down GMT. Finally, an old Fisher Gold Bug would work well... this is the 1990's version that looks like the newer Gold Bug II, not the newer digital Gold Bug. Confusing, eh?

Amen to that!

[green]

Target TC and corner frequency

Question. If I made a target with aluminum foil same area and TC as head would they both detect at similar distances?

Made a target with regular strength aluminum foil. Cut a piece 12mm x 36mm and folded into a piece 12mm x 6mm(6 layers). Measured 2.6us TC same as 6mm head.

[Carl-NC]

The arrows have stainless steel heads which are 4 - 5mm (150 - 200 thou) in diameter, 3 - 5cm (1 - 2 inches) long and have a weight of 5 - 8 grams (0.2 - 0.3 ounces)

This is similar to hunting gold nuggets, so I would suggest a VLF gold nugget detector. Something 15kHz or above. I doubt you need a high-end model (~$700) but the problem is there are not many low-priced gold detectors out there. The Fisher Gold Bug (digital) comes to mind but it is still $500. I would look for something used and older. The White's Goldmaster II or Goldmaster VSAT would be good choices. Avoid the really old White's Goldmasters in the big blue boxes, they will be useless. Another good option but hard to find is the White's GMZ, which was a stripped down GMT. Finally, an old Fisher Gold Bug would work well... this is the 1990's version that looks like the newer Gold Bug II, not the newer digital Gold Bug. Confusing, eh?

[ivconic]

Target TC and corner frequency

Such TC's obviously disqualifies most of the md models we know.
Gold Bug 1 will not do it (19kHz).
Gold Bug 2 ...? (70kHz)
Gold Bug "digital"... ?

[ivconic]

I always wanted to see how will Fisher Gold Bug (2) perform on such targets?
If anybody have conditions to test it?