Barracuda rev2

[Tibuck19]

So despite not being able to detect small stainless rivets I ll still be able to detect small silver rings and silver coins? I added a few more photo's to the drop box showing how I load and unload the battery pack. were you guys able to see the photos? I never did a link share before and not sure if it worked.

[Qiaozhi]

Stainless steel has approximately 10 times less conductivity than nickel, and 43 times less than silver.

[green]

This thread started off with a coil for a barracuda, but in light of a small issue with my board I decided to put my efforts at the Surf pi I got from Andy at silverdog, I ended with a 10" fast coil, here is the results of my efforts after many hours of cad drawing and 3d printed. Please excuse the stat of the shop! its in need of a big Big clean up! https://www.dropbox.com/sh/g8gj7aq3u...22y-3P51a?dl=0 Perhaps someone could also tell why is it I can not detect stainless steel like screws and rivets ?

I'm guessing all stainless isn't the same. A 1/4x20x3/4 stainless hex head bolt I tested had a time constant of 2.2usec about the same as 10x10mm piece cut from the side of an aluminum soda can.

[Tibuck19]

This thread started off with a coil for a barracuda, but in light of a small issue with my board I decided to put my efforts at the Surf pi I got from Andy at silverdog, I ended with a 10" fast coil, here is the results of my efforts after many hours of cad drawing and 3d printed. Please excuse the stat of the shop! its in need of a big Big clean up! https://www.dropbox.com/sh/g8gj7aq3u...22y-3P51a?dl=0 Perhaps someone could also tell why is it I can not detect stainless steel like screws and rivets ?

[Tibuck19]

I decided to remove the small buzzer that comes with silverdogs kits and plug in two 150 ohms speaker that came out of AT&T commercial phones, Wow WOw WOW now that I can hear things that I could not with what came with the kits, I am more then satisfied with depth of both boards , it nuts , where I thought I was getting six inches I was getting well over 12" granted it not as load as it is at say 8 inch but I could defiantly hear it well enough that I would dig it! now my question in light of this is How do I keep the volume high on those soft beeps or magnetic static ( not sure its the right term) and not blow out my ears when a target is closer to the coil ?? Can you guys point me to a thread on this subject or is placing a resistor or something to prevent the loudness of close targets? some sort of Arduino dsp ?

[Koala]

For the small amount of turns in this detector I doubt it would make any difference.

Copper is a better conductor and easier to solder to

Aluminium is lighter but for the same diameter has higher resistance. Difficult to solder to.


I would stick to copper .5 mm gives about the correct resistance.

[Tibuck19]

I have Yet another newbie question, What is better Copper enamel coated wire or aluminum enamel coated wire for coils ?

[kosacid]

@eclipse what about the coil meter ? i used the coil calc on the form to build mine, one at 280uH and one at 320uH, the meter say they are exactly the same rating nothing wrong with the kit stuff

[Tibuck19]

I don't recommend the DSO DIY-ers. You can get decent used analog 20Mhz scope for 50$-60$ it's much better investment, except for the space taken of course.

That is exactly what I was eyeballing, I seen a few which are very old and bulky But they are cheap and if they work and do the job, loll I just didn't want to have to invest 400$ on one just for DIY metal detectors, it would of been cheap just to buy a minelab at that point hahahaha.

[eclipse]

I don't recommend the DSO DIY-ers. You can get decent used analog 20Mhz scope for 50$-60$ it's much better investment, except for the space taken of course.

[kosacid]

go buy a dso138 they are good + note you get to build it

oh also this for coils

http://www.banggood.com/DIY-Meter-Tester-Kit-For-Capacitance-ESR-Inductance-Resistor-NPN-PNP-p-929603.html

[Tibuck19]

Just for idea sakes, what are your thoughts on a axial flux as a search coil? I was thinking of taking dividing by number of X coils to get it up to 300Uh? do you think the connections of each coil would create a bottle neck so to speak ?

[Qiaozhi]

Qiaozhi, in your option, what the minimal Hz I ll be able to use for these kind of tuning? I see the prices go up the more hz it does.

You can get away with a 10MHz scope. My digital storage scope is 25MHz.

[Tibuck19]

max the delay pot turn the trimmer till it starts to detect turn it half way test if it detects it at the right point, it should detect low at both ends and max in the middle, if it a getech barra mind bridge pin 2 and 3

My Barracuda is the version before that which Qiaozhi informed me of the EF problem with this design ver.

[Tibuck19]

ok I get what you mean, I was mistaken ground balance for Earth Field, As you mention before a oscilloscope should be a tool I would need, I just looking for the best deal possible seeing how it will on use for these purposes, I have notice that the surf Pi 1.2 does not beep as much on the swings as the barracuda, but thanks to your help I now know why. mean while I made two 10" round fast coils with out any shielding I do get a inch or two on height detection. Qiaozhi, in your option, what the minimal Hz I ll be able to use for these kind of tuning? I see the prices go up the more hz it does.