Barracuda rev2

[Koala]

6"-8" sounds right to me with a 6" wide coil.

Mod for the sweep beep is very easy. One cut track and a link. As per photo I linked to earlier

Do think a photo guide to modding the original board would be a good idea for those that aren't so electronically minded

Andy made the board in good faith. The problems with the original design have only just come to light. Many original boards strangely work just fine including my own.

As soon as I finished messing with a 1265x I have acquired will mod my board and compare results.

[Tibuck19]

I wouldn't blame you or anyone if I go ahead with the Mod , and I think I will do it, simply because of the depth I was able to get before I had to tune things down far enough to solve the ground balance, I Bought my board last winter and since then Andy has be great at answering my questions (and there was a few ), and he also explained that he makes the kits to help us all out which I really appreciate and admire that, in the end you guys are the once holding these kinds open source projects a live, and keep digging deeper and enabling us all to have decent and affordable metal detectors, IF nothing else, I have learned more about induction and the balance between electrical current and magnetic fields then I would of learned by buying something like a big fancy Minelab, I am very confident I ll be able to pull it off with clear instructions, I cant really read circuit board diagrams but if there is a circle where to cut and names of components I need to add or remover I know ill be fine, Speaking of, I have a decent camera with a decent macro lens, would you guys like I take a photo at every step of the mod to help out others? I feel that you all help me so much that I feel the need to do my part too.

With that thought in mind id like to speak of something I leaned along the way, I mention I was 3d printed the coil, bobbin and housing, the one I was able to get the deepest depth on, the bobbin was printed with a filament made by Proto pasta which they call conductive pla, it is basically polylactic acid and they mix 40 % graphite in to it , make it conductive, you guys can tell me if I am right but I believe it acts like a faraday cage or shield ? I tried many with normal printing filaments and the one with this filament boosted the depth.

[Qiaozhi]

With that thought in mind id like to speak of something I leaned along the way, I mention I was 3d printed the coil, bobbin and housing, the one I was able to get the deepest depth on, the bobbin was printed with a filament made by Proto pasta which they call conductive pla, it is basically polylactic acid and they mix 40 % graphite in to it , make it conductive, you guys can tell me if I am right but I believe it acts like a faraday cage or shield ? I tried many with normal printing filaments and the one with this filament boosted the depth.

I can foresee a couple of problems with having a conductive coil shell:

1. How do you provide an effective connection from the Faraday shield to 0V?
2. The Faraday shield must not totally enclose the coil, otherwise it will act like a shorted turn on a transformer, and cause a huge decrease in sensitivity.

[Tibuck19]

I have no clue how its working , I am trying to upload a photo on here but doesn't seem to let me, ill retake them on post them on my flickr and post a link, basically I print big wire bobbins that I attach to my wood lathe so can coil it nice and tight, think of it as a U channel then I insert two half's in the U to snug it all together, I do get what you mean about shorting but maybe their is not enough graphite it in to cause that. one little thing I did find out, that you may all know already , but I didn't, it makes a difference which wire I use to plug the coil , I use the two wires from the board, if I get bad depth, or odd sounds, I flip the swap the wires and it a drastic change.

[Tibuck19]

I think I hit a depth height barrier, In light of my barracuda board version thing, I pulled my surf pi 1.2 out, it seem my little coils ranging from 250UH to 320Uh with my 155mmX250mm elliptical bobbins once adjusted for grand balance, Both the barracuda and the Surf Pi cap out at 6" on Coins. maybe my board is ok after all, seeing how I am getting same height between the two boards ?. But 6 inches doesn't sound very good. is it the coil size? Do bigger coils really get better depth, At this point im discouraged I really thought id get better, Like I said before, if I don't take into account of ground balance I can tune it to get up to 12", should I really be losing that much depth ?

[Qiaozhi]

I think I hit a depth height barrier, In light of my barracuda board version thing, I pulled my surf pi 1.2 out, it seem my little coils ranging from 250UH to 320Uh with my 155mmX250mm elliptical bobbins once adjusted for grand balance, Both the barracuda and the Surf Pi cap out at 6" on Coins. maybe my board is ok after all, seeing how I am getting same height between the two boards ?. But 6 inches doesn't sound very good. is it the coil size? Do bigger coils really get better depth, At this point im discouraged I really thought id get better, Like I said before, if I don't take into account of ground balance I can tune it to get up to 12", should I really be losing that much depth ?

Neither the Baracuda nor the Surf-PI have a ground balance feature. What are you adjusting that you think is the ground balance?

[kt315]

bara and surf are SIMPLEST pulse induction devices being good electronics base for learning by the beginners.
is that clear for you?
so WHAT you are waiting from them???
in real they are just salt underwater using ones and ground in the inveronment is not the factor you must attach importance to it.

look on the original surf and bara pics around into google. you must see - WATERPROOF housings, waterproof coils,
diving test fields reports.

1. a salt water is PERFECT electric conductor. NO Faraday field, no electrostatic field influence somewhere around the coil and housing.
absolute perfect electric conductor.

2. a salt wet sand ground is PERFECT electric conductor. NO Faraday field, no electrostatic field influence somewhere around the coil and housing. absolute perfect electric conductor.

3. where is the salt water and the wet ground in your room you doing the tests being under the water line?

[Tibuck19]

I was adjusting the delay to your reference, with uses of a small magnet a few inches over top of the coil due to my lack of having a oscilloscope, to prevent the swinging beeps of EF.

[kt315]

guys, do not write me critics in PM. please do not write. mine english is not as yours. and seems sometimes not as you wait. i write as i can!

ONLY constructive messages please.

[Tibuck19]

If you can't answer questions with respect ! then don't answer them at all! I want help from members that want to help, and understand and remembers what it was like when they first started off in the DIY metal detector thing! there is no place for smart beep beep beep remarks.

[kt315]

do not write me long message in PM. ONLY constructive offers will be welcomed. NOT BARE TEXTS!

[kosacid]

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

[Qiaozhi]

I was adjusting the delay to your reference, with uses of a small magnet a few inches over top of the coil due to my lack of having a oscilloscope, to prevent the swinging beeps of EF.

The Earth Field is eliminated automatically by the circuitry, and there is no adjustment that you need to make. The delay pot will allow you to eliminate foil, and then pulltabs as you increase the delay. Without a scope it is not possible to actually "see" what's going on, but you really need one to get the optimum value of damping resistor, and to determine the minimum possible sample delay for a particular coil.

[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.

[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.