BARACUDA-Legend-1

[geoscash1]

Hey sinclairuser,

I did catch that about the 500 ohm pot, thank you for letting me know.... it was to late for an edit when I came back...

I'm gonna swap some parts around once I get that cap I have been waiting for to try some of the different ways and keep testing this board..

Mohandes, I have been testing with a few different surf pro coils (330 to 350mH) I have made for testing, they seem to work ok with the barracuda. Yesterday I wrapped a 9-1/2" (241.3mm) coil out of 18 awg (1.020mm) speaker wire I had laying around, used 28 turns for 488mH and it seems to work pretty well considering its just a loose bundle. I think once I refine it, it should be pretty good. I plan on making 10 to 12 different test coils of varying inductance for testing purposes from 280mH up to 585mH so I can better fine tune the board/coil combination with a specific coil inductance. Lots of variables to play with...

The speaker wire test coil I made yesterday ended up giving (in Air) 9" inches on a US 25¢ and 13" inches on an Australian 20 coin ($?), US 10¢ @ 8" inches, a US 1¢ penny @ 10" inches, a US 5¢ @ 7 inches, a ladies 18k gold ring at 8" inches, a beer bottle top at 12" inches and a crushed pespi can @ 30" inches. I'm happy with the results so far although I think once I find the right combo this barracuda will really kick some arse... I'd like to get the nickel and the gold ring (Silver&Gold) depths a little better so I'll keep fiddling with things to see if I can, the nickel air tests seem low compared to others I have seen or read, should be closer to 10" inches I think.


Quick test coil specs (used the coil calc):
inner radius - 4.75"/120.65mm (9-1/2" coil)
wire - 18 awg/1.020 (blue pvc coated speaker wire)
Turns - 28 = 488mH

[mohandes]

HI dear Tepco
what is your idea for this wave ?

waveform.JPG

[mohandes]

Hey sinclairuser,

I did catch that about the 500 ohm pot, thank you for letting me know.... it was to late for an edit when I came back...

I'm gonna swap some parts around once I get that cap I have been waiting for to try some of the different ways and keep testing this board..

Mohandes, I have been testing with a few different surf pro coils (330 to 350mH) I have made for testing, they seem to work ok with the barracuda. Yesterday I wrapped a 9-1/2" (241.3mm) coil out of 18 awg (1.020mm) speaker wire I had laying around, used 28 turns for 488mH and it seems to work pretty well considering its just a loose bundle. I think once I refine it, it should be pretty good. I plan on making 10 to 12 different test coils of varying inductance for testing purposes from 280mH up to 585mH so I can better fine tune the board/coil combination with a specific coil inductance. Lots of variables to play with...

The speaker wire test coil I made yesterday ended up giving (in Air) 9" inches on a US 25¢ and 13" inches on an Australian 20 coin ($?), US 10¢ @ 8" inches, a US 1¢ penny @ 10" inches, a US 5¢ @ 7 inches, a ladies 18k gold ring at 8" inches, a beer bottle top at 12" inches and a crushed pespi can @ 30" inches. I'm happy with the results so far although I think once I find the right combo this barracuda will really kick some arse... I'd like to get the nickel and the gold ring (Silver&Gold) depths a little better so I'll keep fiddling with things to see if I can, the nickel air tests seem low compared to others I have seen or read, should be closer to 10" inches I think.


Quick test coil specs (used the coil calc):
inner radius - 4.75"/120.65mm (9-1/2" coil)
wire - 18 awg/1.020 (blue pvc coated speaker wire)
Turns - 28 = 488mH

thanks for data
but my English not well and so i think better get video and put it here.
i just forgot the number of wire using for coil winding.i just now best result in 450mkH but res of coil i am forgot.
i make barracuda , please tell me about your transistors , just tell me for example Q1=mpsa13 .
regards
aha .... i get in ari testing with (250RIAL ,is Iranian coin ) in 19 to 21cm.
excuse for my English

[Tepco]

HI dear Tepco
what is your idea for this wave ?

waveform.JPG

Way too slow and strange looking, what coil type you use? Amplitude is too low, check +5\-5V supply, also scope probe and compensation. Can you adjust DC offset?

[Tepco]

Quick test coil specs (used the coil calc):
inner radius - 4.75"/120.65mm (9-1/2" coil)
wire - 18 awg/1.020 (blue pvc coated speaker wire)
Turns - 28 = 488mH

Try to find smaller possible diameter (larger gauge ) speaker wire, awg18 is unnecessarily large. Cheapest possible type, actually not good for speakers at all (high resistance) but very nice for coils, usually 2x AWG20-23 and some 2mm plastic insulation two wire cable, both wires in parallel. So, less cooper and more plastic is better for this (to avoid unnecessary metal inside coil and reduce parasitic capacitance), resistance will be still OK, target around 30 turns, or around 300uH (250-350) if you vary geometry. Your coil calc. is probably wrong, measured inductance will be somewhat lower. For really fast coil, avoid cable and connection, just leave some 1.2m speaker wire from both ends of the coil and twist every 2-3cm. After proper damping resistor selection and minimal delay adjustment you will be very pleasantly surprised with results.

[mohandes]

Way too slow and strange looking, what coil type you use? Amplitude is too low, check +5\-5V supply, also scope probe and compensation. Can you adjust DC offset?

no
this is for piking PI . i look and it is bad it is not lower than 15mks and nulling not 0v.
excuse for my English.

[mohandes]

Try to find smaller possible diameter (larger gauge ) speaker wire, awg18 is unnecessarily large. Cheapest possible type, actually not good for speakers at all (high resistance) but very nice for coils, usually 2x AWG20-23 and some 2mm plastic insulation two wire cable, both wires in parallel. So, less cooper and more plastic is better for this (to avoid unnecessary metal inside coil and reduce parasitic capacitance), resistance will be still OK, target around 30 turns, or around 300uH (250-350) if you vary geometry. Your coil calc. is probably wrong, measured inductance will be somewhat lower. For really fast coil, avoid cable and connection, just leave some 1.2m speaker wire from both ends of the coil and twist every 2-3cm. After proper damping resistor selection and minimal delay adjustment you will be very pleasantly surprised with results.

which model :
https://www.google.com/search?q=2x+A...icial&tbm=isch

about Resistance of coil , if res of coil between 1to 1.7ohm and 430mkh it is good coil ? ( for example coil should be 2.2 ohm to 4 ohm and 400 to 450mkh )
can we add 1ohm 5w in series with coil , for add res of coil ?
how can we measure capacitance of coil, and reduce that ?
excuse for my English

[Tepco]

which model :
https://www.google.com/search?q=2x+A...icial&tbm=isch

about Resistance of coil , if res of coil between 1to 1.7ohm and 430mkh it is good coil ? ( for example coil should be 2.2 ohm to 4 ohm and 400 to 450mkh )
can we add 1ohm 5w in series with coil , for add res of coil ?
how can we measure capacitance of coil, and reduce that ?
excuse for my English

This type, cheapest possible thing from nearest flea-market. For detectors like barracuda avoid too high inductance, some 300uH is good target point, resistance is not too critical, 1.5-2R is typical value, don't add anything in series. Coil capacitance can be determined by measuring SRF- self resonant frequency for known inductance, already described on this forum.

[mohandes]

This type, cheapest possible thing from nearest flea-market. For detectors like barracuda avoid too high inductance, some 300uH is good target point, resistance is not too critical, 1.5-2R is typical value, don't add anything in series. Coil capacitance can be determined by measuring SRF- self resonant frequency for known inductance, already described on this forum.

many thanks
sorry me , how can i measure SRF ? please tell me.
regards

[satdaveuk]

Also worth keeping in mind don't make the common mistake of winding to tightly because otherwise you will not only increase your inductance but also the coil capacitance, made alot of duff coils in the past due to that simple mistake.
Just firm and even pressure while winding.

[mohandes]

Also worth keeping in mind don't make the common mistake of winding to tightly because otherwise you will not only increase your inductance but also the coil capacitance, made alot of duff coils in the past due to that simple mistake.
Just firm and even pressure while winding.

so lan cable better ?
an you put here image of coil winding to teach me .
regards

[satdaveuk]

Using cat5e cable is fine but make sure its a good quality solid copper type which is around .4mm with good thickness insulation round each core , allot of cat5e cable been sold around is cc type which is crap , cc copper clad which is normally alloy coated with thin layer of copper.
I made a good coil out of .5mm LTC wh1003 cable which is stranded pure copper instrument cable.

[mohandes]

Using cat5e cable is fine but make sure its a good quality solid copper type which is around .4mm with good thickness insulation round each core , allot of cat5e cable been sold around is cc type which is crap , cc copper clad which is normally alloy coated with thin layer of copper.
I made a good coil out of .5mm LTC wh1003 cable which is stranded pure copper instrument cable.

thanks.
i buy a lot cable , cate6 , cate5 , copper wire 0.2 to 0.71mm and make a lot coil .
in all of i get better result with copper wire , for example i use the same coil for DP but copper wire get me more result about 3to5cm in air test .maybe the LAN cable have bad quality , maybe.
i search in net for .5mm LTC wh1003 cable but can not find it.
about coil shielding , what is your idea and what is your experiment ?
Excuse for my English.

[geoscash1]

Interestingly enough, I took that bundle wound test coil I was using (18 awg blue pvc speaker wire) and un-wound it and made it into a
nice tight flat wound coil, I separated the two parallel wires and used it as a single strand and wound it per specs using the coil calc, finished it up and tested it, the (my) cuda did not like it at all, even tried it on my surf pro and believe it or not it gets no detection whatsoever even after adjusting the trimmer... really odd ...


I took the other strand and re-wound it into a loose bundle coil and tried like it was before and again got good results so I'll have to assume, my particular board doesnt like a flat wound coil, only loose bundled. I checked the ohms and both were 1.6 and 1.8 respectively with inductance at 483 (or approximate 450/480mH). I ended up removing some of the winds thinking the inductance may have been to much but still, it wouldnt work down to 22 turns (approx 320mH)... It liked it as a 28 turn loose bundle really well, so I'll keep testing and winding coils till I get one I like or that seems to work the best for it.


Mohandes, sorry for the slow reply... all of my board parts are what came stock with the board from silverdog, Except, I did swap out the IRF 9640 for a tip 127 and the LF412 for TL082 but switched them back. The rest of the parts (2N2222, MPS13, MPS102, 5485, 79L05, 78L05) are all what came with it. I have a bunch of parts (6800 cap) coming from china and still waiting for them that I will be swapping for testing.

[mohandes]

Interestingly enough, I took that bundle wound test coil I was using (18 awg blue pvc speaker wire) and un-wound it and made it into a
nice tight flat wound coil, I separated the two parallel wires and used it as a single strand and wound it per specs using the coil calc, finished it up and tested it, the (my) cuda did not like it at all, even tried it on my surf pro and believe it or not it gets no detection whatsoever even after adjusting the trimmer... really odd ...


I took the other strand and re-wound it into a loose bundle coil and tried like it was before and again got good results so I'll have to assume, my particular board doesnt like a flat wound coil, only loose bundled. I checked the ohms and both were 1.6 and 1.8 respectively with inductance at 483 (or approximate 450/480mH). I ended up removing some of the winds thinking the inductance may have been to much but still, it wouldnt work down to 22 turns (approx 320mH)... It liked it as a 28 turn loose bundle really well, so I'll keep testing and winding coils till I get one I like or that seems to work the best for it.


Mohandes, sorry for the slow reply... all of my board parts are what came stock with the board from silverdog, Except, I did swap out the IRF 9640 for a tip 127 and the LF412 for TL082 but switched them back. The rest of the parts (2N2222, MPS13, MPS102, 5485, 79L05, 78L05) are all what came with it. I have a bunch of parts (6800 cap) coming from china and still waiting for them that I will be swapping for testing.

thanks
i use bf256a and bf256b , and i use bf245c and bf245b , , but i dont which transistor is better.
guide me ?