silverdog pi coil

[sinclairuser]

i have been asked by andy(silverdog) to post a few lines about a coil he asked me to test, these coils have been made by andy for his pi projects so users can get a decent coil without having to wind one.
the one i have is made in one of dons 9" shells, once i retuned the barracuda to stock specs it worked fantastic (330 damping resistor).
i got 14" yes inches in air on my gold sample, 3/4 of a metre on a 1lb cannon ball(iron) at 25us, perfect for your barracuda kits, i got 10" in the sand pit for the gold but it is a large chunk.
at 12us (as low as my barra goes), in air, no real difference though it seemed a bit skittish, in the sand the depth was not any different but the response to the gold was more distinct, at 25us it sort of fades in, at 12us it booms in like a fisher(if you know what i mean), though the skittishness(slight instability) was there.
but that is due to this coil being unshielded, andy is working on these and shielded ones currently, though i dont think the shield is needed on the standard setups, so much so that i am leaving the 330 resistor in this barracuda, and intend to run this coil of andy's.
so if and when he starts selling them, i can fully recommend them, they are the kind of quality you expect from silverdog, i'm away in devon this next week and intend to properly test it, i will post an update when i return.




thanks ally (sinclairuser)

[dfbowers]

Glad to hear that Andy is making them. Sounds like you are getting decent results. I might recommend using micro-balloons as a filler to stretch and lighten the epoxy a bit.
Also, how is the fit for the coil covers?
Don

[Koala]

That's very impressive results well done

[fotoguy]

sinclairuser; Do you have information as to AWG size, stranded wire, magnet wire, and turn count? Those are great results! Thanks for the share. I don't want trade secrets, I'm sure a lot of folks are curious.
Best
fotoguy

[sinclairuser]

@ don they fit perfect mate, dont change a thing.
@fotoguy i dont know, i got it off andy put a coil plug on it, put a 330 ohm resistor at r1, then tested it, i put it on the scope the tiny amount of ring i saw on the screen was too small to mess with, it just worked.
andy will give you the finer details of construction, he asked me to spread the word, so he will pop in to answer questions no doubt.

[fotoguy]

Thank you sinclairuser. This forum is a treasure. A big thank you to Andy, your Surf PI 1.2 is a great project. Thanks to all the members for making this place informative and a joy to visit ( and yes it's gotten into my blood).
Carl, you did a nice thing for all of us, thanks!
Warm regards
fotoguy

[SVEN1]

I was reading the first post and looking at the pictures, and thought those look like Don's coil shells.
A bit lower, saw Don's post.


Don's coil shells are excellent, that's all I use on my PI's.

[langleylocator]

Really interested as I ordered a PI 1.2 yesterday. Can't wait soooo excited. Looking forward to any info I can as this will be my first build.been lurking for a week and think I have read every post several times to try and understand but its all Greek to me at the moment. Thanks to all who have spent time and effort in I'm sure it will save me a few headache's. Because I just know its going to work straight away!!!!

[sinclairuser]

just got back from cornwall, totally cleaned widemouth bay of metallic objects, i will post pics tomorrow as i'm shattered after driving 7 hours.
thanks,
ally.

[fotoguy]

Andy kindly shared that he uses 0.5 mm enameled wire and that he uses 24 turns for the Surf Pi and 29 turns for the Barracuda. Is the OD on Don's coil housing 9 inches? If I'm using the Coil Calculator correctly I get the following based on a coil diameter of 8.75inches
111 mm radius
0.5 mm wire
24 turns
382 mH
Does this look ~ about right?? I look forward to your hearing how your adventure at Cornwall went sinclairuser.
Best all fotoguy

[langleylocator]

Ye Ha just finished mounting all of the components on the board( Had to go to mapl**s to get the bloody diodes as they wern't in the bag when i actually had time to have a session ) could have been me or the kids or even the damm cat thats moved em AGGGHHHH. Any-hooo just about to start making up the wiring loom. Having loads of fun even if some of the darn bits are fiddly

[silverdog]

I was replying from my phone and from memory - I will have to check the wire I used

For guidance using the calculator , my original surfmaster coil is 254uH, and the Baracuda is 453uH

Adjust the number of turns to suit your housing and wire thickness

Andy kindly shared that he uses 0.5 mm enameled wire and that he uses 24 turns for the Surf Pi and 29 turns for the Barracuda. Is the OD on Don's coil housing 9 inches? If I'm using the Coil Calculator correctly I get the following based on a coil diameter of 8.75inches
111 mm radius
0.5 mm wire
24 turns
382 mH
Does this look ~ about right?? I look forward to your hearing how your adventure at Cornwall went sinclairuser.
Best all fotoguy

[sinclairuser]

finally found camera, so this is what i found,http://s1170.photobucket.com/user/xs...g.html?filters[user]=139747252&filters[recent]=1&sort=1&o=0

had real trouble finding these pics, and posting them, items were found with andy's pi coil, they came from varying depths, most notable was gold earring at 5",the spoon was about 10" i thought it was something good, but alas.
anyway now doubt that these coils work in the real world, well done andy and thanks.

[sinclairuser]

got some more info on these coils, shielded this time, want to do final tests in the morning to make sure the info is correct.
had a hell of a game getting this to work this time, but its not the fault of the coil, more tomorrow.

[sinclairuser]

the shielded versions work well, though lower in depth than the unshielded ones, but only by small amounts, the shield material is foil strip from what i understand, i was worried about falseing as i had had lots of problems with that as a shield on some pi coils.
on my coils now i only use graphite for this reason, but once i had played around with the cable connection, and shortened it, and also removed the shield from the barracuda(i had a thick foil shield on the barracuda fisher 1266x style), it worked and got back to its 12us setting i had with my own shielded coil, i could not get lower, however none of the "skittishness" i had seen with the unshielded coil was there.
the construction of the coils is as reported by me before, robust, clean the kind of quality expected from silverdog, the only thing remaining is real world depth tests, i was going to test that today but its been raining heavily all day, i will do that tomorrow and post results, if this coil is fitted to a barracuda and baum's two stage mod done to the pre amp we could well have something really good, if it works stable and detects what we need it to i dont think shorter depths is really a problem, even at 10 inches say, thats quite a depth to dig on a beach.
i cant wait to test these on the mini pulse.