Basket Coil

[Andi68]

With an insulation between the winding layers or the cross-winding technique, this is much easier to achieve

[dime196604]

@ dime196604
Glad to hear the test worked for you but sorry to hear the self shielding coil is a dud. Did you measure it's inductance and resistance?
At least the bundle coil is OK - these are a bit easier to fit into a housing too.

It was about 350uh if i remember correctly. I'm positive i just kept following the patter the whole way. I never advanced the wire one space, like your supposed too after so many turns. Ill try again sometime but for now i just wanna put it all together and use it. My wire bundle coil is only 200uh. And thicker gauge wire than i thought would work. Not sure exact size but its about three times as thick as the inner wires of cat 5 cable.

[baum7154]

Hello all, I believe you are discussing my posting on the 3DSS racetrack coil. Sorry that I have not been on the forum for some time now but I do try to check in occasionally. The 3DSS Coil geometry was originally used in the 1930 era as near as I can tell. However it was used as a radio receiver antenna and its self shielding characteristics were apparently not understood. A properly constructed coil correctly connected will not ‘see’ your hand grasping it with the detector set to about 10us delay. Too bad about the miswound coil. This coil is the only mono coil I wind as it is inherently faster than all other configurations with their required additional shielding in place.

Regards,

Dan

[dbanner]

Hello all, I believe you are discussing my posting on the 3DSS racetrack coil. Sorry that I have not been on the forum for some time now but I do try to check in occasionally. The 3DSS Coil geometry was originally used in the 1930 era as near as I can tell. However it was used as a radio receiver antenna and its self shielding characteristics were apparently not understood. A properly constructed coil correctly connected will not ‘see’ your hand grasping it with the detector set to about 10us delay. Too bad about the miswound coil. This coil is the only mono coil I wind as it is inherently faster than all other configurations with their required additional shielding in place.

Regards,

Dan

Is it inherently faster than a flat spiral coil also? All other things being equal of course. I have constructed a few coils using template and it worked fine, but I think it is laborious work. Making just the template is quite a chore in itself. I abandoned it in favor of flat spiral coil, just a bit easier wound. For the beach wet sand I favor bundle type coil. Also, while inter wire capacitance was reduced, I had suspicion that template was acting like some plate or core, increasing capacitance. But I had no way of removing it after the coil was wound so I could not tell what difference it makes. I used Plexi. For rigidity.

[geoscash1]

Is it inherently faster than a flat spiral coil also? All other things being equal of course. I have constructed a few coils using template and it worked fine, but I think it is laborious work. Making just the template is quite a chore in itself. I abandoned it in favor of flat spiral coil, just a bit easier wound. For the beach wet sand I favor bundle type coil. Also, while inter wire capacitance was reduced, I had suspicion that template was acting like some plate or core, increasing capacitance. But I had no way of removing it after the coil was wound so I could not tell what difference it makes. I used Plexi. For rigidity.

Ive built about a dozen and have used everything from cardboard from a new shirt to .125 lexan and they all are the same no matter which of the detectors ive built so in my personal opinion it makes zero difference whats used for the form.

[dbanner]

OK, can you say what is maybe the best wire to use, I mean what size wire. I want to try a dual field arrangement of basket type. What wire you recommend? I was thinking anything between 0.4mm and 0.6mm. enamel copper. Here is an older one I made some time ago. I used cardboard on this for template. It work very good.

[geoscash1]

OK, can you say what is maybe the best wire to use, I mean what size wire. I want to try a dual field arrangement of basket type. What wire you recommend? I was thinking anything between 0.4mm and 0.6mm. enamel copper. Here is an older one I made some time ago. I used cardboard on this for template. It work very good.

In my coils, I tested different wire. I couldnt tell you the best but out of all the wire types I used but 250/46 dual layer litz gave the best results, 175/44 dual layer litz was second best and the 7 strand plated teflon followed. The enamalled copper was the worst of the bunch as far as performance.

One thing for sure, you dont want to fill the space between the wire on the 3dss with epoxy. You should leave it as the open air design it is. Your coil pics looked nice but it was hard to tell if the epoxy you used filled the void or air space between the wire wraps.
I have used coil forms from Don (dbowers here in the forum) to house the coil on its form. Just used plastic standoffs to mount it in the shell, no epoxies, then sealed the coil shell. Hope that helps.

This is the seller I get my litz from. You can message him and he will usually get you the length you want.
Ebay seller:mkmak222

[dbanner]

Thanks very much, appreciated.

[geoscash1]

Thanks very much, appreciated.

Your welcome..

[baum7154]

Is it inherently faster than a flat spiral coil also? All other things being equal of course. I have constructed a few coils using template and it worked fine, but I think it is laborious work. Making just the template is quite a chore in itself. I abandoned it in favor of flat spiral coil, just a bit easier wound. For the beach wet sand I favor bundle type coil. Also, while inter wire capacitance was reduced, I had suspicion that template was acting like some plate or core, increasing capacitance. But I had no way of removing it after the coil was wound so I could not tell what difference it makes. I used Plexi. For rigidity.
----------------------------------------------------------

Hi banner,

I know that unshielded spiral can be very fast, perhaps the fastest of all coil winds...unshielded.

Yes the 3DSS is faster than a spiral coil when the spiral coil is properly shielded with graphite etc. The added capacitance that the required additional shield contributes slows the spiral coil down. 3DSS does not require an additional shield due to its unique geometry.

Happy New Year

Dan