Basket Coil

[dime196604]

So i started building a Surf PI about two years ago, and i made a racetrack shape basket coil for it. I had issues and the project got put on hold for a long time. My problem is i made the coil and it is all cemented up, but i did not mark what wires were the inside start of the coil or the outside end. Is there any way to figure out what wires are what? I believe with a basket coil it matters what coil wire goes to ground(could be wrong here)

[qute1]

um hook it up and see (the surf is very resilient just don't run it without the coil hooked up at all ), literally try it then swop them over and if you get better result one way then stick with it! so long as any shielding goes to ground it will not hurt just suck it and see. best of luck..

[dime196604]

Thanks for the reply. The other reason i ask is because the coil i made is a design i found on this forum. Don't remember the post or who did it. But he called it the self shielding racetrack coil. So the coil shields its self, that's the reason for needing to know what wires are what. But i will try both ways and see what happens.

[qute1]

good luck you really can't break anything just play with it it'l be fine.

[Goaty]

But he called it the self shielding racetrack coil. So the coil shields its self, that's the reason for needing to know what wires are what.

This video link was posted a while back in relation to non-electro cap shielding testing and the technique shown using a CRO may work with your coil too.

https://www.youtube.com/watch?v=BnR_DLd1PDI

If you have a CRO it may be worth a try - would be interested to hear how you get on.

[Goaty]

Well, I had a bit of time to spare yesterday, so I quickly knocked up a 3DSS coil and connected it to the CRO to see if there was any difference .


My CRO is a 20MHz analogue type and I set the vertical gain to 50mV/div and the sweep to 50uS/div.


To induce some signal into the coil I simply place my hand on it wile it was laying on the bench.


As can be seen from the photos, the amplitude of the noise was much higher with the coil connections reversed than ‘correct’ (shield to shield) so it would appear that this method should work to check a self shielding coil once it is sealed up.


P.S. Dime - you are not the only one who has glassed up one of these coils and lost the lead identification.

[qute1]

Yeah cure and be damned

[dime196604]

Goaty, thanks for the help. I will try that one tonight when i get home form work.

[Goaty]

I will be interested to hear how you get on

[dime196604]

Goaty, that worked with the scope. Coil did do too well. Wouldn't detect anything past about 4in. I think i got the weaving of the coil wrong. I just read parts of article built the coil without knowing how to do it proper. I've read more about it and am sure i skipped some steps. I will try again sometime, but I'm getting about 14in on a US Penny now with my mono wire bundle coil, so I'm happy with it for now.

[Andi68]

A basket spool is crafts for housewives.

No detector manufacturer builds basket coils

[Goaty]

@ 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.

[kt315]

A basket spool is crafts for housewives.

No detector manufacturer builds basket coils

still no, but they are monitoring the forum constantly! ie they will make and will close off by a patent - SIC!

minelab will be FIRST!

[Andi68]

I don't believe that

[Hyena]

I don't believe that

I just hope believing will be enough to stop them