Magnet wire coil

[Tinkerer]

The depth is relative to the diameter of the TX coil. In the case of a narrow coil, it is the narrow width that defines the depth.
The oOo coil reduces the ground response, but is sensitive to tilt. Therefore the user needs to be careful the keep the coil parallel to ground.

[green]

Making another coil. Cut 20mm off each side of the 200mm ID round form and the race track coil form that went over them. Question. What is the correct name for the two coils? Two Rx 200mm ID, Tx race track and two Rx trimmed, Tx race track. Lose some signal but they reject ground, noise and EF. The round Rx is better with target over 100mm away. The trimmed is better less than 100mm away.

Why isn't the o0o or figure 8 (what ever it's called) coil used more often since it cancels or at least reduces ground signal, noise and EF? Might still need to take a GEB and EF sample. Damaged the o0o narrow. Want to make another narrow and wide o0o coil. Need to reduce Tx resistance. Thinking of twisting 2 to 4 strands of the awg 28 and then winding the Tx coil. Charted the last o0o wide coil I made. The response at each end is is similar to a round mono coil with a sharp null in the center that looks like it could be used to pin point. I made a Heath kit probably 50 years ago. Used it to find arrows that were buried in the grass when we missed the target so I have little experience metal detecting. With help from ITMD, GEOTECH forum and Eric Fosters PI tech forum I'm learning something about PI metal detectors. The o0o coil is the same as the narrow but with round Rx coils and a wider race track coil.

[green]

Hi Green in post #28 are the toothpicks removable ?

Yes. At first they weren't. After I added the beads I can.

[6666]

Hi Green in post #28 are the toothpicks removable ?

[6666]

Outside, about 180mm x 450mm

Thanks Green

[green]

Whats the size of your new coil ? thanks

Outside, about 180mm x 450mm

[6666]

Whats the size of your new coil ? thanks

[green]

Making another coil. Cut 20mm off each side of the 200mm ID round form and the race track coil form that went over them. Question. What is the correct name for the two coils? Two Rx 200mm ID, Tx race track and two Rx trimmed, Tx race track. Lose some signal but they reject ground, noise and EF. The round Rx is better with target over 100mm away. The trimmed is better less than 100mm away.

[Chet]

Hi Green

I like the results that you got with the Co-planar coil with the bucking coil. Aziz's analysis (link below) indicates that a larger diameter receiver coil might improve the iffy results at 12".

Thank you again for the information,
Chet

http://www.geotech1.com/forums/showthread.php?14121-New-Concentric-Co-planar-Coil-with-Strong-MF&p=151864#post151864

[green]

Hi Green

Great work as usual. How many turns and uH in your coils?

Thank you,
Chet

Tx_ 23T, 295uh, 8 inch ID, RX_ 37t, 290uh, 4 inch ID, buck_10T, 26.4uh, 4 inch ID. Started with 7T on the buck, had to add some due to coupling and a smaller average diameter.

[Chet]

Hi Green

Great work as usual. How many turns and uH in your coils?

Thank you,
Chet

[green]

First try at a concentric coil. Charted without shield. Think the data makes sense, maybe not. The output at 12 inches with the concentric is a little iffy with only 1 or 2 counts. Maybe it's a coplanar coil.

[Chet]

Hi Green

Great comparison charts.

Chet

[green]

Compared some coils. 8 inch is the inside dimension. DOD Rx coils adding. oOo Rx coils subtracting. Target US nickel.

[Chet]

Hi Green

It certainly does have a very defined null at the center. Very interesting measurements.

Thank you,
Chet