Rectangular coil

[Wirechief]

First I want to say hi to Eric, Al, Mr.Bill, Reg and others that I'm not able to recall right now. I hope everyone had a Merry Christmas and the New Year is starting out great! Has anyone of you ever built a rectangle coil for PI use?, and what effect if any do the corners have on the performance of the coil? Is depth not as good as a round or elliptical coil? has anyone ever built a triangular coil also? Thanks guys for any input and I hope all is well with you Al.

John T., CET

 

[Prospector Al]

Hi Wirechief,

A very Happy New Year to you! Rectangular coils are used almost exclusively in industrial application, like the monitoring of conveyor belts--I have built many of them.

The projected field is not as effective as that of a circular coil, so to get an idea of what the field distribution is, it's wise to
use a search coil to plot the field strength.

The simplest method is to use an audio generator and amplifier at a few kHz and simply measure the signal on an oscilloscope, as a function of the distance from the coil.

For a rectangular coil, the horizontal distance from the center is also of interest...

Best Regards,

Prospector Al

 

[Anonymous]

I have 2 coils that are square, one is 15", and the other is 25" and they are made from PVC and a little heavy. They have good depth-I got them for large objects that are deep; I used them for artillery projectiles in salt zones, but unfortunately they will still hit small shallow objects. Eric tells me it is possible to build an orthongal loop, like a pipe locator, which will not pick up the small stuff. But so far no one has built one.