Different Coils ID Problem

[Daves]

Hi,
What should I do to avoid ID problems when I use a different coil (bigger or smaller)? How should I produce the coil or what algorithm should I use? For this,
I am waiting for your suggestions in terms of analog and digital.

[Altra]

Just make the inductance and resistance the same for each size coil. That's how it is done by commercial detector manufactures.

[Daves]

Just make the inductance and resistance the same for each size coil. That's how it is done by commercial detector manufactures.

Even though the inductance is the same, it changes.

[Altra]

Without details on your project it is impossible to know whats happening. What kind of coil are you using, commercial, Homemade?

[Carl-NC]

Normally, detectors are not incredibly sensitive to changes in the coil inductances. They will usually tolerate +/- 10% with little effect on the TID. If you are seeing differently then I would need to know design details.

[Daves]

Normally, detectors are not incredibly sensitive to changes in the coil inductances. They will usually tolerate +/- 10% with little effect on the TID. If you are seeing differently then I would need to know design details.

Carl, what procedure should be followed when using a different search coil? The default incoming signal levels in different search coils will be different and the raw phase initial value will be different, so different degrees of ground adjustment need to be made according to the raw phase. How will we know if a different coil is installed and what procedures should we do?

[Carl-NC]

If you look at just the idle null of the coil, the phase can be somewhat random. But when you apply a ferrite to the coil, the RX phase should be very consistent, hopefully very close to 0° ignoring the phase shift of the preamp. If your ferrite phases differ more than 2° or so then something is wrong.