A Few Unusual Questions — Looking for Some Advice ！ ：）

[Allen KE]

Hi everyone at Geotech!

I'm currently working on a personal project that combines a metal detector with an RC vehicle. I've run into a few technical challenges along the way, and I'm hoping to get some advice or ideas from the community.

Shielding and Interference Issues

This has been a bit of a tricky problem for me.

The search coil is mounted underneath the vehicle, but there are motors, sensors, and other electronic components nearby that can interfere with it.

Ideally, I'd like the coil to be mainly sensitive to what's underneath it (toward the ground), while minimizing interference coming from the sides and above.

I've been looking into shielding materials for VLF metal detectors, particularly mu-metal (permalloy). However, when I bought some and placed it near the coil, the shielding material itself seemed to interfere with the detector's performance. That left me a little confused.

I also tried moving all the electronic components further away from the coil, and that actually worked pretty well. Unfortunately, it made the vehicle much larger than I'd like.

To keep the vehicle compact and easy to transport, I'm trying to fit everything within 600 mm × 500 mm.

For reference, I'm currently using a 9.8-inch search coil.

Has anyone here dealt with a similar issue? I'd really appreciate any suggestions on shielding techniques, materials, or coil placement that might help reduce interference without making the vehicle too large.

Thanks in advance for any advice!

[GeoMax]

Hi,
There's too much metal visible in the pictures. The yellow supports are definitely metal, as is the white plate in front of the front axle. I'd replace those with non-metallic material first. Then, get rid of the LED strips for now. What kind of detector electronics are you using in your project? Any well-known circuits?

[Allen KE]

Hi, Guru.

Thank you for reply.

Sorry that I forgot to explain some of the vehicle's components.

The yellow parts are made of fiberglass. Although fiberglass is slightly heavier than carbon fiber, it's much more affordable and doesn't interfere with the metal detector.

The white section you mentioned is actually the rear of the vehicle. The vehicle uses a front-wheel-drive system, with power delivered to both front wheels.

The black and white parts you see are currently 3D-printed using carbon-filled materials. The front and rear wheels are the only components that contain metal.

I've already ordered some wheels with plastic rims and tires without steel reinforcement. These should help further reduce interference with the metal detector.

As for the search coil, I'm currently using one from an unknown brand, while the circuit board is something I designed and built myself.

[moodz]

The real question is .....what sort of targets, ground and depth are you working with.

[boilcoil]

An induction-balanced system of the coaxial type (Rx-Tx-Rx) is the least sensitive possible to interference and targets located to the sides of the coils.