How a metal detector actually works in simple terms

 

What’s Actually Happening Under Your Metal Detector? (And How to Find More Stuff)

So you're out there swinging a metal detector like a treasure-hunting Jedi, but have you ever asked: What’s this thing really doing? Like, how does it know there's a rusty nail down there? Or a coin? Or your future retirement in gold bars?

Let’s break it down—no science degree required.

The Coil: Your Detector’s Superpower

At the bottom of your detector is the coil—that big circle thing you wave around like you’re casting spells. But it’s not magic. It’s actually science. Here’s the basic deal:

• The coil sends out invisible magnetic energy into the ground.

• When this energy hits metal, it causes something called “eddy currents” in the object (fancy term for tiny electric swirls).

• Those eddy currents push back with their own magnetic vibes.

• Your detector senses that “pushback” and goes “BEEP!”

That’s it. That’s the moment you start digging like a pirate who’s found a clue.

Beep Breakdown: What the Signal Tells You

Not all beeps are created equal. Some are gold rings, and some are literal trash. (Looking at you, aluminum pull tabs.)

Here’s what your detector is picking up:

• How strong the signal is = how big or close the object is.

• The timing of the signal shift (called phase shift) = what kind of metal it probably is.

For example, silver and copper give a nice clean tone. Most detectorist refer to it as hightone. Iron? That’s the raspy, annoying buzz you start to hate. Better known as lowtone.

Coil Size Actually Matters. A Lot.

Think of your coil like a camera lens:

• Big coils = zoomed out. Great for deep objects and covering more ground, but might miss tiny stuff.

• Small coils = zoomed in. Perfect for finding coins between trash and hitting those sweet signals in tight spaces.

Also, coil shape matters:

• Round = old-school and solid

• Elliptical = slices through junky ground better

• DD = great for mineral-rich or salty soil

• Concentric = better at pinpointing

Moral of the story? The right coil can make or break your hunt. No shame in being a “coil collector.”

Coil Construction = Why Some Detectors Rock

Coils aren’t just loops of wire—they’re tuned like guitars. A well-made coil is:

• Built with just the right number of wire wraps (not too thicc, not too thin)

• Tuned to a specific frequency so it's super sensitive to certain metals

• Able to reject ground noise so you're not chasing rocks all day

Basically, cheap coils miss treasure. Good coils = gold (sometimes literally).

VLF vs. PI: Detector Tech 101

There are two main types of detectors, and here’s the “too long, didn’t study” version:

• VLF (Very Low Frequency): This is what most hobby detectors are. They’re great for identifying what’s under the soil and ignoring junk (sometimes).

• Pulse Induction (PI): These go DEEP and love beaches or salty ground. But they’re kinda like golden retrievers—very enthusiastic, not great at saying no to garbage.

If you're just starting out, VLF is your go-to. If you’re storming the beaches like a treasure trooper, go PI.

Tips for Getting Way Better Results

Okay, real talk: just owning a detector doesn’t make you Indiana Jones. But here’s how to actually get more beeps (good ones):

• Ground balance before you start. Every time. Seriously.

• Use headphones. You'll hear more signals and fewer birds.

• Go slow. Overlap your swings. Rushing = missing.

• Know your detector’s settings. Play with sensitivity, discrimination, and mode.

• Practice in your backyard. Bury coins and junk and see how they sound.

And don’t skip places just because they look trashy. That’s where everyone else gives up—and you swoop in for the win.

Final Thoughts (AKA Stuff You’ll Actually Remember)

Your detector coil is basically shouting “Hey, anything metal out there?” into the ground. If something answers back, it’s your job to figure out if it’s treasure or trash.

The more you understand the science—and how your machine reacts—the more stuff you’ll find. Less digging junk. More bragging rights.

So go out, swing smart, and remember: every beep is a maybe, but the right coil turns "maybe" into oh snap, it's a silver dime!

~Windy Digger

Robin Paul Paré

Rob is a passionate metal detecting enthusiast with a deep love for uncovering lost history. But for Rob, it’s not just about the finds — it’s about the people. He thrives on connecting with fellow detectorists, sharing knowledge, and building a strong, supportive detecting community. Whether he’s out hunting solo, organizing group events, or helping someone new get started, Rob is always ready to dig in and make a difference — one signal at a time.