If you’ve followed our gaming-related teardowns over the previous years, you probably know that we have strong opinions when it comes to joysticks. Time and time again, we’ve taken apart controllers from different manufacturers, only to be disappointed to find old-school stick design, aka potentiometers, in even the most futuristic gaming hardware.
That’s because potentiometers come with a fatal flaw, a failure that’s not a matter of “if” but “when.” A thin metal wiper in the joystick scrapes back and forth across a printed carbon film resistor. Tilt the stick, and the wiper slides along the track, changing resistance and voltage and moving your character across a screen. There are lots of ways this system can fail: Maybe the sensors themselves wear down. Maybe the spring fatigue. Maybe the plastic stretches. Maybe grime or plastic dust blocks the sensors. Whatever way it happens, all that physical contact with the wiper naturally takes its toll.
Going Contactless
So if physical contact is the enemy, the fix is obvious: go contactless. Wireless is clearly the way forward for sensing. Instead of a wiper scraping across a track, a small magnet is mounted to the joystick shaft and a sensor chip is placed on the circuit board below. Tilt the stick, the magnet moves, the sensor reads the changing magnetic field, and the controller knows where you’re going.
That’s why we’ve been pretty vocal about Hall-Effect joysticks being the future, even if they are decades-old technology. We stocked them. We recommended them. We wrote a whole wiki page about how they work. But recently, you may have noticed something: by now, there are more TMR stick options in our store than Hall-Effect ones. So what’s TMR and why is it replacing Hall-Effect in stick tech?
Enter: TMR
TMR stands for Tunnel Magnetoresistance. The setup is the same as Hall-Effect, it’s all about them magnets. However, inside the sensor chip, something fundamentally different is happening. Instead of measuring a voltage from deflected electrons, a TMR sensor measures how easily electrons can quantum tunnel through an impossibly thin wall, depending on which way a magnet is pointing.
Yes, quantum tunnel. As in, one of the strangest phenomena in physics is now doing the work inside your joystick. Let’s tunnel in.
The Quantum Part (Stay With Us)
In the everyday world you and me inhabit, walls are walls. Throw a ball at a barrier, and if it isn’t strong enough to get through, it bounces back.
Electrons don’t play by those rules. At quantum scales, particles behave like waves. And when one of those waves hits a barrier, it doesn’t just stop. It fades through, getting weaker as it goes. If the barrier is thin enough—about 1 to 2 nanometers—there’s a real chance the electron appears on the other side. It didn’t go over. It didn’t punch through. It leaked through, like a ghost walking through a wall. Spooky!
Here’s what makes this useful: not all electrons tunnel equally. How easily they get through depends on a quantum property called spin.
You Spin My Electrons Right Round, Right Round
Every electron carries an intrinsic magnetic property called spin, think of it as a tiny internal compass that points either “up” or “down.” In magnetic materials like the iron-cobalt alloys used in TMR sensors, more electrons spin one way than the other. This imbalance—spin polarization—is the basis of its sensing technology.
A TMR sensor is built around a nanoscale sandwich called a Magnetic Tunnel Junction. Three layers, each a few atoms to a few nanometers thick:
- Pinned Layer (magnetic film locked in one direction). This is your reference point.
- Tunnel Barrier (ultra-thin magnesium oxide). The wall through which electrons tunnel.
- Free Layer (magnetic film that rotates to follow whatever external magnetic field is nearby). This is the part that moves when you move the stick.
The best analogy is polarized sunglasses. Take two pairs and stack the lenses. Align them the same way, and light passes through easily for a clear view. Rotate one pair 90°, and everything goes dark.
In a TMR sensor, the “polarization” is the electron spin direction. When both magnetic layers point the same way, electrons tunnel through the barrier easily—low resistance. When they point opposite ways, electrons get blocked—high resistance. And the resistance changes smoothly with the angle between the layers, so you get a clean, continuous signal as the joystick moves.
That leads to the following construction: Mount a magnet on a joystick shaft. Tilt the stick. The magnet rotates the field at the sensor. The free layer follows. The resistance shifts. The chip knows where you’re pointing. Use two sensors and you have X and Y axes handled.
That’s TMR. Quantum tunneling modulated by electron spin, translated into a joystick position reading. Nobel Prize-related physics for gaming.
Why This Makes TMR The Better Choice
A Hall-Effect sensor produces a tiny signal. We’re talking microvolts. It’s like trying to hear someone whisper across a noisy room. The signal needs to be amplified, and that amplification costs power, adds noise, and is sensitive to temperature changes.
A TMR sensor, measuring the same magnetic field, produces a significantly stronger signal. Continuing the same analogy: Now the person is talking at normal volume right next to you. You can hear them just fine without cranking the gain.
That strength translates to improved precision, power draw, and magnetic interference resistance. TMR gives you a cleaner, more stable signal, leading to tighter dead zones, lower jitter, and less noise. GuliKit specs their TMR sensors current consumption at 0.1-0.3 milliamps versus 0.5-2 milliamps for a linear Hall sensor. For wireless controllers, that means real (if modest) battery life gains.
Last but not least, TMR sensors don’t get confused by the additional magnets that are commonplace in modern controllers—think haptic motors and trigger magnets. During our Switch 2 teardown, we noted that Hall-Effect sensors might not pair well with the new magnetic rail attachment. TMR handles stray fields much better.
TMR Is DIY For Now
There are a lot of arguments for TMR sticks. The technology is moving: Valve’s upcoming Steam Controller uses TMR, ASUS partnered with GuliKit on official TMR replacement modules for the ROG Ally, and a growing number of third-party controllers ship with TMR out of the box.
And yet—as we confirmed in our Switch 2 teardown—none of the three major console manufacturers have adopted either TMR or Hall-Effect. The best joystick sensing technology available today is exclusively in third-party controllers and aftermarket replacement parts.
That means that if you want TMR in your DualSense controller or your Joy-Cons, the only way to get it is to open the controller and put it there yourself. That’s what our GuliKit TMR replacement modules are for. Turns out the future is here, and the power of quantum tunneling is literally in your hands.
3 Comments
Sweet! These big name brands really need to get on point with this! Appreciate your article.
Shawn Cohen - Reply Share
As an end user, my big question is this: Can these be used as a drop-in replacement for old school Pot sticks or does the board need to be designed for them specifically?
James LaLone - Reply Share
Yeah, they can! GuliKit has designed TMR sticks for specific controllers to serve as a drop-in replacement. For Xbox and PlayStation controllers, the stick replacement process unfortunately requires a bunch of soldering, but in the case of Switch Joy-Cons, the replacement is relatively straightforward. They do require calibration after installation, though!
Manuel Haeussermann - Share