How Magnetic Position Sensors Work: Non-Contact Operation with Spectra Symbol’s MagnetoPot

Author: David Marriott, Spectra Symbol CEO

A guide on our heavy-duty MagnetoPot for harsh industrial and DIY applications

At a Glance: The MagnetoPot Solution

The MagnetoPot is a sealed, externally contactless linear position sensor that functions electrically as a simple 3-wire potentiometer. It is purpose-built for demanding environments where dust, moisture, or repeated cycling cause traditional sensors to fail quickly.

Primary Benefits

Superior Environmental Isolation: An external magnet drives a sealed internal magnetic wiper through the housing, keeping the active sensing area fully protected (IP64-rated). This allows reliable operation in debris-heavy, splash-prone, or wet conditions — and enables sensing through non-ferromagnetic barriers such as tank walls without risk of water ingress or contamination.
Straightforward System Integration: It delivers clean analog output with no signal conditioning required. As a passive voltage divider, it provides absolute position feedback immediately on power-up — eliminating homing routines and simplifying integration with PLCs, microcontrollers, and industrial control systems.
Proven Long-Term Reliability: Rated for >1 million internal cycles, the MagnetoPot offers significantly better durability than exposed mechanical potentiometers in high-duty applications. While the internal wiper experiences friction, the external design prevents contamination-related failures that plague standard sensors.

For Serious Hobbyists & Makers

Excellent choice when your project involves wet, dirty, or outdoor conditions (e.g., rainwater systems, greenhouse automation, or sealed enclosures). It integrates easily with Arduino or Raspberry Pi using a low-cost neodymium magnet ($3–$5), delivering reliable analog readings without complex electronics.

Core Specifications

Output: Analog (0–100% of supply voltage), absolute position
Environmental Protection: IP64 on active area (debris-proof and splash-proof)
Life Expectancy: >1 million cycles (internal wiper)
Hysteresis: Nominal 3 mm (magnet-dependent)
Integration: Passive 3-wire voltage divider (10 kΩ standard)
Common Applications: Liquid level monitoring (external mounting on tanks), hydraulic/pneumatic cylinder position feedback, harsh-environment machinery, and rugged DIY builds

Introduction: The Challenge of Measuring Motion Without Contact

Magnetic position sensors excel at providing precise measurement while withstanding the abuse of the environments they operate in. Without an external wiper, they can keep going for many cycles despite grime and slime.

In the family of our magnetic position sensors, MagnetoPot is a tank built for the roughest places.

What Is a Magnetic Position Sensor?

A magnet rides on the moving object; a stationary sensor reads its position via magnetic field changes. Hall-effect sensors need extra circuitry; Reed switches give only on/off. The MagnetoPot is passive and delivers smooth, continuous analog feedback across the full stroke.

Key advantages:

Externally non-contact
Sealed against contaminants
Works through non-ferrous barriers

How the MagnetoPot Differs from Traditional Options + Quick Decision Matrix

Traditional pots use a mechanical wiper—simple but wear-prone in dust or high-cycle use.

The MagnetoPot keeps the same 3-wire voltage-divider behavior while staying externally contactless: an internal magnetic wiper is dragged by your external magnet through a sealed acrylic track.

Quick Decision Matrix (choose based on your needs):

Sensor Type	External Contact?	Output	IP Rating	Life	Best For	Approx. Cost
Standard Pot	Yes	Analog	None	Low	Clean, low-cycle	$5–15
Reed Switch	No	On/Off only	Good	High	Simple end-stop detection	$2–8
Hall-Effect	No	Analog/ Digital	Varies	High	Precision, needs electronics	$10–40
MagnetoPot	No	Analog	IP64	>1M cycles	Dirty/wet + easy integration	$24–107

For contact-based membrane pots, see Spectra Symbol’s ThinPot™ & SoftPot™.

How the MagnetoPot Actually Works

Built on polyester, fiberglass (standard), or Kapton (high-temp) circuit with a sealed acrylic track.

Contains a sealed internal magnetic wiper.
Your external magnet attracts and drags it along the inside.
The wiper bridges the resistive element and collector trace, creating a voltage proportional to position.

No holes in the housing → fully sealed (IP64). Output is identical to any 3-wire pot.

Quick Specs

Resistance: 10 kΩ standard (20 kΩ for >300 mm); custom 5–500 kΩ (±20%)
Power: 0.5 W continuous, 1 W peak
Linearity: ±5% standard (±1% optional)
Resolution: Effectively infinite (analog); depends on your magnet
Life: >1 million cycles (internal wiper)
Hysteresis: 3 mm nominal (magnet size/strength/distance affects it)
Actuation: 0.09–0.11 lbs pull force (easy to test with a digital force gauge on a steel plate)
Temp: –40 °C to +85 °C (Kapton higher)
Travel: 8–1200 mm effective

Hobbyist Tip: For Arduino, use a ½-inch neodymium cube magnet at 3–8 mm gap. Code example: analogRead(pin) gives direct 0–1023 position.

Electrical Behavior and System Integration

No signal conditioning required. Absolute position on power-up—no homing. Plugs straight into microcontrollers, PLCs, or even a simple voltmeter.

For wiring diagrams, see the Potentiometer Wiring & Pinout Guide or the MagnetoPot datasheet.

Mechanical Design Considerations

Align the external magnet parallel to the track.
Keep proper gap for the 0.09–0.11 lb pull force.
Expect 3 mm hysteresis from internal wiper friction when direction reverses.
Never mount on steel/iron—it shunts the magnetic field and creates dead zones.

Smooth motion = best accuracy.

Industrial & DIY Applications

Liquid Level Monitoring: Mount on the dry outside of a tank; magnet float inside tracks perfectly (hundreds of oil & gas installs).
Hydraulic/Pneumatic Cylinders: Full-stroke feedback instead of just Reed-switch end-stops.
Harsh Machinery & Robotics: Survives dust, splashes, or outdoor weather.
Hobby Projects: 3D-printer bed leveling, CNC axis monitoring, or automated greenhouse float valves.

Caveats and Design Tradeoffs

Greatest strength: IP64 environmental isolation (externally contactless).
Internal wiper still experiences friction → rated >1 million cycles (not “zero wear”).
Choose magnet carefully; avoid ferromagnetic mounting surfaces.
Hysteresis (3 mm) is normal and magnet-dependent.

Stock units ship immediately; custom lengths/configurations typically 6–8 weeks.

Conclusion

The MagnetoPot gives reliable position sensing without external mechanical wear, combining classic pot simplicity with real-world sealing. Whether you’re prototyping on a weekend or specifying for industrial hydraulics, it delivers absolute analog output, IP64 protection, and easy integration.

By using an internal magnetic wiper driven through the sealed housing by an external magnet, the MagnetoPot achieves excellent environmental durability while retaining the straightforward voltage-divider behavior engineers and hobbyists already understand. This makes it especially valuable in applications where dust, moisture, or repeated cycling would quickly destroy a traditional potentiometer.

Explore the full MagnetoPot product page, shop models, or download the datasheet for detailed specs and dimensions. Need a custom version? Contact Spectra Symbol for fast help.