Active Hall Effect

The Hall Effect sensor can sense each change in target movement, regardless of speed, from zero to 15 kHz frequency range, generating a steady pulse train of frequency proportional to target speed. Typically, each time a gear tooth (or any ferrous discontinuity) passes in front of the sensor the output changes state. This type of sensor is known as “P” type because it uses N-P-N transistor logic (as opposed to “N” type, which uses P-N-P transistor logic).

Key features to note are:

• Reverse voltage protection, to prevent damage if miswired
• Extended temperature range
• Wide range of supply voltage
• Two output options of Supply Tracking or TTL Compatible
• Rugged design meeting IEC 77 Standards (European Railroad Applications)

AI-Tek has 3 Series of Hall Effect Sensors: RH Series, DH Series and BH Series. Below is a quick reference chart of the features of each of the series.

Active Hall Effect Speed Sensors – What They Are and Why They Matter

Active Hall Effect speed sensors are precision devices that measure rotational speed by detecting changes in a magnetic field using a Hall effect element. Unlike passive sensors, they require a small external power supply but offer the advantage of generating a clean, consistent digital output signal across a wide speed range—including very low speeds, even down to zero (zero-speed sensing).

These sensors are essential when you need accurate, real-time speed monitoring regardless of shaft speed or environmental conditions. Their ability to provide a constant output signal makes them ideal for slow-speed applications, direction detection, and systems that must function in both dynamic and static states.

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The Technology in Brief

Inside an Active Hall Effect sensor is a semiconductor Hall element positioned near a rotating ferrous target (gear tooth or pole wheel) and a permanent magnet. As the target moves, each change in magnetic field alters the voltage across the Hall element. The integrated electronics then condition this signal into a square-wave or pulse output that can be directly read by control systems.

Key advantages include:

• Zero-speed capability – reliable output even when the shaft is stationary.

• Wide air-gap tolerance – easier installation and alignment.

• Noise immunity – stable, digital output unaffected by signal degradation over distance.

• Temperature stability – consistent performance in environments from extreme cold to high heat.

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AI-Tek’s Active Hall Effect Product Lines

RH Series

Designed for robust industrial use, the RH series offers zero-speed detection, rugged housings, and excellent resistance to vibration and shock. Available in multiple thread sizes and electrical configurations.

DH Series

Optimized for directional sensing as well as speed, making them suitable for conveyor systems, vehicle wheel monitoring, and machinery where rotational direction is critical.

BH Series

Compact, high-performance sensors for space-constrained applications, delivering reliable output in both standard and harsh environments.

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Key Applications – Water, Gas, and Military

Water & Utility Sector

• Flow turbine and pump monitoring – zero-speed detection ensures accurate flow rate calculations even at low or intermittent flow.

• Valve position and rotation monitoring – critical for automated control in water treatment and distribution.

Gas & Petrochemical Industry

• Pipeline compressor and pump control – continuous speed and direction feedback for safe, efficient operation.

• Explosion-hazard environments (HazLoc) – available in models designed for intrinsic safety.

Military & Defense

• Vehicle drivetrain monitoring – armored vehicles, naval propulsion, and rotor systems benefit from zero-speed capability and rugged design.

• Missile system ground support equipment – accurate rotational feedback under extreme environmental conditions.

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