AH3503 — Linear Analog Hall Effect Sensor (TO-92)
A ratiometric analog voltage output sensor for magnetic field measurement, RPM sensing, BLDC motor commutation, e-bike throttle systems, and robotics applications. Compatible with Arduino, ESP32, and Raspberry Pi ADC inputs out of the box.
- Linear Analog Output
- Ratiometric (VCC-tracking)
- Bipolar Field Detection
- Arduino Ready
- ESP32 Compatible
- Raspberry Pi via ADC
- −40°C to +85°C
- 0.1V – 4.9V Output
The AH3503 outputs a continuous voltage proportional to magnetic field strength. With no magnet present the output sits near half the supply voltage (~2.5V at 5V). For a simple on/off trigger use a Hall switch such as the AH3144.
Electrical & Physical Specifications
Full datasheet specifications for the AH3503 linear Hall Effect sensor (model AH3503, TO-92A package). All electrical values at 5V supply unless stated.
- Model Number
- AH3503
- Output Type
- Linear Analog (Ratiometric)
- Supply Voltage (VCC)
- 3.5V – 6.6V DC
- Output Voltage Range
- 0.1V – 4.9V (at 5V supply)
- Zero-Field Output
- ~2.5V at 5V supply (VCC ÷ 2)
- Sensitivity
- 15.25 mV/mT typical at 5V
- Linear Magnetic Range
- ±80 mT (bipolar — north & south)
- Package
- TO-92A, 3-pin, 1.27mm lead pitch
- Operating Temperature
- −40°C to +85°C
- Active Sensing Face
- Flat (printed) face of TO-92 body
- MCU Compatibility
- Arduino, ESP32, Raspberry Pi (via ADC)
Output scales with supply voltage. At 3.3V (ESP32), zero-field output is ~1.65V. Always calibrate at your actual VCC for accurate readings.
Pinout & Wiring Instructions
Hold the AH3503 with the flat (printed) face toward you, legs pointing down. Pins are numbered 1, 2, 3 from left to right.
AH3503 Pinout
1 VCC • 2 GND • 3 OUT
-
1Orient the sensor
Flat face toward you, legs pointing down. Pins 1–3 run left to right.
-
2Pin 1 → VCC
5V for Arduino Uno; 3.3V for ESP32 or Raspberry Pi.
-
3Pin 2 → GND
Common ground rail of your circuit.
-
4Pin 3 → Analog In (A0)
Read with
analogRead(A0). Returns 0–1023 on a 5V Arduino. -
5Calibrate zero field
No magnet ≈ 512. Above 512 = north pole. Below 512 = south pole.
The flat face (the face showing the "503 118" label) is the active sensing surface. Point it perpendicular to your magnet for maximum sensitivity.
Applications & Use Cases
The AH3503 is used wherever a smooth, continuous analog signal is needed from a changing magnetic field — from motor control through to DIY Arduino magnetic sensing projects.
Count magnet passes per revolution for accurate motor, fan, or wheel speed measurement.
Smooth linear throttle control for electric vehicle drive systems and speed controllers.
Detect rotor position in brushless DC motors for precise electronic commutation timing.
Non-contact position sensing using a sliding or rotating magnet — no wear, no contact.
Joint angle sensing, gripper position detection, and servo arm control in robotics.
Direct analog input to Arduino A0 — no extra components or op-amp needed.
For higher precision, add a 100nF decoupling capacitor between VCC and GND close to the sensor pins and use analogReference(INTERNAL) on Arduino for a stable reference.
Frequently Asked Questions
- The AH3503 is a linear analog sensor. It outputs a continuous voltage proportional to field strength — not a simple HIGH/LOW switch. For on/off detection use a Hall switch such as the AH3144.
- Yes — Pin 1 to 5V, Pin 2 to GND, Pin 3 to A0. Use
analogRead(A0)to read 0–1023. Around 512 = no field, above 512 = north pole, below 512 = south pole. - Yes. Supply at 3.3V for ESP32 and connect OUT to any ADC pin (zero-field output ≈1.65V). Raspberry Pi needs an external ADC such as the MCP3008 as it has no built-in analog inputs.
- Approximately half the supply voltage — ~2.5V at 5V, ~1.65V at 3.3V. This midpoint is ratiometric and tracks VCC proportionally.
- The flat printed face (labelled "503 118") is the active sensing side. Point this face directly at your magnet for maximum sensitivity.
- Yes. The ±80mT range is fully bipolar — north raises the output above midpoint, south lowers it below. Ideal for absolute angle sensing with a diametrically-magnetised magnet.