Description:
Hall-effect sensors are commonly used for measuring the speed of rotating assemblies where a magnet on the assembly alternately makes and breaks magnetic contact with the sensor as the assembly rotates.  They can also be used for applications such as determining when a door has been opened, position sensing and detecting the magnetic field created by current flow in a wire.

Features
4.5V to 24V DC operation voltage
Open-Collector pre-driver
25mA maximum sinking output current.
Reverse Polarity Protection

Applications 
Speed measurement
Home appliances
Position detection
Flow measurement

Absolute Maximum Ratings （TA=25℃）
Supply Voltage VCC··············4.5-24V
Operating Temperature Range TA ···········-40～85℃
Output Current IO···················25mA
Storage Temperature Range TS ················-55～150℃

Package included:
10pcs OH137 OH 137 Linear Hall Effect Magnetic Unipolar Sensor Switch IC for Arduino