the KY-003 uses a digital Input
A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications.
In its simplest form, the sensor operates as an analog transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced.
The KY-003 is a Hall effect sensor. If no magnetic field is present, the signal line of the sensor is HIGH. If a magnetic field is presented to the sensor, the signal line goes LOW, at the same time the LED on the sensor lights up.