1. A3144 SENSITIVE HALL-EFFECT SWITCHES & AH3503 503 Linear Hall sensor
TYWu

2. Hall Effect
VH = I * B / (n * e * d)

3. Theory
The Hall switch is characterized by the magnetic switching points BON (or BOP ) and BOFF (or BRPN).

4. Theory
If the magnetic flux exceeds BON , the output transistor is switched on; if it drops below BOFF, the transistor is switched off. The magnetic hysteresis BHYS is the difference between the switching points BON and BOFF.

5. Pins
Pinning is shown viewed from branded side

6. Electrical Characteristics
At VCC = 8 V over operating temperature range.

7. Electrical Characteristics
Each device includes a voltage regulator for operation with supply voltages of 4.5 to 24 volts
Reverse battery protection diode
Quadratic Hall-voltage generator
Temperature compensation circuitry
Small signal amplifier, Schmitt trigger, and an open-collector output to sink up to 25 mA. With suitable output pull up, they can be used with CMOS logic circuits

8. A3144.pde int sensorPin = 2; int counter = 0;
boolean sensorState = false;
void setup() {
Serial.begin(9600);
pinMode(sensorPin, INPUT);
// Pull Up
digitalWrite(sensorPin, HIGH); }

9. A3144.pde void loop() { if(magnetPresent(sensorPin) && !sensorState)
sensorState = true;
printMessage("Magnet Present"); }
else if(!magnetPresent(sensorPin) && sensorState)
sensorState = false;
printMessage("Magnet Gone");

10. A3144.pde void printMessage(String message) { counter++;
Serial.print(counter);
Serial.print(" ");
Serial.println(message); }
boolean magnetPresent(int pin){
return digitalRead(pin) == LOW;

11. Connection
Figure

12. Execution
Snapshot

13. AH3503 503 FEATURES Extremely Sensitive Flat Response to 23 kHz
Low-Noise Output
4.5 V to 6 V Operation
Magnetically Optimized Package

14. AH
Pins

15. AH
Block Diagram

16. AH
Electrical Characteristics

17. AH
Operation
The output null voltage (B = 0 G) is nominally one-half the supply voltage.
A south magnetic pole, presented to the branded face of the Hall effect sensor will drive the output higher than the null voltage level.
A north magnetic pole will drive the output below the null level.

18. Applications
Notch Sensor, etc.

19. Experiment https://www.youtube.com/watch?v=bnOd8f5Vev0

20. Experiment ?
Arduino

21. Experiment
Arduino
const int hallPin = 0; // the hall effect sensor pin
const int ledPin = 11; // the LED pin
int volt;
void setup() {
pinMode(ledPin, OUTPUT);
pinMode(hallPin, INPUT); }

22. Experiment void loop(){ int luminance; volt = analogRead(hallPin);
luminance = 0.5*abs(volt-512)-1; //volt=0~255
analogWrite(ledPin, luminance); }