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Crowtail- Magnetic Switch


This is a Crowtail interface compatible Magnetic switch module. It is based on encapsulated dry reed switch MKA14103. MKA14103 is single-pole, single throw (SPST) type, having normally open ruthenium contacts. The sensor is a double-ended type and may be actuated with an electromagnet, a permanent magnet or a combination of both. The magnetic switch is a wonderful tool for designers who would like to turn a circuit on and off based on proximity.

Model: CT009320S
Crowtail- Magnetic Switch.jpg


  • Crowtail compatible interface
  • Minimum external parts
  • 10W rating
  • Rugged encapsulation

Application Ideas

  • Proximity Sensor
  • Security Alarm Sensor
  • Level Sensor
  • Flow Sensor
  • Pulse Counter



Item Min Norm Max Unit
Working Voltage 4.75 5.0 5.25 V
Switched Power 10 10 10 W
Switched Voltage AC,RMS value(max) < 140 < 140 < 140 V
Switched Current DC < 500 < 500 < 500 mA
Carry Current DC < 0.5 < 0.5 < 0.5 A
Contact Resistance <200 <200 <200
Insulation Resistance >106 >106 >106
Operating Temperature -40 - 125
Operate Range 10 - 40 AT


With Arduino

1.The SIG pin of the module output LOW normally. When a magnet approaches the switch, the magnetic switch close and the SIG pin output HIGH. The following sketch demonstrates a simple application of using the Magnetic switch to control the led. When you put a magnet that has enough magnetic power close to the module, the switch is closed .Then the SIG pin out put a high voltage. You can use this to control the led. As the picture on the below indicates, the Magnetic switch is connected to digital port 2 of the Crowtail - Basic Shield and the LED is connected to digital port 5. When there is Magnetic approaches the switch, the SIG pin output a High voltage. Then the LED light. The hardware installation is as follows:


2.Copy and paste code below to a new Arduino sketch.

#define LED 5//the on board LED of the Arduino or Seeeduino

void setup()

void loop() 
    if(isNearMagnet())//if the magnetic switch is near the magnet?
void pinsInit()

/*If the magnetic switch is near the magnet, it will return ture, */
/*otherwise it will return false                                */
boolean isNearMagnet()
    int sensorValue = digitalRead(MAGNECTIC_SWITCH);
    if(sensorValue == HIGH)//if the sensor value is HIGH?
        return true;//yes,return ture
        return false;//no,return false
void turnOnLED()
void turnOffLED()

Then the LED light when there is Magnetic approaches the switch. Have a try!