This Site Requires Javascript!

ArduSensor Magnet Quickstart Guide


The Basics:


The ArduSensor Magnet is made up of a reed switch, a type of switch that closes when a magnet is nearby (within 1-2cm from the outer plastic).




First off, if you don’t know how to solder, go here to learn the basics so that you are thoroughly prepared to assemble your kit.


Parts in Kit:


Qtechknow ArduSensor Magnet PCB (Printed Circuit Board)

Reed Switch

10K Ohm Resistor - 1/4W

Male Headers (5)


Tools Needed to Assemble:


Soldering Iron

Rosin Core Solder

Safety Glasses

Safety Mask

Vice or Third Hand


You will need to get on your own:


Arduino Leonardo with micro-B USB Cable


Arduino Uno with USB-B Cable


When using lead, take precautions like:


  • Make sure to wash your hands with soap and water twice after you solder
  • Don’t eat the solder
  • Don’t touch your face or eyes after touching the solder
  • Wear a mask to prevent the solder smoke to come into your mouth, or to prevent you from inhaling it
  • When working with hot solder, you especially want to wear eye protection


Assembling the Kit:


Take out the ArduSensor Magnet PCB out of the the bag and put face up into a vice or third hand.  Bend the leads of the reed switch into an upside “U” shape.

Insert the reed switch into the copper holes corresponding with the “SOWAY” text facing up.  Make sure that you are putting it in the right way!

Flip the PCB over and put it back into the vice or third hand face down, so that all of the leads show on the back.  Bend the two leads outwards.

Put your soldering iron on one of the junctions where there is a copper hole, and one of the reed switch legs popping through it.

Wait three seconds, and then take your solder, touch it briefly to the junction, and then take your soldering iron away.  The junction should look something like this volcano shape:

Repeat this process once more to the other joint with the copper hole and a reed switch leg popping through it.

Trim the leads with your diagonal cutters, so that they don’t poke you.

After you are done, flip the PCB over again so that the text and reed switch are facing upwards.

Take your 10K (Brown, Black, Orange, Gold) ohm resistor out.

Bend the leads so that they make an upside-down “U” shape. 

Put these two leads into the 10K ohm resistor footprint on the PCB.  

Flip the PCB over and bend the leads of the resistor out in opposite directions.

Solder the two copper holes that have resistor legs popping out of them (using the same method as before).

Take the 1 pin male header and 4 pin male header, and put them into these Arduino pins:  The 1 pin male header goes into A0, and the 4 pin male header goes into VIN, GND, GND, and +5V as shown below in the picture.  

Place the ArduSensor Magnet on top of these pins, making sure that the 1 pin male header goes into the 1 pin male header socket, and the 4 pin male header goes into the 4 pin male header.

Solder in place.  But make sure that you don’t put too much solder in, because that can cause the ArduSensor Magnet to be permanently installed on your Arduino!

Wait for the ArduSensor Magnet to cool off (around 20-30 seconds), then pull out of the Arduino sockets.  Now you are finished soldering your ArduSensor Magnet!




If you haven’t downloaded the Arduino IDE, go here to download the latest version.  If you haven’t installed drivers for the Arduino (haven’t downloaded the software yet, or haven’t done this step yet), read the following table:


If you have...

Arduino Uno

Arduino Leonardo


No drivers needed, proceed to the next step

Go here, then proceed


Go here, then proceed

Go here, then proceed



Put your ArduSensor Magnet into your Arduino like this: Put the 1 pin male header into A0, and the 4 pin male header in VIN, GND, GND, and +5V.  



Plug in your Arduino with your USB cable (USB-B on the Arduino UNO or earlier, and USB-microB for Arduino Leonardo) to your computer.  Download this zip file and unzip onto your computer.  If you are on a Mac, double click the folder labeled “FishBank-ArduSensor-Magnet-Example-Code-f78ead3”, double-click the file named “MagnetRead.ino”, then press OK when the dialogue box pops up. If you are on a Windows computer, press Save instead of Open when you press the download button, double click the folder labeled “FishBank-ArduSensor-Magnet-Example-Code-f78ead3”, double-click the file named “MagnetRead.ino,” and then press OK in the pop up box.

The Arduino IDE should open up with the ArduSensor Magnet Read sketch.  This sketch prints out if there is a magnet nearby the reed switch.

First, make sure to select the board that you are using from Tools > Board.

Then, go into Tools > Serial Port, and select the correct COM/Serial Port.  On a Mac, the usual Serial Port will be /dev/tty.usbmodemfa131.  Any small variation of that will be fine.

On Windows, the COM Port will usually be COM 4, and anything lower or higher might work.

Here are the basic buttons/functions in the Arduino IDE:

Now let’s upload the sketch/code to the Arduino.  Plug one end of the cable into your Arduino, and then the other end into your computer.  Press the Compile + Upload button (Verify if there is any errors in the code, and then upload the sketch/code onto the Arduino), and the program will run on the Arduino.

Press the Serial Monitor button (in the upper-right hand corner), and you should see that it prints out either “Magnet Close!” or “Where’s the Magnet?”.

If you have any more questions on this product or how to use it, contact Qtechknow Tech Support at


Return To Tutorial List


Enter Security Code Below: