Introduction: Smart Lock USB. Use Magnet Polarity to Unlock and Lock Usb.

About: Gardener, poet, anything aha!

So many type of usb, and so many uses of usb. Fan, lights, air conditioner, hand warmer, drill, and many tools now is using this small usb!. Now, i will make something special from usb.

Everyday i use usb plug from my pc, but the usb plug is to far from me, so i make this usb extension. But i don't want other people use my extension, so i make this usb extension with special feature! I can lock and unlock my usb extension with magnet.

If this usb is locked, the power from input usb will closed, so the usb can't works. Also you can modification your PowerBank with this trick, so only you can use it and know how to use it.

Ok, Lets make it!

Step 1: Materials and Tools

Ok, in this project, you just need 5 material for make this. All of the materials is cheap and you can easily to buy it.

The materials is:

  1. PC Fan
  2. Magnet
  3. USB (Male and Female)
  4. Cables
  5. Electrical tape
  6. Case (Optional. In this case, i use keyboard button)


  1. Soldering iron
  2. Scissors, knife

Step 2: PC Fan

First, open and take out fan blade. Its easy to take out the fan blade, you just need to open the seal on back of the fan and pull out the blade.

After that, slowly pull out the pcb. We just need the polarity sensor. It looks like image 5!

Next, unsolder the polarity sensor from fan pcb.

Step 3: Polarity Sensor

After unsolder the polarity sensor, now solder wires to the legs of the polarity sensor. For the polarity you need to choose one, north/south. The legs output and input is like image 2.

1 Input Positive

2 Output negative south

3 Output negative north

4 Input negative

Step 4: USB

Now, take your cables and strip all the wire. Solder all the wire to usb male. The pinout of usb looks like image 2. Next, Solder another end of cables to usb female. Solder all wire except the Input -(Gnd) wire.

After that, solder the wire from polarity sensor to usb female. The circuit is like image 6.

Step 5: Make the Usb Nice Look

First, i close the circuit with electrical tape, next i insert the usb female and the sensor inside my case, glue the case, and i make it more nice look with electrical tape.

Step 6: Make the Key

For make the key, i used 1 medium magnet and metal ring. Glue the magnet to the metal ring, wait until dry, next decorate your key.

Finish, final step is reached.

This usb feature is really cool. You can prank your friend with this usb extension. Nobody can use this usb except you / have the key. Also, this is a great project for enter a contest . Like school science contest, or even another big contest!.

Step 7: Test

All finish!, If you like this project please share, like or vote me :). If you have any question or problem please comment under this steps!

Thank you and have fun with your projects!

Explore Science Contest 2017

Participated in the
Explore Science Contest 2017

Invention Challenge 2017

Participated in the
Invention Challenge 2017