Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Homework Tasks

The 555 Fan

1 The PCB build


Learn It

  • In this project you're going to build a desktop-fan, whose speed can be controlled using a component called a potentiometer.
  • The circuit uses a 555 timer chip to control the fan.
  • You've had plenty of experience of soldering PCBs by now, so minimal guidance has been provided. However, putting together the actual fan takes time, so you are better off starting early.

Build It

  • Here is the board you will be soldering together.


  • First, you need to add the rectifier Diodes. Make sure you put them the correct way around, you can also add the 3 resistors.


  • Next add the 2 ceramic capacitors. Be careful, there are 2 values 10nF (103) and 100nF (104).
  • You can also add the TIP122 transistor. Make sure this is the correct way around.


  • You need to now cut 2 sets of red and black wires.
  • 130mm (13cm) for the motor.


  • 60mm (6cm) for the switch.


  • These can now be soldered to the motor and the switch. Please note how the wires are soldered in a particular direction on the motor.

7_Motor_wires_added.JPG6_Switch wires_added.JPG

  • The wires for the motor can now be fed through the housing and then soldered to the PCB.
  • Make sure they go through the strain relief hole.


  • You can now solder the switch to the PCB.
  • Again, make sure you use the strain relief hole.


  • Finally, add the Potentiometer to the PCB and it is now ready to go into the housing.


Badge It

  • Take photos of the solder and component side of your board, and the leads to your switch. Your badge will be awarded according to the quality of your work.
  • Now it is time to test your board.