How to Build an Electronic Fan Controller

Build the Prototyping Environment

• 1

  Open your PICAXE-08M proto board kit and place the parts in position. Insert the two resistors, capacitor and DIL socket. Bend the pins out slightly on the reverse of the board to prevent them from dropping out.

• 2

  Check the polarity of the components and solder them in place.

• 3

  Connect the L293D driver IC to the PICAXE 08M chip via the proto board. Connect pins 4, 5 and 13 via a heat sink to ground. Use the thin gauge wire to make these connections.

• 4

  Connect the remaining driver input pins to the PICAXE controller according to the datasheet. Connect the fan motor to pins 3 and 6 of the L293D chip.

• 5

  Solder in place the 1N4001 reverse bias diode across the terminals of the fan to prevent back EMF from damaging the circuit.

Upload the Code to Your PICAXE Chip

• 6

  Connect your PICAXE proto board to your computer using the data cable.

• 7

  Input the PWM commands into the PICAXE interface. The syntax for this is "pwm pin, duty, cycle". So for the fan controller system used here, the command would be "pwm 2, variable1, variable2". You can find further usage of the PWM function in the PICAXE manual.

• 8

  Connect the power supply and upload the code to your PICAXE chip.

• 9

  Remove the data cable, reset the power supply and test your electric fan controller.