Instructions

PROJECT 5. FAN SPEED CONTROLLER
You will need:
• micro:bit
• MonkMakes Relay for micro:bit
• AA Battery holder and battery
• Motor with fan attached
• Program: P5 Fan Speed
In this project you will use the motor again,
but this time as a motor rather than a
generator.
Flash the program P5 Fan Speed onto your
micro:bit from the web address below:
https://makecode.microbit.org/_UeML9o6bTWhV
Connect up the components as shown to the right. Note it doesn't really matter
which way around the motor leads are connected. Reverse them and the motor
direction will reverse.
The micro:bit display will show a number between 0 and 9 indicating the fan's
speed. Use button B (on the micro:bit) to increase the speed and button A to
decrease the speed.
How it Works
This project uses the MonkMakes Relay to provide pulses of power of varying
length to the motor using PWM (see Project 3).
The code is the most complicated so far. It uses quite a few variables that are
defined in the on start block.
• min_power – This should be set to the minimum power output value that
makes the motor just start to turn. This varies a bit between motors. Try
the default value of 600, but if the motor doesn't turn when you press
button B to set the speed to 1, you may need to increase this value to
perhaps 700 or more.
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