Simple Automatic Bathroom Fan




Introduction: Simple Automatic Bathroom Fan

Welcome Back!

I have in this project made a moist sensor that activates the bathroom fan if the moisture get's to high. (>50%)
The problem was that the fan was always on if the bathroom lights were turned on. I could have installed a new fan with moist sensor instead but i didn't want to pay for one and I had all the parts laying around.

Here we go!

Step 1: Parts You Will Need

All the part's needed for this projects depends on your fan.

Some Fans are 12V DC and others are 220/110V AC.

Mine was 220V AC.


Wireing box/project box

Arduino Pro Mini:



AC-DC Converter:


Step 2: Soldering

Now it's just a bit of soldering.

Following the schematic should be fairly easy.

Step 3: Programming

Using the code in this step will give you a line that is set to 50% humidity. if you live in an area where this normal you can just pump up that number :-)

Our normal humidity is approx. 20%

And this is where you will need the FT232 to upload your code to the Arduino.

Step 4: Done!

Now that your have finished soldering and uploading the code, it should work!

Try testing it by breathing on to the moist sensor to see if the relay switches.

Last thing to do is to wrap it up in the box. but make sure the moist sensor is sticking out! and place it as high as possible. This is where the moisture will be when you are taking a shower or pouring boiling water on to your floor... don't ask me why you would to something like this.

If you liked the project feel free to hit subscribe to see more practical and not practical projects!
and then there is the vote button.. I wont force you.. but if you don't.. who knows what might happen?

Microcontroller Contest

Participated in the
Microcontroller Contest

Be the First to Share


    • Mason Jar Speed Challenge

      Mason Jar Speed Challenge
    • Pumpkin Challenge

      Pumpkin Challenge
    • Bikes Challenge

      Bikes Challenge

    3 Discussions


    Question 2 years ago

    Is there some sort of manual timed override? I'm thinking that as much as a fan removes moisture, it also removes odour.


    Answer 2 years ago

    If codeing is not your strong side i could help you make the addition?


    Answer 2 years ago

    It would be a great idea to add a button on the side or somewhere easy to reach.
    I would make the button activate a timer that counts for each cycle and then when the counter, reaches 1 minute or something it would reset and turn of the fan :-)

    Great idea!