I modified a fan to make it controllable with a remote. It allows you to use the fan at different speed settings.
At the first three presses of the remote, the fan changes speed from low to high. The next three presses change the speed again from low to high but also enable the outer rim. The next press turns the fan off. At every state change, a buzzer that I included plays a sound.
The fan has 3 different speed settings as a rotary multi-switch on the front panel. It also has a switch that enables an outer rim that spreads the air flow. I kept those to allow you to use the fan manually if for some reason you want to.
I used parts from a “remote controlled bell”. By remote controlled bell I mean a device that when you press a button on a remote, a bell up to a few meters away makes a sound. I took out the main board and found which contact goes HIGH on button press. After that the process was pretty straighforward. I used an AVR microcontroller with the receiver as input and a couple of relays as output. I didn’t have to alter the remote control in any way. To power the circuit, I used an old phone charger followed by a voltage regulator.
Example usage below: