DIY Micro:bit Aromatherapy Pomodoro Timer | Build Your Scented Productivity Tool

You know Pomodoro timers: 20-25 minutes of focus time followed by short breaks. Here, at the end of your focus period, a small USB fan turns on, spreading a pleasant aroma from the essential oil you’ve dropped into it. No bells or alarms—just an LED effect and a cool aromatic breeze. It’s easy to build and makes your home office desk “smart.”

---

Required Materials

Component	Specification / Quantity
Micro:bit (V1 or V2)	–
5V USB mini fan	40-60 mm diameter, < 200 mA
Power supply	Powerbank or USB adapter
NPN transistor (2N2222)	For driving the fan
Diode (1N4148)	For back emf
100 Ω resistor	Transistor base resistor
Crocodile cables × 3	For easy connections
Cotton pad + essential oil	Lavender / mint (1 ml)

Alternative: If you find an ultra-mini 3V fan instead of 5V, you can power it directly from the Micro:bit batteries without a transistor (≤ 90 mA). The USB fan definitely works and is brighter, which is why we used it in this example.

---

Step-by-Step Setup (Total ≈ 45 min)

1. Set Up the Circuit (10 min)

Micro:bit P0 ──■──────┐
               │  100 Ω
               ▼
           Transistor (2N2222)
               ▲
Fan GND  ──────┘──▶│ 1N4148
Fan +5 V ─────────────(+5 V USB)
Micro:bit GND ────────────────┘

• The 100 Ω resistor limits the current from P0 and protects the transistor.
• The 1N4148 diode “quenches” voltage spikes generated when the fan coil turns off.

2. Prepare the Scented Pad (3 min)

Drop 1-2 drops of essential oil onto the cotton pad, attach it to the center of the fan with double-sided tape.

3. Upload the Code (15 min)

In MakeCode, click “New Project” → paste the following in the JavaScript tab:

let workTime = 20 * 60 // seconds
let fanTime = 30       // seconds
let counter = 0

input.onGesture(Gesture.Shake, function () {
    counter = 0
    basic.showIcon(IconNames.Heart)
})

basic.forever(function () {
    basic.pause(1000)
    counter++
    // LED countdown graph
    let bar = Math.map(counter, 0, workTime, 25, 0)
    led.plotBarGraph(bar, 25)

    if (counter >= workTime) {
        // Run the fan
        pins.digitalWritePin(DigitalPin.P0, 1)
        for (let i = 0; i < fanTime; i++) {
            basic.showRainbow()
            basic.pause(1000)
        }
        pins.digitalWritePin(DigitalPin.P0, 0)
        basic.clearScreen()
        counter = 0          // New focus cycle
    }
})

How it works:

1. Shake → resets the counter, starts a new focus period.
2. Every second, the countdown column in the LED matrix decreases.
3. When 20 min (1200 sec) is up, P0 goes HIGH → fan runs for 30 sec, LEDs flow in rainbow animation.
4. Fan turns off, cycle starts again.

4. Make a Case/Stand (10 min)

• Secure the fan to a small angled cardboard base facing the desk; keep the cotton pad at the front.
• Attach the Micro:bit to the powerbank with double-sided tape; shorten cables and tidy up the desk.

5. Test It (5 min)

1. Turn on the powerbank, start with “shake” in a closed room.
2. After 20 minutes, observe the fan activating, the aroma spreading, and the LED animation finishing.
3. If the fan doesn’t turn, check the connections and the USB 5V power supply.

---

How It Works

Component	Function	Detail
Micro:bit	Timer + LED animation control	Counts seconds with counter variable.
Transistor	Converts P0 signal to switch for 5V fan	2N2222 NPN, comfortable up to 200 mA.
Diode	Absorbs inductive voltage	Fan coil generates reverse voltage when turning off.
Cotton + essential oil	Aromatic vapor	Fan carries scent from pad through breeze.

---

Development Ideas

Improvement	Benefit
Add OLED display (I2C)	Show remaining time in minutes-seconds.
Three-mode timer	A button: 15 min work / B: 25 min / shake: reset.
RGB NeoPixel ring	Colorful light effect during breaks.
Humidification version	Add ultrasonic “mist” module to create aroma vapor.

---

Frequently Asked Questions

Question	Answer
Battery instead of USB?	You can get 5V with 2×AA NiMH + boost module; powerbank is more practical.
How many drops of essential oil?	1-2 drops of lavender provides a cool, soft scent; mint is refreshing.
Why P0 HIGH/LOW?	For transistor base current; P0 HIGH → base current flows → fan on; LOW → off.
Advantage of Micro:bit V2?	V2 has a sound chip but it’s not necessary for this project; both work.

---

Conclusion & Share

Now you have an aromatherapy timer that reinforces the work-break cycle with scent, minimal wiring, and adds elegance to your desk. Share your photo on social media with the hashtag #ScentedBreaks, and experiment to find which oil blend keeps you more energized!

Wishing you fragrant breaks!