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The Smart Charizard Diffuser is a 2021 Engineering Dads hobby project that puts an Arduino Uno, ESP8266 Wi‑Fi module, ultrasonic atomizer, humidity sensor, pump and LEDs inside a Charizard-themed enclosure. It can mist automatically when its DHT11 reports low humidity, accept manual commands from a button or Blynk, and pump liquid from a separate reservoir. It is a maker prototype—not a certified humidifier, medical device or unattended, production-safe appliance.
The original build is useful as an educational starting point, but its documentation has important gaps: the pump-switch component is described three different ways, the public sketch contains credentials, the fill system relies only on a timer, and the single 80% threshold can chatter. Treat the project page and historical sketch as references to redesign and test, not as a copy-and-upload recipe.
What the Smart Charizard Diffuser actually is
Engineering Dads published the project on August 14, 2021, on Hackster.io. The Pokémon theme comes from the custom enclosure and lighting; underneath is a conventional microcontroller-controlled ultrasonic mist system.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →- Misting: A Grove ultrasonic atomizer turns liquid into mist. The project description says its driver operates at about 105 kHz; verify the exact module before treating that as a universal specification.
- Humidity feedback: A DHT11 measures temperature and relative humidity. Its reading is local to the sensor, especially if it is placed near the mist outlet, and does not prove that the whole room is at the target humidity.
- Automatic filling: A 6 V peristaltic pump moves liquid from a separate container through vinyl tubing into the diffuser.
- Remote control: An ESP8266-01 provides Wi‑Fi connectivity to Blynk through the Arduino.
The project page labels the work “Advanced” and displays a GPL3+ license label. Confirm the applicable license terms before redistributing modified code or enclosure assets.
#1 Best Overall
- EASY EVERYDAY AROMATHERAPY: The AuraDrop Fan Diffuser keeps aromatherapy simple and mess-free with no water or heat required. Just add a few drops of essential oil to the reusable fiber pad, turn it on, and enjoy gentle scenting powered by a quiet built-in fan.
- GENTLE FAN-POWERED DIFFUSION: A small internal fan softly moves essential oil aroma into the air without mist, steam, or residue. This dry diffusion style is ideal for desks, bedrooms, shared spaces, and cozy corners where you want fragrance without humidity.
- FUN COLOR CHANGING LIGHT FEATURE: Built-in color-changing lights add a playful pop of color to your space. Choose between rotating shades or keep it set on your favorite color to match your mood, décor, or time of day.
- PORTABLE FOR HOME OR TRAVEL: Compact and lightweight, the AuraDrop runs on two AAA batteries (not included) or the included USB cable. Comes with three fiber pads so switching scents is quick and easy, making it perfect for home, office, or travel use.
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Original hardware and software
Bill of materials
| Part | Role or qualification |
|---|---|
| Arduino Uno R3 | Main controller |
| DHT11, four-pin version | Temperature and humidity input |
| Grove water atomizer and driver | Ultrasonic mist generation |
| 6 V Grothen peristaltic pump | Liquid transfer from the reservoir |
| ESP8266-01 | Wi‑Fi and Blynk connection |
| LM2596 buck converter | Steps the pump supply down to approximately 6 V |
| Switching device | Documentation conflicts: NPN TIP120, n-type MOSFET, and an “IGBT Single Transistor, 120 A” appear in different sections |
| 1N4001 diode | Flyback protection across the pump |
| Resistors | Two 330 Ω, two 1 kΩ, approximately 2 kΩ, and 10 kΩ values are listed |
| Two LEDs and piezoelectric transducer | Status/Charizard-eye indication and sound |
| Power supply, jumper wires, vinyl tubing, cotton wick, reservoir | Power, liquid path and atomizer consumables |
| Custom 3D-printed enclosure | Project housing; visible text does not specify dimensions, wall thickness, filament or tolerances |
An Anycubic 4Max Pro 2.0 is named among the tools, but the page does not publish reproducible print settings or complete enclosure files in its visible text.
Pin map and timing values in the sketch
| Function | Sketch detail |
|---|---|
| DHT11 data | Arduino digital pin 2 |
| Atomizer control | Pin 3 |
| Pump control | Pin 11 |
| Left and right LEDs | Pins 8 and 6 |
| Physical mist button | Pin 7 using INPUT_PULLUP |
| ESP8266 SoftwareSerial | Arduino pins 9 and 10 |
| ESP8266 serial speed | 112,500 baud |
| USB serial monitor | 115,200 baud |
| Pump cutoff | 35,000 ms (35 seconds) |
| Button debounce | 20 ms |
| Blynk sensor update | Every 1 second |
| Blynk connection check | Every 5 seconds |
| Blynk virtual pins | V2 diffuser, V3 pump, V4 mode, V5 humidity, V6 temperature |
These values come from Smart_Diffuser.ino; software behavior may require changes for current Arduino and Blynk libraries.
How the electrical architecture is intended to work
The described arrangement uses a 12 V supply for the pump path and an LM2596 buck converter to provide approximately 6 V to the pump. The pump is switched on the low side by a transistor or MOSFET, with a 1N4001 across the inductive load. The Arduino reads the DHT11 and drives the atomizer, pump, LEDs and buzzer. The ESP8266 communicates over a serial link and connects the device to Blynk.
Do not substitute the three switch descriptions casually. A TIP120 is an NPN Darlington transistor, a MOSFET has different gate and conduction requirements, and an IGBT is another device category. Before energizing the circuit, identify the exact part, check its pinout and ratings, verify whether the Arduino drive is suitable, and size the diode, wiring and heat dissipation for the measured pump current. The original page does not resolve this contradiction or provide a reliable pin-by-pin wiring table.
Automatic humidity mode
When Blynk’s mode control selects automatic operation, the sketch compares the DHT11 reading with approximately 80% relative humidity:
- Above 80%: the atomizer and both LEDs are switched off.
- Below 80%: the atomizer and both LEDs are switched on.
- Exactly 80%: neither comparison explicitly handles the value.
This is a single-threshold controller, not dependable room-humidity regulation. Sensor noise around 80% can repeatedly switch the atomizer. A safer redesign should use separate on and off thresholds plus minimum on/off times, with values selected and tested for the intended room. Place the sensor away from the mist plume and check readings for plausibility; the code mainly rejects NaN and does not calibrate the DHT11.
Manual button, Blynk controls and filling
Manual operation
The physical button on pin 7 uses the Uno’s internal pull-up. The intended first press turns on the atomizer and LEDs; the second turns them off and resets the counter. Blynk V2 provides diffuser on/off, V3 provides pump control, and V4 selects manual or automatic mode. The comments and conditionals are awkward, so test the actual state transitions rather than assuming the interface is polished.
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Rank #2
- Now With Dual Power Options – Use 4 AA batteries for cordless convenience or plug into USB for extended run time at your desk or bedside.
- Improved 30-Day Fragrance System – Upgraded gravity-fed bottle design ensures up to 30 days of clean, continuous dry scent delivery.
- Now Compatible with EVA Inserts – Perfectly fits 10 ml essential oil bottles and the new long-lasting, mess-free EVA fragrance pads. Please note that larger bottles will not fit, ensuring a snug, secure fit every time.
- Zero-Mist Technology – Dry fan diffusion means no spills, no water, and no risk of moisture damage near electronics.
- Compact, Quiet & Travel-Ready – Whisper-soft fan, sleek modern design, and mess-free operation make it perfect for personal spaces and on-the-go use.
Reservoir and pump cycle
The creator describes a separate sugar-container reservoir with a drilled outlet, vinyl tubing secured with an adapter and hot glue, and cotton wicks soaked in the liquid mixture. The pump is stopped after about 35 seconds; flashing Charizard-eye LEDs indicate that the timed fill cycle has reached its limit.
Thirty-five seconds is a software cutoff, not a liquid-level measurement. Flow changes with pump wear, tubing resistance, reservoir height, air in the line, wick condition and supply voltage. It cannot by itself prove that the diffuser is full or prevent overflow. Add a physical overflow route and, preferably, a float, optical, capacitive or load-cell level sensor. Never leave a timed pump running unattended over electronics.
Security, liquid and maintenance problems to fix
Credentials
The public sketch contains fields that appear to hold a Wi‑Fi network password and Blynk authentication token. Treat them as compromised. Do not copy them, publish replacements, or reuse the historical token. Create a new Blynk template/device and store fresh credentials outside any public repository; redact them from screenshots.
Electrical and moisture safety
- Keep the reservoir, tubing and atomizer in a sealed liquid path physically separated from electronics.
- Use drip loops, strain relief, a moisture-resistant nonflammable enclosure and an independent spill/overflow strategy.
- Use a suitable fuse or current-limited supply and keep all mains wiring enclosed; test with low-voltage power before final assembly.
- Check ESP8266 3.3 V supply capacity and Arduino-to-ESP8266 logic-level compatibility.
- Inspect the diode polarity, grounds, connectors and buck-converter output under pump load.
The original page discusses avoiding leaks but does not establish a complete electrical-safety design. Essential oils also require compatibility checks for the reservoir, tubing, adhesives, cotton, pump and printed plastics. Do not imply that any mixture is safe for every person, pet, respiratory condition or ultrasonic component.
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Cleaning
Water-based mist systems can grow contamination when left wet. Establish a routine to empty, rinse and dry the reservoir and tubing, replace or clean the wick as appropriate for its material, and use only cleaning agents compatible with the atomizer and plastics. The project record does not specify a validated cleaning schedule or antimicrobial treatment.
A safer reproduction sequence
- Download the repository and inspect the sketch; remove every credential before saving or sharing it.
- Install the DHT, ESP8266 and Blynk libraries appropriate to the current board environment, and use SoftwareSerial only if required. The 2021 page does not verify modern library versions or provide a current Blynk setup walkthrough.
- Identify the actual pump switch and verify its pinout, ratings and drive requirements. Do not build from the conflicting TIP120/MOSFET/IGBT descriptions.
- Test the DHT11 alone and confirm stable readings on the serial monitor.
- Test LEDs, buzzer and atomizer without liquid; confirm the atomizer driver and transducer are the intended pair.
- Power the pump through the buck converter from a current-limited supply. Install the flyback diode across the pump with the correct polarity and measure voltage under load.
- Prime the tubing, check fittings and run a leak test outside the enclosure. Keep liquid away from the Uno, ESP8266 and power connections.
- Measure delivered volume during a 35-second run. Use that measurement only as a starting calibration; replace the timer with level sensing and an independent overflow path where possible.
- Only after local controls work, connect the ESP8266 and configure a fresh Blynk device. Treat 112,500 baud as a project-specific setting and change it if the module or library requires another speed.
- Run supervised tests with the finished enclosure, checking temperature, resets, leaks, overflow and sensor placement before considering longer operation.
Troubleshooting
ESP8266 does not connect
- Regenerate Wi‑Fi and Blynk credentials; never use values exposed in the old sketch.
- Check crossed TX/RX wiring, common ground, 3.3 V current capacity and logic levels.
- Try the project’s 112,500-baud setting, but confirm the module’s actual configuration.
- Allow for changes in Blynk APIs and libraries since 2021.
Pump runs but liquid does not move
Check polarity, buck output under load, tubing diameter, reservoir height, trapped air, priming, wick blockage, transistor saturation, heat and diode orientation.
Pump overfills
The timer is the only documented cutoff. Measure flow, shorten supervised test cycles and add a float/optical/capacitive sensor or mechanically limited reservoir. Do not call the 35-second value an overflow sensor.
Rank #3
- WATERLESS - Convenient operation! No need to add the water, simply remove cover and drop one or two drops of the oil or fragrance to the pad. Secure cover, turn on and it begins to diffuse.
- OPERATED BY RE-CHARGABLE BATTERY OR USB - Runs using an included USB cable or option for re-chargeable battery. Level 1 speed run time approximately 5.5 hours, Level 2 run time approximately 2.5 hours and Level 3 run time approximately 1.5 hours.
- QUIET – Operation at the standard Level 1 diffuser runs quietly.
- DIFFUSER – Diffuses essential oils very effectively. Only a few drops required depending on scent, turn on and begin enjoying the smell immediately!
- QUALITY - Made of high-quality material including medical grade material pp. BPA-free and essential oil friendly materials.ABSORBING PADS – Included with diffuser are eight (8) replaceable micro-absorbing pads.the pads
No mist
Confirm the driver/transducer pairing, supply voltage, liquid contact, wick condition and cleanliness. Avoid dry operation. Verify the module’s specified frequency instead of assuming the page’s approximately 105 kHz claim applies universally.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsOscillation, resets or random behavior
Use hysteresis and minimum run times for humidity control. For resets, investigate pump spikes, shared supplies, grounding, atomizer noise, long jumper wires, missing decoupling and ESP8266 current demand.
Who should build it—and who should choose something else
It suits experienced Arduino makers, educational demonstrations, themed 3D-printing projects and builders willing to redesign the wiring and software around a contained liquid system. It is a poor fit for beginners seeking a copy-and-upload project, unattended bedroom or nursery use, certified humidification, precise room control, or secure remote access without modernizing the software.
A practical redesign would use one ESP32 instead of the Uno-plus-ESP-01 pair, local control instead of cloud credentials, and a physical level sensor rather than a timer. If the goal is simply scheduled mist and themed lighting, a commercial diffuser with appropriate safeguards and a smart plug is less complex. These alternatives reduce failure modes but no longer reproduce the original architecture.
Source links and project status
Read the original project record at Hackster.io, the source repository and its sketch. The project also links to a demonstration video at YouTube. Hardware references surfaced by the page include the Arduino Uno Rev3, an Adafruit DHT11 listing and Blynk; availability, pricing and compatibility must be checked for the buyer’s region and date.
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Verdict: The Smart Charizard Diffuser is an inventive IoT and fabrication exercise, but the historical instructions are not sufficient for a safe, reliable reproduction. Build it only after resolving the switching-device contradiction, rotating all credentials, adding real level/overflow protection, modernizing the control software and separating liquid from electronics.
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