Every component was chosen against noise.
A fan's electronics boil down to four functions: power, drive, regulate, command. For each one, the sizing work looked for the off-the-shelf component that serves silence — a filtered 12 V supply that does not whistle, an outrunner brushless motor whose propeller mounts straight on the rotor, an FOC driver with sinusoidal currents, an ESP32-S3 that brings wireless for free.
The whole thing fits in a bill of materials of about $40, hand-soldered on the prototype — an all-in-one board will eventually gather driver, converter and connectors. Standard components are not a compromise: they are what makes the product repairable, upgradable and fast to industrialize.
Learn more — click a sub-step
01The architecture
From wall to motor, the chain is short and readable: a filtered 12 V switching supply, a power switch, a filtering stage — ferrite ring and 100 µF + 100 nF decoupling capacitors — then the driver feeding the motor in three phases.
In parallel, an LM2596 buck converter steps the 12 V down to 5 V for the ESP32-S3 control board, which reads the potentiometer, talks Bluetooth Low Energy with the mobile app and sends its command to the driver. Every link has an acoustic justification — none is there out of habit.
02The 5010 motor
The outrunner format — outer rotor, fixed stator — is a fan's natural geometry: the propeller bolts straight onto the rotating bell, no gearbox, no coupling, hence no gears to whine. The 5010-14 in its 360KV winding tops out around 4,320 rpm under 12 V: exactly the useful range, with enough torque to start without jolts.
The non-negotiable condition for silence: pre-lubricated ball bearings. The rest is a matter of cost — $16 apiece — and availability: it is an RC-hobby standard, mass-produced, replaceable in two minutes.
03FOC drive
A standard drone ESC drives the motor with trapezoidal commutation: at every switch, the current jumps from one phase to the next and the winding takes a jolt — the telltale buzz of multirotors. The Ventilencieux uses Field Oriented Control instead: the SimpleFOC Mini driver injects sinusoidal currents into the three phases.
Torque becomes continuous, discontinuities vanish, and the switching frequency settles beyond the threshold of hearing. At low speed — where a silent desk fan lives — the difference is immediately audible.
04The brain: ESP32-S3
The control board is an ESP32-S3: analog reading of the 10 kΩ potentiometer, high-frequency PWM to the driver, and above all native Wi-Fi and Bluetooth Low Energy — the mobile app's connectivity (step 07) costs no extra component. Programmed in MicroPython, it lets the firmware iterate in seconds.
On the prototype, everything is hand-soldered and each component is measured with calipers to fit into the CAD to the millimeter. And the next move is already drawn: a dedicated board, presented below.
05The all-in-one board (KiCad)
The hand-soldered prototype already has its successor: a board designed in KiCad, round to nest into the base, gathering the ESP32-S3, the filtered potentiometer input, the command output to the driver and the power decoupling — with a copper-free zone reserved under the antenna so Wi-Fi and Bluetooth are never smothered.
The schematic deliberately fits on one page: an RC filter on the potentiometer reading, a series resistor and a pull-down on the command line, bulk and decoupling capacitors on the 5 V rail. Enough to replace hand wiring with a board assembled in minutes.