ESP humidifier

I. Humidifier Design
  The humidifier uses an NE555 timer to generate a 108kHz square wave to drive the spray nozzles. Direct drive voltage is too low, so a boost circuit is used to increase the voltage. An ESP-12S control chip is added to enable IoT control of the humidifier. An AHT20 temperature and humidity sensor is used to detect ambient temperature and humidity.
II. Boost Circuit The
  boost circuit consists of two parts:

a 12V boost circuit
  and a MT3608 boost chip. The 12V boost circuit ensures the minimum operating voltage for the spray nozzles.

The output voltage depends on the ratio of two resistors, calculated according to the formula in the chip's datasheet. These two resistors were adjusted based on my existing resistors.

The boost circuit
  is shown in the diagram below. The switching transistor controls the inductor's energy storage and release, resulting in a higher output voltage than the input voltage.

III. Frequency Generation Circuit A
  555 timer is used to generate a 108kHz frequency. The output frequency calculation is shown in the diagram. Since I used existing components, and considering the accuracy of the capacitors, the actual output frequency needs to be tested to ensure it matches correctly.
IV. Non-contact Liquid Detection:
  The TC301D is used for non-contact liquid detection. Pay attention to the PCB layout; specific details can be found in the datasheet.
V. Shortcomings and Optimizations:
  Because many components are readily available, the circuit power supply is insufficient. The inductors and capacitors in the boost circuit could be replaced with smaller ones. Non-contact liquid detection has not yet been verified.