I am trying to make a hotplate with an ESP32 and I use MC34063 for buck/boost converters. The hotplate itself require 12-30V to operate and the ESP32 and LEDs need 3.3V. 

Here is the circuit:

[![DC-DC Converter Circuit][1]][1]

When the circuit is powered, I hear (almost) nothing while the ESP32 is booting but after that, I can hear an annoying audible noise. I tested with an oscilloscope and the output of the MC34063 seemed to have a frequency between 10 and 15kHz.

I have already checked [this question][2] but it does not seem to have a complete solution for my case.

You can find the complete schematic [here][3] and the PCB [here][4]


  [1]: https://i.sstatic.net/cScFo.png
  [2]: https://electronics.stackexchange.com/questions/475084/mc34063-based-converter-accoustic-noise
  [3]: https://oshwlab.com/loicdaigle31/hot-plate
  [4]: https://easyeda.com/editor#id=c7828c61b3fe474da5bdae3b2b77eb8f