Mykola Dmytroych Pylchykov (Ukrainian : Микола Дмитрович Пильчиков, 21 May 1857, Kharkiv, Russian Empire (present-day Kharkiv, Ukraine) – 19 May 1908, Kharkiv, Russian Empire) was a physicist, inventor, and geologist in the Russian Empire. He is known for the discovery of the photovoltaic effect, new properties of X-rays, and ways to control various mechanisms of the radio provided a basis of radio control.