# Hendrik van der Bijl

Hendrik Johannes van der Bijl (born November 23, 1887 in Pretoria , † December 2, 1948 in Johannesburg ) was a scientist and entrepreneur from South Africa .

He obtained his doctorate in physics in Leipzig . After working as a physics lecturer in Dresden in 1912, he became a scientist at AT&T in the USA. During the First World War he developed the first American miniature electron tube VT-3. The civilian successor was produced as the 215A by Western Electric since 1919 .

General Smuts brought van der Bijl back to the Union of South Africa as technical advisor to the government . He became chairman of Eskom , Iscor and the South African Industrial Development Corporation . From 1934 to 1948 he was Chancellor of the University of Pretoria . In 1943 he was elected to the National Academy of Sciences . The industrial town of Vanderbijlpark , a site for iron and steel processing south of Johannesburg , was named after him.

The equation for triode electron tubes comes from van der Bijl . S is the slope, D is the penetration and R i is the internal resistance of the triode. In Germany this formula is known as Barkhausen's tubular formula . ${\ displaystyle S \ cdot D \ cdot R_ {i} = 1}$

## Individual evidence

1. ^ Gerald FL Tyne: Saga of the Vacuum Tube. Prompt Publications, 1977, Chapter 14, pp. 292ff.
2. Hendrik Johannes Van der Bijl: The thermionic vacuum tube and its applications . McGraw-Hill, 1920.