Bernard D.H Tellegen. Photo by Unknown. Wikimedia Commons

Top 10 Intriguing Facts about Bernard D. H. Tellegen


 

Bernard D.H. Tellegen was a Dutch electrical engineer and inventor who was born on 24 June 1900 and died on 30 August 1990.

His invention of the pentode vacuum tube and the gyrator were the most memorable and notable of his many achievements throughout his career.

He is known for one of the most powerful theorems in network theory which was named Tellegen’s theorem, which is essentially a theorem in circuit theory.

Tellegen joined the Philips NatuurkundigLaboratoriumor or Philips Physics Laboratory in English in Eindhoven after obtaining a master’s degree in electrical engineering from Delft University in 1923.

The following are the top 10 intriguing facts about Bernard D. H. Tellegen.

1. Bernard D.H. Tellegen Invented the Pentode Vacuum Tube

Gilles Holst. Photo by Anonymous. Wikimedia Commons

Tellegen invented the pentode vacuum tube together with Gilles Holst in 1926.

A pentode vacuum tube also known as pentode valve has a total of five active elements within the envelope, having a further grid which is referred to as a screen grid.

 Many amplifier applications are known to use the pentode vacuum tube as it offers a high level of grain which overcomes the “kink” in the response curve of the tetrode valve in an amplifier.

The high levels of performance needed in many circuits can be achieved with a pentode vacuum tube.

2. Tellegen Invented the Gyrator In 1948

Gyrator-Capacitor Model. Photo by Constant314. Wikimedia Commons

In 1948, Tellegen invented the gyrator which is a passive, linear, lossless, two-port electrical network element.

After the resistor, capacitor, inductor and ideal transformer, a gyrator is the hypothetical fifth linear element.

Gyrators permit network realizations of two-(or-more)-port devices which cannot be realized with just the conventional four elements namely the resistor, capacitor, inductor and the ideal transformer.

The gyrator is non-reciprocal, unlike the four conventional elements and it makes network realizations possible.  

The gyrator is used in hi-fi graphic equalizers as without a coil it is useful to simulate the effect of an inductor without it.

3. Tellegen Was A member of Philips Research Laboratories Board of Directors

Philips Research Laboratories, Eindhoven. Photo by Rosemoon. Wikimedia Commons

Tellegen entered into the service of Philips Research Laboratories in Eindhoven in 1924 after obtaining his degree in electrical engineering from Delft University in 1923.

Holst and Oosterhuis had founded these laboratories in 1914 and Bernard belonged to a fairly small nucleus within the laboratories.

One of the largest research centers in the world grew out of that nucleus.

 Tellegen became a scientific adviser in the company and later became a member of the board of directors of the organization.

4. Tellegen Held About 57 Patents

Pentode Vacuum Tube. Photo by Joe Haupt from USA. Wikimedia Commons

Tellegen first studied the area of vacuum tubes but later became interested in electron motions in multigrid tubes and in triodes. 

His inventions were patented in several countries throughout the world.

 One such invention was the pentode vacuum tube in 1926 and which he patented. Either alone or in corporation with others, Tellegen held a series of about 57 patents.

In 1928, 1933 and 1934, Tellegen became interested in electrical circuits on which he published extensively.

5. Tellegen Showed the Impact of a Powerful radio Transmitter in Luxemburg

Beromünster LU. Photo by Jag9889. Wikimedia Commons

In 1932 it was realized that, the programs of some transmitters from Beromünster, Switzerland seemed to carry also the program of Radio Luxemburg when received in the Netherlands.

Cross-modulation was also suspected in the receiver tubes.  Tellegen showed that a powerful transmitter in Luxemburg caused a nonlinear effect in the ionosphere.

6. Tellegen Formulated the Tellegen Theorem

Tellegen published an important paper on a general network theorem with applications in 1952.

The simple relationships between magnitudes that satisfy Kirchhoff’s laws were given in Tellegen’s theorem.

Several treatises and a book were published on the application of Tellegen’s theorem. A feature of this theorem is that it applies to any system which can be represented by a directed linear graph.

7. Tellegen Inspired the major annual symposium of The Circuits and Systems Society

Between 6 to10th September 1971, Tellegen attended an International Symposium on Electrical Network Theory which was held in London.

He gave a paper on circuits with negative resistance elements at the symposium. 

The present major annual symposium of the Circuits and Systems Society (ISCAS) evolved from that 1971 symposium during which Tellegen presented his paper.

Tellegen therefore Inspired the major symposium of the Circuits and Systems Society (ISCAS) which is held annually.

8. Tellegen Was Professor Extraordinary of Circuit Theory at Delft University

Tellegen was professor extraordinary of circuit theory at the University of Delft for 20 years as from 1946 to 1966.

Circuit theory can be explained as a collection of interconnected components in the context of electrical engineering and electronics.

The process of finding the voltages across, and the currents through, all network components is what the study of circuit theory encompasses.

Some of the scholars who received their doctorate degrees working with Tellegen include Adams, Bordewijk and Duinker.

9. Tellegen Held Leadership Positions in Major Organizations in His Field

Tellegen held various leadership positions in notable organizations in his field of specialization.

 He was president of the Dutch Electronics and Radio Society as from 1942 to 1952 which made him an honorary member of the society for ten years.

He was the chairman of the Dutch Committee of the International Scientific Radio Union for 12 years as from 1948 to 1960.

He was the vice-president of the committee from 1952 to 1957; a period of five years.

He was vice-chairman of the Dutch Committee of the International Scientific Radio Union which was charged with circuit theory aspects.

10. Tellegen Received Various Awards and Recognitions

In 1953, Tellegen was made an honorary life member of The Australian Institute of Radio Engineers.

One year later in 1954, the Royal Dutch Institute of Engineers awarded him the Research Prize of the Royal Dutch Institute of Engineers.

He was awarded the Fellow Award of the IEEE and the IEEE Edison Medal in 1955 and 1973 respectively.

His creative career of significant achievement in electrical circuit theory, including the gyrator formed the main consideration for these awards.

In 1960, he was elected a member of the Royal Academy of Sciences of the Netherlands, The University of Delft conferred on him the degree of doctor honoris causa in technical sciences in 1970.