Centenary birthday bash for the birth of electronics

Developed one hundred years ago by Sir John Ambrose Fleming who founded UCL's Department of Electrical Engineering, the thermionic valve led to the development of radio, television, telephones and early computers.

Journalists are invited to attend a centenary conference, 'The life, work and legacy of John Ambrose Fleming', on 1 and 2 July 2004. Run in collaboration with the Institute of Electrical Engineers, the conference will address all areas of electronics and electrical engineering, including technical and social aspects, from the mid-19th century to the present day and beyond.

Professor Hugh Griffiths, Head of UCL's Department of Electronic and Electrical Engineering, says:

"Fleming is very much an unsung hero amongst British electronics pioneers. He made a significant contribution to the development of modern-day communication technologies yet bitter disputes have raged for many years over the true fatherhood of devices such as the radio. We know speech transmission using modulation of radio waves was demonstrated in 1902 but very little progress was made until the perfection of the thermionic valve, which allowed a clear amplification of the signal."

In 1899 Fleming became a consultant to the Marconi Company in addition to his duties at UCL. At this time wireless, as radio was then known, was still in its infancy and Marconi was continually making improvements in transmission distance. In 1901 he succeeded in sending a message across the Atlantic. Fleming became quite absorbed in the subject and even designed the transmitter that made the first transatlantic transmission. Fleming recognised that the major problem preventing improvements being made was that of detecting the signals themselves. In these early days the coherer was the main form of detector and it was very insensitive. With this in mind Fleming began investigating the possibility of using the 'Edison effect' to rectify the radio waves and thereby act as a detector.

Thomas Edison had noticed in 1880 that when the bulbs of his early lamps blackened with use, the positive side of the filament cast a 'shadow' in the blackening of the bulb. He inserted a metal plate in one of his bulbs and found that a current would flow if the plates were made positive with respect to the filament but not if the polarity was reversed.

Recalling these experiments Fleming was able to develop a method of rectifying electrical oscillations - that is making electricity flow in only one direction. It then took less than a month for the patent of the thermionic valve to be filed on 16 November 1904.

UCL's Department of Electronic and Electrical Engineering will also be open to the public on 30 June, where visitors will be able to see a large collection of experimental valves and original equipment as well as research currently being done by the department. Guest lectures on the life of Fleming will also be taking place throughout the event.

Please contact Judith H Moore in the UCL press office on +44 (0)20 7679 7678 for further details about the conference and how to register.

HIGH RESOLUTION IMAGES OF THE THERMIONIC VALVE AND SIR JOHN AMBROSE FLEMING ARE AVALIABLE ON REQUEST

Notes to Editors

For further information please contact:

Judith H Moore
Media Relations Manager
University College London
Tel: +44 (0)20 7679 7678
Mobile: +44 (0)77333 07596
Email: judith.moore@ucl.ac.uk

Further details about the conference can be found at: http://www.ee.ucl.ac.uk/Fleming/Conf

About the thermionic valve

In the valve, electrons flow through a near-vacuum - where they experience hardly any resistance - between a heated cathode that emits electrons, and a positively charged anode, which attracts them. Therefore, the electrons flow in only one direction, giving the rectification property that was the basis of Fleming's invention. When a third electrode - a grid - is introduced between the cathode and the anode, a negative voltage on the grid will repel the electrons from the cathode, and hence control the electron flow to the anode. This is the basis of the triode valve, which can achieve amplification since small changes in grid voltage cause large changes in current flow from cathode to anode.