Compared to other countries, the history of early semiconductor manufacture in France is somewhat obscure. Fortunately for me, it has already been documented by another enthusiast, Mark Burgess, on this Web page. I therefore will avoid repeating his information as much as possible.

I am seeking a number of early French transistors and semiconductor diodes, as listed below in the text. If you know where I might obtain these, please

Je cherche exemples des premiers transistors français et des diodes semi-conductrices, énumérés ci-dessous dans le texte. Si vous savez où je pourrais les obtenir, prière de


There is one momentous historic event that took place in France, although it went unrecognised at the time. A French subsidiary of the US company Westinghouse, led by a German physicist, invented the transistor completely independently of Bell Labs.

This link provides details of this amazing achievement.

I am seeking examples of the transistron. If you know where I might obtain any, please

wanted LCT transistors

Mark's article does not give exact chronology, but states that the Laboratoire Central de Télécommunications (LCT) produced two point-contact transistors, types 3698 (switching) and 3768 (general use). These used the typical 'type 1' plug-in cartridge case originated by Bell Laboratories in the USA.

LCT also made some early junction transistors, for example the type 3604 and 3609.

I am very keen to obtain examples of any LCT transistors. If you know where I might obtain any, please

wanted CSF transistors

Possibly the first commercial junction transistors in France were made by the Compagnie Générale de télégraphie Sans Fil (CSF), although they did not seek a license from Bell Laboratories nor any arrangement with RCA unlike many of the early manufacturers. Their first transistors, the TJN1 and TJN2, were produced by the Recherches Physico-chimiques laboratory (RPC) at Puteaux. They went on to make a few more types in the TJN series, for example TJN6 and TJN7, and one power transistor: TJN100.

I am very keen to obtain examples of any TJN transistors. If you know where I might obtain any, please

La Radiotechnique logo La Radiotechnique OC28

Another early French manufacturer was La Radiotechnique, which was owned by Philips of the Netherlands, the biggest manufacturer of germanium transistors in Europe. I do not believe that La Radiotechnique was as important as Philips's other two major semiconductor manufacturing subsidiaries, Mullard and Valvo. La Radiotechnique used the logo shown on its thermionic valves/tubes: a transmitting tube with the letters RT inside it. After more than 30 years of collecting, I have only ever seen this appear once on a semiconductor, the OC28 germanium power transistor on the right. However I also have an IC of theirs where only the letters RT are used.

If you know anything about La Radiotechnique germanium semiconductors, or where I could get some, please

La Radiotechnique OC29

Well, just like buses ... only a few weeks after publishing the above I was able to buy another RT germanium power transistor, OC29 this time, on eBay.

French OC139 transistor French ADZ11 transistor

Some information that seems to be missing from Mark's Web page is that a small number of germanium transistor types, branded for the English company Mullard, were manufactured in France, as proven by printing on them. I show an ADZ11 power transistor and an OC139 in the classic glass tube. In fact, Philips/Mullard had factories in very many countries, but only a few seem to have made semiconductors. In France, Philips used the factory of the Compagnie Industrielle Française des Tubes Electroniques "CIFTE", 1 Place Herold, Courbevoie Seine, just outside Paris. I was informed of this by a correspondent, who also provided me with an explanation of Philips' device codes, now listed on the Web.

Unfortunately, the codes on my transistors, 3ZkY and LkZ, do not match in any obvious way the information in that document!

SFT101 transistor

By 1959 CSF had dropped the TJN series and was producing PNP germanium junction transistors in the SFT series (although in fact there is a dot between the SF and the T: SF.T) and diodes in the SFD series. The earlist of these transistors use bell-shaped cans, painted black. I am keen to obtain original examples of such transistors, for example SFT101, SFT102 and SFT103. If you know where I might obtain any, please

SFT107 transistor

Later examples in the series such as this SFT107 use a tall 'top hat' shape, still painted black, and with a curious double-edge to the rim.

SFT114 transistor

Some low-numbered SFT power transistors were made, such as this SFT114 in a circular domed case just over 2 cm in diameter. Early examples are marked CSF, but my example was in SESCO packaging (see below).

I seek examples of any transistors branded CSF. If you know where I might obtain any, please

SFT352 transistor

Later SFT series types such as this SFT352 use a fairly standard TO-1A package, still painted black.

SFT125 transistor

This 350mW SFT125 is not painted but still has the double-rim.

SFT131 transistor

Some such as this 1.33 Watt type SFT131 have a heatsink fin fixed around them.

SFT213 transistor

This SFT213 employs the standard TO-3 package, although it is branded CSF which suggests that it is an early example.

One aspect of the SFT series that puzzles me is that an apparently-equivalent EFT series exists, made by the company IPRS Baneasa in Romania. How this commercial arrangement came to be is a mystery to me, if you know about it, please

Radio Prim transistor

I bought these power transistors in original boxes on a well-known auction site. The vendor stated that they were sold by Radio-Prim, and were similar to SFT114. I know little about Radio-Prim, the Radiomuseum site lists some valve/tube radios that they made, but no semiconductors. If you know how they came to sell what seem to be re-badged CSF transistors, or have other information about their semiconductors, please

2N186 transistor

The other major French manufacturer of semiconductors was Compagnie Française Thomson-Houston (CFTH) who were in fact a subsidiary of the General Electric Company of the USA. For what seem to be political reasons, CFTH got off to a relatively slow start in semiconductors. In 1956 they advertised a single power transistor, TH8501, and by 1958 they had started their own THP series but were also manufacturing GE types from the American 2N series. My image shows a 2N158 made by CFTH.

wanted transistor

I am keen to obtain original examples of CFTH transistors in the TH and THP series, especially TH8501, THP35, THP36, THP45 to THP47, THP50 to THP52, THP61 and THP62. If you know where I might obtain any of these, please

36T1 transistor

CFTH also made transistors in a series that had a numeric prefix of two or three digits followed by the suffix T1. Examples are 36T1 and 991T1. The earliest examples use black 'top hat' cans with a wide flange; later examples employ black TO-5 cans. I am looking for early examples.

SFD108 diode

I'm rather short on information about French germanium diodes. There is a CSF series of SFD types: my image shows an SFD108 (much magnified). These seem to be mostly boring miniature glass point-contact types and often just bear coloured stripes as identification. There must exist more interesting early types.

If you know about any, please

Things subsequently became complicated in terms of company structures:

  • In the mid 1950s CSF created a semiconductor manufacturing wing called the Compagnie Générale de Semi-conducteurs (COSEM).
  • In 1961 CFTH formed a joint venture with General Electric, the Société Européenne des Semi-Conducteurs (SESCO).
  • In 1966 CFTH merged with Hotchkiss-Brandt to form Thomson-Houston-Hotchkiss-Brandt (soon renamed Thomson-Brandt).
  • In 1968 the electronics business of Thomson-Brandt merged with CSF to form Thomson-CSF.
  • In 1969 SESCO and COSEM merged to form SESCOSEM.

COSEM, SESCO, Thomson-CSF and SESCOSEM brands can all be found on germanium transistors. I'm unsure about Thomson-Brandt.


SESCOSEM used a stylised transistor logo,as shown on this ASY26.

  • In June 1987 the Italian company SGS (Società Generale Semiconduttori) merged with Thomson Semiconducteurs to form SGS-Thomson.
  • SGS-Thomson was renamed STMicroelectronics in May 1998.

SGS Thomson made germanium devices, and eBay usually has some that are claimed to be from STM, however this last is probably too late to be of interest to historic device collectors.

SESCO diode

This diode is a puzzle. It is simply printed SESCO, nothing else. No part number in particular.

If you have data or information about it, please

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