Compared to other countries, the history of early semiconductor manufacture in France is somewhat obscure. Finding original devices and contemporary data books or sheets about them is difficult. However, there are some other sources:

            You can view and download those in full from the links above.

The start of the French industry was simple because it was dominated by two commercial firms:

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.
  • 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.

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

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

Je cherche des exemples des premiers transistors français et des diodes semi-conductrices, énumérés ci-dessous dans le texte. Je cherche aussi des bouquins de donnéés contemporaines. 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 and was not followed by commercial exploitation. A French subsidiary of the US company Westinghouse, led by a German physicist, invented the point-contact 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

Transistron

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


The first transistors made by CSF, 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, up to about 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

wanted CSF transistors

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 thus 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

SFT101 transistor
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.

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

SFT114 transistor
SFT352 transistor

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

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

SFT125 transistor
SFT131 transistor

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

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

SFT213 transistor

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


I'm rather short on information about CSF germanium diodes. There is a 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

SFD108 diode

CFTH started making silicon point-contact microwave diodes in the early 1950s. My image shows a TH8121B in the classic plug-in cartridge with its protective anti-static casing. This type is one of a series of ten numbered 8021, 8121, 8023 and 8123 plus various suffixes. The part numbers ending in 21 are equivalent to the American 1N21, and those ending in 23, to the 1N23.

CFTH microwave diode
CFTH detector diode

CFTH also made four "low-level detector" silicon diodes: TH8031, TH8032, TH8131 and TH8132. I think they were equivalent to 1N31 and 1N32. I believe they look like the above 8x2x types but I would be interested in information about or examples of them. If you know where I might obtain any of these, please

CFTH then made many germanium and silicon diodes, although I'm unsure of the chronology but the following are listed in the 1961 D.A.T.A book (see above). There are several series:

  • 1F2 to 4F2 which D.A.T.A. list under 'miscellaneous diodes'
  • 10J2 to 18J2 which D.A.T.A. list under 'rectifiers'
  • 10R2 to 15R2 which D.A.T.A. list under 'rectifiers'
  • 11R4 which D.A.T.A. list under 'rectifiers'
  • 12P2 to 19P2 which D.A.T.A. list under 'diodes' and I guess are point-contact diodes
  • 14P1 to 16P1 which D.A.T.A. list under 'diodes' and I guess are point-contact diodes
  • 11Z4 to 17Z4 which D.A.T.A. list under 'Zener diodes'
  • various higher-numbered types in the above series e.g., 26P1, 215Z4 etc
  • 21RIA to 24RIA which D.A.T.A. list under 'rectifiers'
  • 1N21 to 1N1143 with many gaps
  • THP71, THP119, THP800 to THP805, THP911 to THP915, THP917, THP921

The image shows a SESCO-branded 18J2 in a MAZDA RADIO box. I have a similar 16Z4. I would be interested in information about or examples of the THP series diodes. If you know where I might obtain any of these, please

18J2 diode

36T1 transistor

For what seem to be political reasons, CFTH got off to a relatively slow start in transistors. 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. They also made transistors in a series that had a numeric prefix of two or three digits followed by the letter 'T' and then a numeric suffix. The 1962 D.A.T.A. book (see above) lists the following series:

  • THP35, THP36, THP45 to THP47, THP61 and THP62, THP106
  • 1T3 to 4T3
  • 10T2 to 12T2, 26T2, 28T2 and 29T2
  • 17T1, 18T1, 25T1, 26T1, 28T1, 35T1 to 39T1, 44T1, 64T1, 65T1 and 82T1
  • various groups of 2N numbers from 2N43 onwards

On the left I show a 36T1 and on the right a 2N186.

Information from the radiomuseum site shows that, by about 1960, they were also using in commercial radio manufacture:

  • 941T1, 942T1, 965T1, and 987T1 to 992T1
2N186 transistor
44T1 transistor

On the left is a Sesco 44T1 in the same TO-5 case with integral heatsink as the SFT131 above. I am keen to obtain original examples of CFTH transistors and diodes, especially:

  • Any transistor or diode in the TH or THP series
  • 1T3 to 4T3
  • 10T2 to 12T2, 26T2, 28T2 and 29T2
  • 17T1, 18T1, 25T1, 26T1, 28T1, 35T1

If you know where I might obtain any of these, please


La Radiotechnique logo

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' other two European manufacturing subsidiaries, Mullard and Valvo. La Radiotechnique used the logo shown on the left 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 OC28

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.

La Radiotechnique OC29

French ADZ11 transistor

Mark's Web page does not mention 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!

French OC139 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

Radio Prim transistor

ASY26 transistor

I won't show any later types, except this SESCOSEM ASY26 which displays their stylised transistor logo. However many rather pedestrian germanium types with pro-Electron numbering were made by COSEM, SESCO and SESCOSEM. Examples can be found on eBay, although vendors often specify the incorrect manufacturer, not surprising considering the messy history shown above.


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

SESCO diode





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