Valvo logo

The German company Valvo was an old and well-established company that made renowned vacuum tubes. Their history is not very well documented on the Web, at least not in English, but a starting point is this page on the German wikipedia (translated by Google), and some more detail is given on this Facebook page.

These reveal that the company was founded in 1924 in Hamburg, and in 1927 became part of the Philips group. Neither article mentions semiconductors in any detail, their focus being on vacuum tubes. However, the relationship between Philips and its subsidiaries Mullard (in England), Valvo (in Germany) and La Radiotechnique (in France) appears to have been quite free. (There was also Amperex in the USA, but this was essentially a sales channel). The subsidiaries had their own research facilities (of course Philips had major laboratories in Eindhoven) and may have been able to develop devices that went on to be manufactured across the group. If you know more about how this worked, please Apparently Valvo was split in the 1980s and sold in 1999.

Valvo did not print their logo on semiconductor devices: they just printed the word VALVO in capital letters. I am seeking to buy or trade for germanium transistors and diodes made by Valvo, especially the types 100.O.C, OC10 to OC12, and OC50 to OC51, but also some others. More details are given below.

The primary Valvo data book that I possess is the Valvo-Handbuch "Halbleiterdioden und Transistoren". I have copies dated 1958 and 1962. I also have a booklet "Dioden Transistoren" dated 1960. I am interested in other original data books or sheets for any of their semiconductor devices.

If you know about them, or have have some devices for sale or trade, please


The earliest transistors made by the Philips group as a whole are described in several places on the Web, although the Philips pages on their company history seem to have disappeared, perhaps because of the change to NXP Semiconductors. On Google, there is a site by Mark Burgess that covers early Philips semiconductors, revealing that their first transistors were the point-contact types OC50 and OC51. It is unclear which manufacturers in the Philips group really made these and which simply marketed them: certainly Mullard made them, and I suspect that Valvo did too.

I have a number of OC51 transistors that I believe were made by Mullard, and they have no branding. If you know about Valvo examples, or know how I can obtain some, please

wanted transistor

The first junction transistors made by the Philips group were the trio OC10 to OC12 in small plastic cuboids. Again it is unclear which manufacturers in the Philips group really made these and which simply marketed them, and again I have some and they are unbranded. If you know about Valvo examples, or know how I can obtain some, please

OC71 and OC71A transistors

Valvo went on to manufacture the next set of transistors from the Philips group: the OC70 to OC72 AF amplifier types from 1954. Valvo also made the variant shown : OC71A, and added this suffix to a few other types too. I don't know what it signifies, possibly a tighter gain selection. Again I have no original documentation for this so if you know how I can obtain some (or a scan of it), please

100.O.C transistor

Another puzzle exists around the creation of Europe's first power transistor, the type 100.O.C. Mark Burgess states that this was "released by Valvo in October 1954" and became the wider Philips group type OC15. In the USA it was marketed as the 2N115. I have the example shown: it bears no branding and all the printing on it is in English. Consequently, I'm unconvinced that Valvo made this. I have no original Philips-group documentation for either 100.O.C. or OC15: it might help resolve the question. If you know how I can obtain some (or a scan of it), please

Valvo OC16 transistor

The first commercial power transistor in Europe was the OC16, in a stud package, released about 1956. It can be found branded Mullard and Valvo, as well as unbranded, which I take as indicating Philips production in the Netherlands.

There exists also a more primitive version of the OC16, with leads emerging from the top. It is shown on my Mullard page. This is always unbranded in my experience.

Valvo went on to issue own-branded versions of the majority of early semiconductor devices in the Philips-group range. It is interesting to try to compare Valvo's range with that of Mullard. The primary Valvo source for comparison that I have readily available is the Valvo-Handbuch "Halbleiterdioden und Transistoren" dated 1962, but I have supplemented it with other data. For Mullard types I used the "Mullard Maintenance Manual" 1961, the "Mullard Designer's Guide" May 1964, and other earlier sources plus Mullard types in my possession. I only compare the germanium series plus a few early silicon types: AA, AC, AD, OA, OC and BCZ. The earliest types OC50/51/10/11/12 were obsolete by the time of the documents I used. (I had to write some software to generate this table because the html coding was so onerous and error-prone).

Type Valvo Mullard        Type Valvo Mullard        Type Valvo Mullard        Type Valvo Mullard        Type Valvo Mullard
2-OA72 AF114 BCZ12 OC23 OC77
2-OA79 AF115 BCZ13 OC24 OC79
2-OC26 AF116 OA5 OC25 OC80A
2-OC30 AF117 OA6 OC26 OC81
2-OC72 AF118 OA7 OC28 OC81D
2-OC74 AF124 OA9 OC29 OC81DM
AAZ12 AF125 OA10 OC30 OC81Z
AAZ13 AF126 OA31 OC35 OC82
AAZ15 AF127 OA47 OC36 OC82D
AAZ17 AFZ11 OA70 OC41 OC83
AC107 AFZ12 OA72 OC42 OC84
AC128 ASY26 OA73 OC43 OC122
ACY17 ASY27 OA79 OC44 OC123
ACY18 ASY28 OA81 OC45 OC139
ACY19 ASY29 OA85 OC46 OC140
ACY20 ASY67 OA86 OC47 OC141
ACY21 ASZ15 OA90 OC57 OC170
ACY22 ASZ16 OA91 OC58 OC171
AD140 ASZ17 OA95 OC59 OC200
AD149 ASZ18 OA200 OC60 OC201
AD161 ASZ20 OA202 OC70 OC202
AD162 ASZ21 OA210 OC71 OC203
ADY26 ASZ23 OA211 OC72 OC204
ADZ11 AUY10 OAZ group OC74 OC205
ADZ12 BCZ10 OC20 OC75 OC206
AF102 BCZ11 OC22 OC76 OC207

"OAZ group" comprises OAZ200 to OAZ213 Zener diodes in SO-2 metal-over-glass outline.

A possibly difficulty with identifying Valvo devices is that many came in small cartons clearly marked "Valvo". However the devices inside may be unbranded. This raises the question of whether they were really manufactured by Valvo, or whether they are Valvo-boxed Philips production.

There are some interesting differences visible in the above table:

If you know that any of the above is incorrect, (which is quite possible...), please

Obviously, the interesting types are the ones that Mullard (and probably Philips too) did not manufacture:

wanted Valvo matched pairs

I don't have any of the Valvo matched pairs (like 2-OA72 or 2-OC30). I am seeking examples of these, by Valvo or Mullard.

Valvo BCZ10 silicon transistor

Here is the BCZ10 silicon PNP general purpose transistor. The group BCZ10 to BCZ12 shares with the OC200 group and the rather obscure BCY10 to BCY12 the oddity of being the only silicon transistors in the SO-2 metal-over-glass encapsulation.

Valvo BCZ13 silicon transistor

This BCZ13 is an oddity. It is a silicon PNP transistor intended as an AF amplifier. The only other transistors that use this Philips-group subminiature can are the germanium OC57 to OC59 intended for use in hearing aids. It is not printed VALVO, but the case is very small, and the examples of OC57 to OC59 that I possess are also unbranded.

Valvo OC79 germanium transistor

Here is the OC79 germanium PNP low power AF amplifier/driver.

OC47 Valvo transistor

Here are some unused OC47s in original packaging. I don't have Valvo-branded OC46 or OC80A transistors. I am seeking examples of those.

Valvo OA9 diodes

Here are two Valvo-branded OA9 diodes. I am seeking examples of OA72.

Valvo OCP70 phototransistor

Here's an interesting device: it's the germanium phototransistor OCP70. This is included in the Philips Pocketbook for 1959, but not in my Valvo data books for 1958 and 1960. However, all the examples I have seen are unbranded except these ones. The rightmost one is printed VALVO. It also bears a stylised crown containing the letters BWB and a number, seen on the middle one. This stands for "Bundesamt fuer Wehrtechnik und Beschaffung" which translates as "Federal Office of Defense Technology and Procurement". I have some that are not marked VALVO, instead they just have the BWB mark and a capital V, seen on the leftmost one, which stands for "Verteidigungsgeraetenormen" or "Defense equipment standards". This means that these devices meet military specifications. This is intriguing, as the type OCP71 seems to have superseded OCP70 rather quickly. I don't have any Valvo OCP71s, although I have a number of Mullard ones.

Valvo germanium diodes

For completeness, here is an image to show that Valvo made germanium diodes in both of the main Philips-group encapsulations (single-ended and double-ended glass capsules). I don't have any in other outlines, notably the OAZ Zeners in the SO-2 metal-over-glass capsule.