The earliest semiconductor devices used idiosyncratic naming and numbering conventions determined solely by their manufacturers. However this did not last, and various national and international standards came into existence across the world in the 1960s.
In Europe, the Pro Electron type designation and registration system for active components was set up in 1966 in Brussels, Belgium. In terms of the early types of diodes and transistors, the system was:
- An initial letter : A for germanium or B for silicon.
- The second letter :
- A for a low-power/small-signal diode
- B for a varicap diode
- C for a small signal transistor
- D for a high-power, low-frequency transistor
- E for a tunnel diode
- F for a low-power, high-frequency transistor
- L for a high-frequency, high-power transistor (for transmitters)
- S for a low-power switching transistor
- U for a high-power switching transistor
- Y for a high-power rectifying diode
- The characters following the first two letters form the serial number of the device. Those intended for domestic use have a three-digit number, but those intended for commercial or industrial use have a letter (usually Y or Z) followed by a two-digit number.
Devices with such a standardised type number may be made by multiple manufacturers.
As well as standardised pro-Electron numbering, most of these types use a standardised JEDEC device packaging, or 'outline' as it is known. Diode shapes were specified in the DO series of outlines, and transistors in the TO series. However, a number of types with pro-Electron naming use earlier, idiosyncratic, outlines. The majority of commercial devices fall under one of only a few outlines. These outlines are fully specified in JEDEC documents held in their archive, with separate pages for diodes and transistors. A login is necessary, but anyone with a bona-fide reason can register.
I'm mainly interested in germanium devices, so just for fun (and to increase my knowledge) here are the types, starting with the lowest-numbered, in each of the above categories. I've tried to include all the types in each category except where there are too many. The documentation that I used to compile this is old and not entirely reliable. In particular there are several lesser-known manufacturers from the remoter parts of Europe that may have made such types, but they are rarely seen and I may have missed some types. If you see errors or omissions, please do inform me.
I am seeking examples of a number of these: I have indicated them in red. NB I usually only want manufacturer-branded examples. (This does not mean that I possess all the rest, I have just selected those that I find particularly early or unusual). If you can tell me where I might find any, please
Low-power/small-signal germanium diodes:
Most of these are point-contact diodes in miniature axial glass outline.
- AA129 by Philips/Mullard/Valvo, The Netherlands/England/Germany - a transistor rewired as a diode, in the older SO-2 glass outline.
- AA130 and AA131 by Ei NIS.
- AA132 to AA140, AA142 by AEG-Telefunken.
- AA143 and AA144 by Intermetall, Germany.
Industrial germanium diodes:
Germanium rectifying diodes:
Germanium industrial rectifying diode:
The only one seems to be:
But I am suspicious about the very similarly numbered AAY10-120.
Germanium varicap diodes:
The defined type is ABnnn, but there are none that I can find.
Low-power/small-signal germanium transistors:
Industrial low-power/small-signal germanium transistors:
- ACZ10 by AEG-Telefunken in the older SO-2 glass outline with metal heatsink fin.
High-power germanium low-frequency transistors:
Industrial high-power germanium low-frequency transistors:
Germanium tunnel diodes:
Germanium industrial tunnel diodes:
Low-power germanium high-frequency transistors:
and many more up to AF439 but with many gaps in numbering. Some of the more interesting are:
A number of the higher-numbered AF types are RF types in plastic encapsulation.
Industrial germanium high-frequency transistors:
Germanium high-frequency, high-power transistors:
Germanium industrial high-frequency, high-power transistor:
In fact, this is only a 250 mW type, so why it fits in the category L is a bit unclear.
Industrial germanium switching transistors:
I don't know why, but there are no non-industrial switching transistor types of the form ASnnn.
High-power germanium switching transistors:
These are uncommon, and all the examples I have seen are unbranded.