German Wikipedia lists Transistors according to EN 60617-2 with the symbol

Transistor in Wikipedia

I wonder whether this symbol is correct, or it's actually the old one.

I don't have the standard available, but in most cases, EN 60617-2 is trying to simplify the symbols. Therefore I would expect

  • no circle
  • no pin descriptions (B, C, E)

Expected symbol

Other transistors in that list do neither have a circle nor letters.

Can someone with access to an authorative reference clarify on how to design it correctly?

  • 1
    I believe that under EN 60617-2, the circle is only used when the transistor is in a metal case which is connected to one of the pins (like a TO-18), and the connection between the pin & the case is indicated by a dot where the pin passes through the circle - otherwise it's the base symbol without the circle. – brhans Aug 30 '17 at 21:59
  • @brhans: then the circle would make sense, I agree. – Thomas Weller Aug 30 '17 at 22:02
  • Your linked page labels the first symbol as "NPN-Transistor mit Gehäuse", so I think it's agreeing with @brhans. Why there's no symbol given for "Transistor ohne Gehäuse", I can't say. – The Photon Aug 30 '17 at 22:11
  • 2
    Maybe relevant, p. 81. – The Photon Aug 30 '17 at 22:18
  • In our schematics transistors are drawn the second way. I'd expect that Mentor Graphics use standardized symbols. But I also don't have access to the standard sadly. – Arsenal Sep 4 '17 at 14:38
up vote 1 down vote accepted

It seems a few things are coming together...

a) wrong part of the standard

I have bought EN 60617-2, just for finding out that the transistor is not listed. Part 2 only covers "symbol elements, qualifying symbols and other symbols having general application", which does not include the transistor.

The symbols listed in my part of the standard all have numbers in the form 02-xx-xx, so I assume that 02 refers to part 2 of the standard.

When you read on in this answer, you'll find that the transistors have 05-xx-xx. This would match the title of part 5, which is "symbols for semiconductors and electric tubes", so only EN 60617-5 could be an authorative reference.

b) symbols on Wikipedia

First, only for some symbols, the reference to EN 60617 is mentioned, e.g. for the LED, which has the symbol number 05-03-02:

LED according to EN 60617

For the transistor, such a hint is not present, which is a first indicator that it is possibly not an EN 60617 symbol:

Transistor according to unknown standard

Instead, it's likely a symbol of the former standard DIN 40900.

c) the correct symbol

In the comments, The Photon pointed out that in a reference manual, the NPN transistor has symbol number 05-05-02 and the PNP transistor 05-05-01:

Transistors according to EN 60617

As pointed out by brhans in the comments already, the latter only has a circle, because the housing is connected to the collector, otherwise it would be omitted as well.

This would also match the Wikipedia entry for Transistor which uses the symbols

NPN Transistor in Wikipedia

for NPN transistor and

PNP Transistor in Wikipedia

for PNP transistor, unfortunately without mentioning where that symbol comes from.

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