|
Hi Bernd,? Gee I did see it many times in the past 25 years ago but I was always focussed on doing things rather than keeping track on trivia and standards. Now you made me dust off my old books to dig it up. Anyway the circle is one of usual elements used to describe essential feature or function of a component. It's origins are very old indeed - anyone recalls vacuum tubes? Back to your question, you will find this in:? IEEE Std 315-1975 (Reaffirmed 1993) ANSI Y32.2-1975 (Reaffirmed 1989) CSA Z99-1975 In particular, check for "envelope" or go to section A4.11 and
1.10 The circle is optional anyway and specially these days it get omitted because?number of discrete transistor is nothing compared to number of integrated ones. (My usb flash drives are 8Gb, that is a lot of transistors right there, not to mention processors, ram etc). This is why some think this is what old people used to use. The only time this made practical sense with solid state devices was when emphasizing that certain things are discrete, or grouped together (matched pair or device with built in temperature sensor etc.) or when indicating grounding/shielding (RF) or cooling (heatsink) of the transistors. Ivica Kvasina From: Bernd Wiebus To: kicad-users@... Sent: Tuesday, June 12, 2012 10:04:47 AM Subject: Re: [kicad-users] Re: Comments About Eeschema
?
Hello Ivica.
> circle on transistor symbol is used to indicate that this is discrete > component (individually packaged transistor - has nothing to do with > form or shape of package). transistors without circle therefore > indicate that they are part of IC circuit (look at schematics of opamp > or gates for example). Nice to know and would make sense. Can you give me a point to the official source of this statement? I want to discuss it with the local EN-standard supplier here, because the lack of this information in his papers. So here you find this fat single (mostly MOSFET) Transistors normally without circle in the schematics. With best regards: Bernd Wiebus alias dl1eic |
