Likewise most circuits I have show a circle. Personally I don't really
care, a transistor is a transistor regardless; Easy enough to tell
what is it with or without, or for that matter with lines intersecting
Providing it's got the arrow on the emitter I can work out what it is :-)
From the very dim and distant past, I was still at school, interested in
Amateur Radio and electronics I bought my first communications receiver,
an Eddystone EC10. It used several OC171 Germanium transistors. The
circuit diagram for the EC10 depicted the shield to the can as a short
dotted line with a connection to ground. I don't think I've seen a circuit
depicting the can connection that way since.
If you like a bit of vintage circuitry the EC10 circuit is here:
Brought back a few memories. The EC10 was a nice Rx for it's time.
Andy
On Tue, 12 Jun 2012 15:40:39 -0700 (PDT)
Cirilo Bernardo <cirilo_bernardo@...> wrote:
Hi Robert,
?Take Bernd's? advice regarding the circles since he has a copy of the standard.? (The last copy I had is so old that the circle only denoted the physical envelope, not necessarily a conductive package.) Also, from personal experience, a schematic with a lot of transistors really gets cluttered by the circles. But having said that, as I wrote before, the schematics I have from work still have that circle.
- Cirilo
________________________________
From: Bernd Wiebus <bernd.wiebus@...>
To: kicad-users@...
Sent: Tuesday, June 12, 2012 7:51 PM
Subject: Re: [kicad-users] Re: Comments About Eeschema
?
Hello Robert.
I will shrink
some components, so perhaps I should postfix the components with _SMALL
to eliminate clashes.?? Mainly I'll be shortening pin lengths.
Yes, i used this postfix method in my first attemp to create a library
when i noticed that my symbols were much too big......
Is it OK in IEC60617 to have circles around transistors??? I notice that
a circle is included when one of the electrodes is connected to the
envelope (and then you're supposed to show the connection with a dot),
but what about where there is no connection?
Of course, EN60617-5 contains as No. 05-05-02 only one example of a
transistor encapsulated with a circle for a housing and a dot for the
connection.
Furthermore EN60617-5 is modular, so it contains a lot of symbols of
typs of electric channels, intrinsic zones, multilpe gates and so on.
So you can create your fitting symbol for your transistor or diode.
But EN60617-5 contains no example of a single transistor housing as a
symbol....this circle just exist in this exampleNo. 05-05-02.
So No. 05-05-02 should not exist, or it implicides, that a circle is a
symbol for a (conductice) housing.
No. 05-07-01 and No. 05-07-02??do not fit in this system, too, because
they are symbols for a tube envelope, which can be steel, but used to be
glass or ceramic.
Now i am thinking about canceling the circles in the library. I used
them only for classic pipolar transistors. Theoretikal there should be
three alternative symbols for every transistor type: one without
housing, one with housing, but not connected, and one with a housing
connected to the collector (but what is with emitter connected
housings?) So it would be a bulky library with many seldom used symbols.
And i think, exactly this is the reason why the EN60617-5 is
modular.....
Today transistors with shielded housings are very uncommon. So it is
better to cancel the housings, and the few cases, where a housing is
importand, have to draw an extra circle around their transistors and tie
it where it fits.
?? I like having the circle because it shows at a glance that the part
has its own package, and by making part of the circle dashed one can
show at a glance that the tcomponent shares its package with other
devices (and therefore there will be fewer packages on the board).
By
way of example?? I've attached an image showing my own symbol for a
BC817DS, for which Yahoo Groups should provide a link.
Nice. About this way i didnt think yet.
Here the circle is mostly used by old people from the times when
transistors in round thin cans were common. Is also a taste of
nostalgie.
By the way: My EN60617-5 here, which is from 1996 and active, contains
44 pages. 3 pages pr?ambel, 15 pages about semiconductors and 26(!)
pages about tubes(!). ;O)
With best regards: Bernd Wiebus alias dl1eic
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