> >> Unless someone knows what the current IEC or ANSI standard symbol is, =
I
> >> think I'll probably just go with what I know best (and seems most comm=
on
> >> in the schematics I've seen)) which is the T shaped one.
> > My colleague told me there is an IPC standard for this. Maybe
> > IPC-2612.
> > http://www.ipc.org/TOC/IPC-2612.pdf (table of contents only,
> > you have to pay for the standard. Right now I do not have
> > access to this document.
....
>=20
> I have the older version here, I might pay to grab the new one at some
> point.
> I guess as long as you are consistent within your company's schematics
> then it doesn't matter much about the choice, as long as it's reasonably
> well known.
> I may go with the triangle shape though, now you mention it I do seem to
> recall seeing it quite a lot. Funny how the brain filters out things you
> are not used to, I have probably "seen" the T symbol more often as it is
> what I am used to using.
> This was just as much a curiosity to see how things had progressed as
> far as the standardisation of symbol/designators/bus wiring etc goes. It
> has certainly got a lot better in recent years, I have worked with a lot
> of vintage (mainly audio) equipment, and deciphering some of the older
> schematics is real detective work at times :-)

I have just looked in our copy of BS7845:1996 "Guide to the use of BS3939 a=
nd BS EN 60617 'Graphical Symbols for Diagrams'" (which covers more than ju=
st electric/electronic schematics) and although it doesn't specify a symbol=
 for a power connection, it shows three symbols for ground and frame connec=
tions, the familiar three horizontal bars for 'earth or ground general symb=
ol', the single horizontal bar with three diagonal 'hatching' lines (the te=
rm they use) under it for 'Frame or Chassis', and an inverted T with the ho=
rizontal line thicker than the connection line. This seems to be an alterna=
tive to the hatched symbol for frame or chassis, as they have a note agains=
t the hatched one "The hatching may be completely or partly omitted if ther=
e is no ambiguity. If the hatching is omitted, the line representing the fr=
ame or chassis shall be thicker, as shown".

Then in other places they have some example schematics where a 'normal' ver=
sion of this is used, and labelled with the supply voltage. I a couple of p=
laces the thick line is extended to one side so a bypass capacitor can also=
 be 'hung' from the thick line, rather than being component connected to th=
e vertical line. In this situation both the connections to the thick line h=
ave the 'normal connection dot' to show it is a valid connection. There is =
also an inverted one showing a negative supply voltage.

I haven't continued on to look through BS EN 60617-2:1996 (IEC 617-2:1996) =
as this is a rather large document to search (our printed copy is about 35m=
m thick).

And to head of the ribald comments ... here BS stands for British Standard,=
 not something 'naughty', and EN is the European Standard, which for this s=
tandard is considered the British Standard (the marvels of a harmonised Uni=
on ... ).
--=20
Scanned by iCritical.

--=20
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