Schematics & standards
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From: Arfa Daily on 19 Jun 2010 05:10 "N_Cook" <diverse(a)tcp.co.uk> wrote in message news:hvhv1s$88b$1(a)news.eternal-september.org... > David Nebenzahl <nobody(a)but.us.chickens> wrote in message > news:4c1bd34c$0$2542$822641b3(a)news.adtechcomputers.com... >> Someone else made a comment in another thread here about weird >> schematics (like for home appliances). >> >> Wanted to get a small discussion going on that topic. My take: there are >> good and bad standards for schematics. Personally, I can't stand the >> ones that use rectangle shapes for resistors, instead of the traditional >> zigzag that [insert name of deity here] intended to be used. (And even >> here there are lots of variations, like old-fashioned schematics that >> took this symbol rather literally and sometimes had ten or twelve zigs >> and zags, as if an actual resistor was being constructed on paper). >> >> Likewise the wire-connecting/jumping convention: here I much prefer the >> modern approach, which is to use a dot for a connection and no dot for >> no connection, rather than the clumsy "loop" to indicate one wire >> jumping over another with no connection. >> >> Regarding resistor values: Who the hell came up with that new way of >> specifying resistance values, like "10R" "or 5K6" or whatever? And why >> use this system? I've always used the plain value of the resistance: 10, >> 56, 5.6K, 56K, etc. Simple, obvious, requires no interpretation. Is this >> some kind of Euro thing? >> >> In general, some schematics just look and feel nicer than others. A >> well-drawn schematic is a pleasure to read. A bad one--lines too thin or >> too thick, misshapen symbols, idiosyncratic interpretations, etc., just >> don't look right. >> >> Feel free to add your own schematic pet peeves here. >> >> >> -- >> The fashion in killing has an insouciant, flirty style this spring, >> with the flaunting of well-defined muscle, wrapped in flags. >> >> - Comment from an article on Antiwar.com (http://antiwar.com) > > > > How often have you come across compressed pdf-type schema or reduced > paper-based ones where the decimal point has disappeared , and there is no > kerning for dots, so you cannot infer a position for any dot position. > Replace R/K/M for the dot makes a lot of sense. > Yes, I'd go along with that. It is a far more sensible way of showing values, and I can't see anything counter intuitive about understanding it. I still prefer zig-zags for resistors, and if I'm drawing a quick 'sketch' of a diagram, I always still 'jump' the non-connected lines. However, when I'm hand-drawing a diagram properly, with nice straight lines and 'gridded' components, I always break one of the two crossing lines, where they break, so sort of the 'jumping over' convention, but without the actual bridge being drawn. I'm not sure where I first saw this, but schematics drawn like it, look quite nice. There's no question about whether lines do connect or not, and the brain fills in the little missing bit of the line without you having to think about it. Where lines do connect, they get a nice dot on them. I always still use the original logic symbols for gates and counters and latches and inverters and so on. I find the new style 'blocky' symbols need too much looking at, and taking into consideration of additional writing and symbols within the block. I always thought that the original symbols were all sufficiently different for the most part, to allow instant understanding of function by quick glance alone. I would agree that appliance schematics are often unclear, and use odd symbols. Also, with apologies to Herr Willberg, I think that German schematics from 20 or 30 years back, are some of the worst to follow that I've ever seen. I defy anyone who's not German, to follow a Grundig schematic, for instance ... Although Dutch, some of Philips' ones from a few years back were also a nightmare to follow. They had a very frustrating convention regarding where signals went when they (frequently) disappeared off the side of a page, and the signal was often nigh on impossible to ever find again ... But the prize for impossible to follow schematics, has to go to the automotive industry. Those diagrams have a convention all of their own, and always have done. Some of the most frustrating fault-tracing sessions of my life, have involved cars and the electrical diagrams for them. They are a cross between a schematic and a wiring diagram, with symbols peculiar to and only understood by automotive manufacturing initiates. Every bullet and connector is shown, using a variety of different conventions between manufacturers. Schematics go across multiple pages, with wires that leave often almost impossible to re-find on the next diagram. Colours, wire gauges and goodness only knows what other info, are all crammed onto the diagrams. Nightmare ... Arfa |