Schematics & standards
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From: Cydrome Leader on 19 Jun 2010 23:57 Arfa Daily <arfa.daily(a)ntlworld.com> wrote: > > > "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 ha, plus every damn wire is taped together into some completely awful harness. There has to be at least 50 pounds of PVC electrical tape in every car out there.
From: Adrian Tuddenham on 20 Jun 2010 04:16 Arfa Daily <arfa.daily(a)ntlworld.com> wrote: > "David Nebenzahl" <nobody(a)but.us.chickens> wrote in message > news:4c1d00fe$0$2388$822641b3(a)news.adtechcomputers.com... > > On 6/19/2010 8:35 AM Adrian Tuddenham spake thus: > > > >> David Nebenzahl <nobody(a)but.us.chickens> wrote: > >> > >>> Someone else made a comment in another thread here about weird > >>> schematics (like for home appliances). > >>> > >> [...] > >>>... 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. > >> > >> I find the 'gap' convention is easy to draw (with a computer) and > >> extremely easy to read. It also looks tidy. Four-way junctions which > >> could be mistaken for crossings should never be used, they should be > >> staggered instead. > >> > >> e.g. > >> http://www.poppyrecords.co.uk/compton/images/BassAmplifier.gif > > > > BZZZZZZT! Fail. > > > > While the gap thing looks OK for non-crossing wires, I have to ding the > > drafts-person of that schematic for the following: > > > > o Idiosyncratic symbols for electrolytic cazapitors[1] > > o Idiosyncratic ground symbol (one horizontal line????) > > o And no, I disagree about those offsets for connecting wires. > > > > That's totally unnecessary here: it would be quite obvious that all those > > vertical wires connect to what is obviously a bus or rail. A well-drawn > > dot is all that's needed there. > > > > (And I don't much like their transistor symbols either) > > > > > > [1] With apologies to J. Liebermann. > > > > I must say that I don't really like the staggered connections,... They do tend to give a slightly messy appearance, but the alternatives were worse: 1) Stagger one half of the output stage slightly to the right (takes up more space and doesn't shout "symmetry" to the reader). 2) Use loops for crossings (even messier in appearance). 3) Dotted and un-dotted crossings (error-prone because the straight-through line misleads the eye in spite of the dot). -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
From: Arfa Daily on 20 Jun 2010 05:12 "Cydrome Leader" <presence(a)MUNGEpanix.com> wrote in message news:hvk3bu$3ju$1(a)reader1.panix.com... > David Nebenzahl <nobody(a)but.us.chickens> wrote: >> 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 > > I find rectangles obnoxious, unless somebody from europe is drawing > something in front of me. > >> 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. > > I was taught the half-loop shape first, then moved to the dots and no > dots. It seemed like how you're taught to ties shoes in a really complex > method of making two rabbit ears first, then tying them. > >> 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? > > I first saw that on this newsgroup. My question is what idiots came up > with it and why? Can you really not understand it ? Or are you being deliberately obtuse ? It has now been explained to the point where a child could understand it. I think it was actually me who you first saw using it here, and I'm pretty sure that we went through it all for your benefit at the time ... Arfa
From: Dave Plowman (News) on 20 Jun 2010 05:29 In article <hvk3bu$3ju$1(a)reader1.panix.com>, Cydrome Leader <presence(a)MUNGEpanix.com> wrote: > > 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? > I first saw that on this newsgroup. My question is what idiots came up > with it and why? It's been around on this side of the pond for many a year. It uses fewer characters and no chance of not seeing that little full stop in a poorly copied diagram. Like everything else you need to get used to it, though. -- *If you're not part of the solution, you're part of the precipitate * Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: Bruce Esquibel on 20 Jun 2010 09:30
Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > They certainly look strange when you have been used to the > point-contact symbol, but you must admit they give a clear > representation of a junction transistor. No they don't. You guys talk about faded photocopies and the usage of 2.2K vs. 2K2, it ever occur to you a faded photocopy of the BassAmplifier2.gif, those transistors come out looking like diodes? I'm with Dave, I never seen that either. Plus, what the hell is the S-N-U on the tip35c's and R-G-O on the tip36'c? I can't find a single datasheet for them that uses anything else besides E-B-C. That diagram is terrible. -bruce bje(a)ripco.com |