Schematics & standards
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From: Adrian Tuddenham on 20 Jun 2010 10:06 Bruce Esquibel <bje(a)ripco.com> wrote: > 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? Perhaps, but there aren't many diodes with three wire connections that they could be mistaken for. The direction of the arrows might be lost if they became blobby, but so would the arrows on the point-contact symbol. > I'm with Dave, I never seen that either. It is unusual nowadays, but if you had been designing in the 1960s you would have come across it from time to time. > Plus, what the hell is the S-N-U on the tip35c's and R-G-O on the tip36'c? Slate-Brown-Blue. Red-Green-Orange. It is the colour code of the wires. The output transistors are mounted on individual heat sinks and connected to the rest of the amplifier by a wiring loom, so the colour code is helpful for fault-finding. > I can't find a single datasheet for them that uses anything else besides > E-B-C. I didn't think there was any need for E-B-C as that should be obvious from the symbols. > That diagram is terrible. We were discussing our preferred symbols and that diagram illustrates my preferences. My personal dislikes are: 1) The crossing & dot convention. 2) Transistors and valves shown as a collection of electrodes floating in space without envelopes. 3) Power supply rails all mixed up with the earth rail at the bottom of the drawing. For an example of a truly horrible circuit diagram see: <http://www.audiosharing.com/archive/western/we_amp/pdf/No.8.pdf> When re-drawn it makes a lot more sense: < http://www.poppyrecords.co.uk/other/images/WE8a.gif> -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
From: Arfa Daily on 20 Jun 2010 11:59 "Adrian Tuddenham" <adrian(a)poppyrecords.invalid.invalid> wrote in message news:1jke3p0.aabxi6jodbawN%adrian(a)poppyrecords.invalid.invalid... > Bruce Esquibel <bje(a)ripco.com> wrote: > >> 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? > > Perhaps, but there aren't many diodes with three wire connections that > they could be mistaken for. The direction of the arrows might be lost > if they became blobby, but so would the arrows on the point-contact > symbol. > The symbol for an adjustable zener, used typically in switch mode power supplies, looks pretty similar :-) Arfa
From: whit3rd on 20 Jun 2010 12:31 On Jun 19, 3:29 pm, PlainBil...(a)yahoo.com wrote: > I prefer the 'old' style - zig-zag lines for resistors, parallel lines > for non-polar capacitors, etc. That's OK for digital work, but for RF or high Z, your capacitor symbol needs to have one line, one curve, as appropriate. Another subtlety: if the tube symbol has a dot, it's OK to see a plate glow. No dot, that glow means ... too much current.
From: Cydrome Leader on 20 Jun 2010 12:55 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, but what's > wrong with the transistor symbols ? And the single heavy horizontal line for > the 0v rail, is very common this side of the pond. 0v rails always used to > be shown as a heavy horizontal line right across the schematic, sometimes > with a chassis symbol attached as well. These days, most schematics are so > complex, that the 0v line is now left out, and 'abbreviated' to individual > short heavy lines at each connection point on the schematic. The > electrolytic symbol is not, however, the one commonly used here, which is a > pair of rectangles, one filled in for the -ve side, and the other open for > the +ve side. Sometimes, the American convention of one straight and one > curved plate, is used. > > Arfa > Americans also do crazy things like just write a + sign next to the anode if two parallel lines of equal size are used to represent a capacitor. On the other hand, only the cathode is marked on electrolytics for some reason. Is there a great story behind this?
From: Cydrome Leader on 20 Jun 2010 13:01
Arfa Daily <arfa.daily(a)ntlworld.com> wrote: > > > "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 > That's funny as writing out values the correct and conventional way doesn't need explanation and a child can follow it, and it's been that way for decades. I'm still waiting to see values for money being written out as 44"euro symbol"66 with cents after the end instead of 44.66. periods are too confusing, commas are too confusing! help, we're all stupid these days! |