Schematic preferences
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From: krw on 18 Jan 2010 21:16 On Mon, 18 Jan 2010 19:21:33 -0600, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:u0v9l5lk6k4tqlfrpef1b85msqju2trcd0(a)4ax.com... >> PNP emitters up, NPN emitters down! > >Ah, but Tek doesn't do that -- IIRC (and maybe I don't), they often drew >balanced circuits symmetrically, like so; >http://webpages.charter.net/dawill/Images/Deflection%20Amp.gif > >The side-by-side approach is more common outside of oscilloscopes, but does >lead to messier drawings because you're showing everything twice: >http://webpages.charter.net/dawill/Images/Tube%20Oscilloscope%20Vertical.gif >That, and the sheer number of passives indicated, is why this simple >balanced amplifier is 1133 pixels wide. I like diff-amps with the components side by side, mirrored left and right. +V at the top, -V at the bottom.
From: Jon Kirwan on 18 Jan 2010 21:21 Just by way of example, here's a poorly laid out circuit: http://www.swtpc.com/mholley/PopularElectronics/Nov1967/PE_Nov_1967_pg30.jpg In my opinion. Find the +rail and ground lines and trace them around the schematic. What's the point in the busing everywhere? How much do those 'wires' interfere with following function? Now, if you are point-to-point wiring stuff you might lay out things and then run the heavy wire around like that, soldering to it along the way, I suppose. Maybe. But if you are trying to follow the operation with understanding there are better ways to draw it. It's not the worst example around. But it addresses some of the points. Emitters from different PNP's pointing differently. Emitters from NPN and PNP pointing the same way. Bus wires trapsing around all over the place almost looking as though they might carry signal. Etc. Jon
From: MooseFET on 18 Jan 2010 21:39 On Jan 18, 12:37 pm, D Yuniskis <not.going.to...(a)seen.com> wrote: > Hi, > > Of course, this is *highly* subjective -- but, I'd enjoy hearing > folks' "conventions" used when preparing schematics (that *others* The way I do it: I draw on size B and reduce to a size A so that an 8.5x11 printer can print it. Unless there is a darn good reason, all op-amps have their out puts to the right. The "darn good reason" may be that it is in the feedback path. The power supplies are always named as a voltage not just Vcc All parts have the power pins shown. The + is usually on the top. The exception is references and regulators where it is on the left. Signal names are always somewhat meaningful and never something like "SCATCB" as I have actually seen. In general the connections to a sub block are shown with the inputs on the left and output on the right. Exceptions are made for feedback signals. I never crossed lines as a connection point. If two lines connect to another line, they are offset. PNP transistors are drawn with the emitter up. Bypass capacitors are shown on the sheet with the parts they are near The triangle ground symbol means the circuit ground of the PCB. The three line symbol means the connection to the chassis. The one like this: ! ----------- / / / / means planet earth Mounting holes are shown if they have electrical meaning. Notes go in the lower left corner of the sheet. The reference of a part encodes the page it is on. R307 is on page 3
From: John Larkin on 18 Jan 2010 21:53 On Mon, 18 Jan 2010 19:37:23 -0600, krw <krw(a)att.bizzzzzzzzzzz> wrote: >On Mon, 18 Jan 2010 19:10:51 -0600, John Fields ><jfields(a)austininstruments.com> wrote: > >>On Mon, 18 Jan 2010 16:13:23 -0800, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >> >>>We use big (75 mils in PADS) dots. There's nothing wrong with a 4-way >>>connection if the dots are obvious. >> >>--- >>If one knows what's happening at that junction, that's fine, but it's >>happened more than once that a drafting droid saw two lines crossing and >>figured they should be connected. > >When was the last time you saw a drafting droid? ;-) All my engineers (excepting me!) CAD their own schematics. I still draw with pencil on vellum and let The Brat enter them for me. But I check them very, very hard. John
From: John Larkin on 18 Jan 2010 22:02
On Mon, 18 Jan 2010 18:39:06 -0800 (PST), MooseFET <kensmith(a)rahul.net> wrote: >The reference of a part encodes the page it is on. R307 is on page 3 Yikes! Production would lynch us. After the layout is done, we resequence the reference designators in physical and numeric order and back-annotate the schematic. John |