Get your schematic on
Humanoido
Posts: 5,770
Exactly what is going on with the diverse and totally mixed up schematic versions with absolutely no symbol standards being followed?
It seems like everyone has their own standard. In particular, I see 3.1 volts or 5 volts being shown as a triangle. Ground is usually the three progressively smaller lines. But not! On many schematics, I see voltage at a small perpendicular line termination, or a zig zag line, or ground is a triangle or an arrow (lots of arrows for lots of things).
In one schematic, the +5v and ground are large and small triangles (but they spell it out as gnd and +5v so don't pass out yet). Unbelievable if you mix up hot and ground.
Sometimes there is a text explanation but most times not. For years, we had an iconic standard that we followed. What happened suddenly?
One reason may be the many diverse schematic programs, each with varying symbol sets. Some have limited icons and sometimes we must draw our own. In one drawing program for example, there is no LED symbol. But c'mon, it can't be too difficult to draw three parallel lines for a simple ground symbol.
Maybe we should post and establish a Schematic Standard? Guys, it's the year 2010 and time to get your schematic on.
humanoido
images.google.com/images?hl=en&q=schematic&um=1&ie=UTF-8&ei=ANKsS-3iCZHm7AO6gtS3Dw&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CCAQsAQwAw
www.parallax.com/Portals/0/Downloads/docs/prod/compshop/27804-AbsBinRotaryEndcoder-v1.1.pdf
It seems like everyone has their own standard. In particular, I see 3.1 volts or 5 volts being shown as a triangle. Ground is usually the three progressively smaller lines. But not! On many schematics, I see voltage at a small perpendicular line termination, or a zig zag line, or ground is a triangle or an arrow (lots of arrows for lots of things).
In one schematic, the +5v and ground are large and small triangles (but they spell it out as gnd and +5v so don't pass out yet). Unbelievable if you mix up hot and ground.
Sometimes there is a text explanation but most times not. For years, we had an iconic standard that we followed. What happened suddenly?
One reason may be the many diverse schematic programs, each with varying symbol sets. Some have limited icons and sometimes we must draw our own. In one drawing program for example, there is no LED symbol. But c'mon, it can't be too difficult to draw three parallel lines for a simple ground symbol.
Maybe we should post and establish a Schematic Standard? Guys, it's the year 2010 and time to get your schematic on.
humanoido
images.google.com/images?hl=en&q=schematic&um=1&ie=UTF-8&ei=ANKsS-3iCZHm7AO6gtS3Dw&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CCAQsAQwAw
www.parallax.com/Portals/0/Downloads/docs/prod/compshop/27804-AbsBinRotaryEndcoder-v1.1.pdf
Comments
www.leonheller.com/Propeller/XProp/XProp_sch.pdf
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Leon Heller
Amateur radio callsign: G1HSM
-Phil
An example of this would be using a rectangle for a resistor, with the resistance value inside the rectangle. With older production, re-production, transmission (or lack thereof) technology, the value would be hard to read, or the rectangle would need to be excessivley large. With current technology (no amperage pun intended), the rectangle and value are very legible, and take up less space than the "zig-zag" and value near by. There is also less possibility of reading the wrong value on adjacent resistors.
As the world completes the transition to surface mount technology, there are also probably changes triggered, not only because the shape and "size" designation changes (no colored strips on SMT resistors), but also the technology of how the individual components is changing, and older symbols don't necessarily have the same meaning to the "new generation" (does a bent piece of wire really represent a resistor anymore?).
In terms of "Ground" and "Power", with more circuits dealing with multiple voltages, and even requiring negative voltages, or using "differential voltages" not sharing "ground", the differentiation of "ground" may not be as meaningful as it once was (I did say "may not"...).
Also, what "standard" means varys by country/industry/location. An "electrical" schematic may look very different than an "electronic" schematic, and European "standards" are different that American. As we become more "global", we see more variations.
Yes, it would be nice if we all had the same set of universal symbols, but that has not happened, and probalby won't, if for no other reason than someone will think (at least to them) that they have a better way. I'm sure ANSI, IEEE, ISO, SAE, etc. have "standards", but would suggest that they probably have several options, and/or industry is going to be taking liberties.
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John R.
Click here to see my Nomad Build Log
I feel it comes with time .
To me this is a fun challenge . Makes me think more
Peter KG6LSE
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"Carpe Ducktum" "seize the tape!!"
peterthethinker.com/tesla/Venom/Venom.html
Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. —Tanenbaum, Andrew S.
LOL
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···································Fix it, if ain't broke!
D Rat
Dave Ratcliff N6YEE
Looks pretty good too!
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Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
If not, I bet erco could find a commercial one on sale for 49 cents
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Leon Heller
Amateur radio callsign: G1HSM
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John R.
Click here to see my Nomad Build Log
The standard components in Protel are so "standard" and bulky as well but my philosophy is make it simple and clear. All those old style black and white symbols are fine for hand drafted symbols before CAD, I personally never feel compelled to follow tradition and reinforce inferior and redundant ways of doing things.
Take this little circuit here, it is a Propeller USB interface with a little PIC processor to multiplex all the handshake signals, handle Propeller reset timing, and run some extra LEDs, all on the I2C bus. Anyway, notice that I like to color my LEDs, novel isn't it, seeing that they aren't filament bulbs I think it is appropriate and besides the symbol matches a footprint which although they may look the same it ensures the designators and/or BOM specifies the color.
I find when it comes to circuit values that the schematic becomes cluttered with values and then the symbols have to be spaced to allow for the values. By "choosing" to use rectangles for resistors I can at least place the value inside the rectangle which is not possible if you use the old zigzag symbol. Also with capacitors it is ok to have parallel plates but I don't bother with the old polarized curved plate method I just color code the plate as red for positive in case they are polarized. Then rather than trying to use all the multiple units of capacitance it becomes easier to code them in the pico-farad + multiplier code so that 10uF becomes 106 = 10 x 10^6pf. A 0.1uf becomes 104 which is how the case is marked by the way and also means that the troublesome decimal point is done away with. Also with resnets the physical orientation is important or handy to know so I use a bar so that on the schematic you can see how it would relate to the pcb. With resnets too I find that many schematics have a single component for the resnet so that a smd 4 resistor pack is shown as 4 resistors in one component. This leads to a schematic that is no longer easy to read becoming more like a wiring diagram especially if those resistors are not all joined in the "traditional" way.
The main point is that I can read the circuit clearly and how it is handled by the CAD package as well so there is no confusion. If I can glance at it and see the circuit flow then that makes it easier for others also. I also pretty much netlist everything so it makes it so much easier to trace the pcb in case of sensitive pathways or just plain optimizing. All my datasheets too are oriented in landscape mode which does away with twisting your head to view schematics or having mixed orientations plus all monitor screens are landscape mode anyway and nothing prevents us from printing in this mode.
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*Peter*
And what's FB?
Not really, but given the date, I couldn't help myself.
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John R.
Click here to see my Nomad Build Log
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Chris Savage
Parallax Engineering
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While I can, have, and occasionally do, work in non-Micro$oft environments, and while M$·would probably not my preferred environment, it's what I get to deal with at the "day job", and I really don't want to get into the intracacies of another set of libraries at the level that would be required for·a project like this.
I also question, given the available options already out there, if the effort would be worthwhile.
Back a number of years, I started working on graphic software for model railroad layouts and control panels.· The concept of keeping things "connected" as they are moved especially if you need to keep things tangent to arcs, etc., is non-trivial.· Fortunately for my sanity, I discovered robotics, and have set the railroad stuff aside.
Then after the schematic, routing the PC board gets into a whole 'nother set of opportunities, even without trying to "auto route".
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John R.
Click here to see my Nomad Build Log
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John R.
Click here to see my Nomad Build Log
http://forums.parallax.com/attachment.php?attachmentid=68091
or here
http://forums.parallax.com/attachment.php?attachmentid=68292
humanoido
Post Edited (humanoido) : 4/1/2010 9:42:11 PM GMT
I mentioned in my post that I mark individual resistors in an array (resnet) with a polarity symbol which happens to be a line or it could be a dot for the reasons that I had mentioned. Why would anyone think that in a schematic (not pcb) that would be a diode symbol?
Here is part of a schematic with resnets and a diode.
As for that other mention of "thin" schematic lines well what do you expect from a screenshot, that's certainly not how they reproduce in a pdf or even a png embedded into a document.
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*Peter*
Post Edited (Peter Jakacki) : 4/3/2010 5:00:46 AM GMT
The schematic vs. pcb question is interesting though. Some of the conventions you use are based on the physical appearance of the components. You're using capacitor codes*—how the case is marked—rather than actual values. Your resistor symbol indicates orientation of resnets.
Nothing wrong with that, but you can't then roll your eyes when someone wonders why you wouldn't use a diode symbol that looks like a diode.
(* Thanks for the explanation of pF + power-of-10, btw.)
You mention symbols based upon physical appearance but the rectangles are not meant to convey anything other than a 2-terminal component, be it a resistor or inductor plus space inside to insert the value. That's also why the diodes are encapsulated in the same rectangle but clearly a diode. The capacitors I would like to make rectangles too but by preserving the instantly recognizable parallel plates and simply spacing them apart a bit further I can insert my value in between much like the rectangles.
This is part of my rationale and it's certainly not fixed but I am always looking at ways to improve the appearance of schematics while preserving some measure of convention which is of course necessary, to a degree.
BTW, congratulations on 3rd place, well done! I reckon if the contest was divided into a hardware and a software section you would have won 1st place for software hands down.
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*Peter*