Thank you all for the answer on changing pin number locations. I've tried to learn several of the PCB CAD programs and none ever said this in their tutorials. I know that any of you that help me in my threads think that I care to learn, but I really do. It's just very hard when doing it by yourself with no "hands on" help. No one in my circle even cares to do this stuff. Most books are written to be used in a class room with a teacher to expand on the content and answer questions when they come up. Or they are written for people that already have a certain level of knowledge. No one is born with this knowledge and many that have it and used it forget what it was like for them in the beginning.

 

@shortbus

Since you're just starting out, you shouldn't be too concerned about rules, guidelines, conventions; and definitely don't let them stop you from learning something new. I've known people who were very sloppy with their work, but you can't argue if it works.

There's an artistic aspect to drawing schematics and some are more anal about it than others. I personally will spend hours reviewing my schematics to make sure they're understandable, at least to me, and neat. Anyone who has done this professionally should show some pride in workmanship. Amateurs are not held to the same standards.

As others have commented, schematics are a form of communication; it doesn't need to be perfect, just good enough...

 

The convention I was taught was positive exponents were uppercase and negative exponents were lowercase, so 'M' would always be Mega and 'm' would always be milli.

That's true in most cases, however 'k' is used for 10^3 because 'K' is the unit for Kelvins. Of course, 'm' is 10^-3 and 'm' is also the unit for meters, but since there are two M/m prefixes it's not possible to disambiguate them. In fact, the prefixes below 10^3 are all lower case, but those for 10^2 and 10^1 are seldom used (except for hectares and perhaps a few other specialized units of measure).

If I had been part of the process, I would have devices prefix multipliers that that went alphabetically and such that the uppercase and lowercase versions were reciprocals. Imagine how many fewer mistakes would be made if A=10^3, B=10^6, C=10^9, ... and a=10^3, b=10^6, c=10^-9, ....

 

Engineering is about problem solving and problem solving is about communication.

And communication is about clear structure and carefully chosen words... IMHO

 

I seldom do schematics, since practically all of my circuits are for personal use... and I commit the sin of drawing the PCB directly and then assemble it... 90% of the time it works on the first try... but then after the years go by, I find it hard to read and interpret what I drew...
It's just like code. Code has to be thoroughly commented and explained, and supported by previous flow chart work. The function of schematics is the same, on a graphic scale.

My only objection to the normal conventions would probably be:

Dots connect, crosses don't

I'd rather draw the dots and delete the side of the traces where crosses happen, just like in this schematic:



I think that drawing crossing paths that way makes it even clearer.

Speaking of which... I'm not sure if this schematic meets all the standards you've just mentioned!

 

I seldom do schematics, since practically all of my circuits are for personal use... and I commit the sin of drawing the PCB directly and then assemble it... 90% of the time it works on the first try... but then after the years go by, I find it hard to read and interpret what I drew...
It's just like code. Code has to be thoroughly commented and explained, and supported by previous flow chart work. The function of schematics is the same, on a graphic scale.

My only objection to the normal conventions would probably be:


I'd rather draw the dots and delete the side of the traces where crosses happen, just like in this schematic:

View attachment 86993

I think that drawing crossing paths that way makes it even clearer.

Speaking of which... I'm not sure if this schematic meets all the standards you've just mentioned!

The blank space surrounding a wire in a schematic is really not a good way to do it, IMHO. In crowded schematics it makes it much more difficult to follow, and can even be misleading at times. I really don't recommend doing that.

At 4-way junctions I prefer to offset two of the lines to prevent four wires coming into one dot. For example:



is not a good way to represent a junction. Depending on your software, that dot can be too small for some people to see, or it might wear off if you print it out, or the contrast when you print it out could make it disappear altogether. Instead I prefer to offset two of the wires like this:



That way there is no doubt whether or not there is a junction.

My only real complaint about your schematic (besides the white space where wires cross--again, I really don't care for that idea, and as someone who designs circuits for a living it actually makes me cringe ) is the chip. The ICL7660 is depicted more in a wiring diagram sort of way, and through experience I have learned that mixing wiring diagrams and schematics is not very good. It isn't so much a problem in this schematic, but in a lot I have seen it leads to very sloppy schematics that are difficult to read.

For example, this:

is much easier to read and follow than this:

 

the white space where wires cross--again, I really don't care for that idea, and as someone who designs circuits for a living it actually makes me cringe

Boy, am I glad I posted one of my most recent schematics... if you considered this one to be cringe-worthy , then my early ones would've probably induced projectile vomiting!

 

My whole objection to letting a cross of wires connect by putting a dot there is what happens if the dot doesn't print? True, that is more of a concern from the days of pencil on velum to a true blue print copy (smell that amonia!) but even laser jets have bad days.

Only allowing connections at T intersections removes any chance of error.

In cmartinez's drawing had the ground symbol been shifted over the cross connect would have been elimated. I also would put "Gnd Out" on the right side below the "Out" to better the flow: first few times looking I missed that output!

 

The objection I have to the "erase one wire as it crosses another" approach is that there's no way to do it (that I know of) and maintain a valid CAD schematic that lets you netlist the result. If you are just drawing pretty pictures, that's a different story, of course.

 

The objection I have to the "erase one wire as it crosses another" approach is that there's no way to do it (that I know of) and maintain a valid CAD schematic that lets you netlist the result. If you are just drawing pretty pictures, that's a different story, of course.

Hey! MY pictures are always pretty...

 

My whole objection to letting a cross of wires connect by putting a dot there is what happens if the dot doesn't print? True, that is more of a concern from the days of pencil on velum to a true blue print copy (smell that amonia!) but even laser jets have bad days.

Only allowing connections at T intersections removes any chance of error.

I agree 100%, which is why I posted the first two images in my last response

 

What about neatly hand drawn schematics? Drawn using standard symbols but not with a CAD program. Had a few tell me they wouldn't look at them if hand drawn. To me hand drawn was around before CAD, but what is the difference? By hand is easier for me.

 

I think hand-drawn schematics are completely acceptable for many purposes. I wouldn't include them in final documentation, but for communicating things during development they are perfectly fine. And for hobbyist stuff they are perfectly reasonable from top to bottom. If I were selling something I would do the final schematics via computer, but if I were posting stuff online for free use, I wouldn't blink an eye at the notion of scanning in a neatly hand-drawn schematic.

 

Engineering is about problem solving and problem solving is about communication.

there are professions where sloppy writing seem to be a must...

 

there are professions where sloppy writing seem to be a must...

I think that must include "college student" anymore.

 

well sure, but I was thinking of professionals (doctors, lawyers...)

 

well sure, but I was thinking of professionals (doctors, lawyers...)

I've got a friend that has been a graduate student here, nonstop, since 1994. I think that qualifies as "professional student"!

 

... I wouldn't blink an eye at the notion of scanning in a neatly hand-drawn schematic.

Except, of course, if that schematic was drawn by Mr Forrest Mims...

 

I think hand-drawn schematics are completely acceptable for many purposes. I wouldn't include them in final documentation, but for communicating things during development they are perfectly fine. And for hobbyist stuff they are perfectly reasonable from top to bottom. If I were selling something I would do the final schematics via computer, but if I were posting stuff online for free use, I wouldn't blink an eye at the notion of scanning in a neatly hand-drawn schematic.

You hit the nail on the head WBahn

 

If I were selling something I would do the final schematics via computer

Well I'll be... sorry about that WBahn, I misquoted your post in my last reply. It's this last phrase that I was referring to when I brought up Mr Mims.