Schematic layout - Page 1
Forum section: electronics / projects

author: PStevenson
author_rank: Regular Contributor
timestamp: January 17, 2012, 09:51:32 pm
content: I'm currently working on a design which I eventually want to opensource and my question is, looking at the posted schematic (it's not finished) what suggestions would you give to make the schematic look more "professional" you know, as easy as possible to read because at the moment I tend to do schematics just following signal path and I haven't got a clue whether I should be doing it a different way or not.

author: Psi
author_rank: Super Contributor
timestamp: January 17, 2012, 10:02:54 pm
content: Looks pretty nice, only things i can see are.- Add a title block with description, author name and any other details- Label each section and what it does.- Maybe change the color scheme so people can print it out without using a full page of toner/ink.(Note: i like black backgrounds. I find them much easier to read on the PC. But for printing you really want white.)Maybe include a version for each.You could also include any references, voltages of waveforms at key points on the circuit to show what normal operation should look like.That helps anyone building your circuit, as they can test a few points, compare the readings to the diagram and see where things start to go wrong on their circuit.

author: PStevenson
author_rank: Regular Contributor
timestamp: January 17, 2012, 10:42:21 pm
content: oh yeah, I will change it from black to white of course, that's just cause it's easier to work onand the details of course.labelling each section is a good idea as are the voltages, I rely so much on schematic voltages when I do repair workI can't believe I didn't think about that!

author: vk6zgo
author_rank: Super Contributor
timestamp: January 17, 2012, 11:18:20 pm
content: If you have sections of the overall circuit which connect together,either do so via a line,or indicateclearlywhat the connection is,as what seems self-explanatory to you,because you know the circuit "like the back of your hand",may be confusing to others.It is annoying when troubleshooting to have to hunt around to find where the signal is supposed to go.The worst thing is, that this is a quite common problem,which with a little forethought, would not exist.VK6ZGO

author: PStevenson
author_rank: Regular Contributor
timestamp: January 17, 2012, 11:45:46 pm
content: oh yeah, I will draw some form of interconnects which will be labelled, it's only this way at the moment because it's not fully tested, just the individual groups.but that's what this post is about, making sure I've got the bases covered so thanks for pointing these things out

author: Rufus
author_rank: Super Contributor
timestamp: January 18, 2012, 12:04:05 am
content: Cosmetically it is a bit of a mess but I assume you intend to tidy up all the overlapping text which will probably require you to spread things out a bit more.I assume the X things are pads, not a symbol that means anything to me.DON'T USE 4 WAY JUNCTIONS.VCC isn't a good name for an analog circuit +ve supply, V+ for a mid rail virtual ground is also confusing.You have a few circuit problems. You can't parallel op-amps. R6 doesn't do anything, IC3B doesn't do anything. Might be more if we knew what it is supposed to do.

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 12:16:59 am
content: I would also like to see a white background. Definitely, a schematic has to be printer friendly. Converting it to a black and white schematic is a good idea, as it will probably end up being printed in monochrome anyway. If the schematic editor doesn't easily allow for the schematic to be converted into a black and white schematic with a white background, it is very easy to do in any photo editor. The differentiation between the green tracks and the red component bodies is only needed within the schematic editor package so you can differentiate the two. For the end user, it is unneeded information.Most of the labels have to be moved to better positions. Rotate the ones that are vertically orientated, and try and avoid having labels on top of connections.If there is going to be a definite supply voltage for this circuit - like 12v, rename VCC to 12V. It is more informative.Use a different ground connection symbol to all other power connections - you want the ground to be visually obvious. Also a name like VCC/2 or 6V (if VCC = 12V) is more explanatory then V+. I prefer it if the direction of the connection to supplies is consistent. At the moment you have connections to V+ going up, down and horizontal. If you pick one orientation and stick to it, the circuit is easier to read.I prefer it if all components don't directly connect to junctions (like IC3D output, C25 and C26) or to other components without any green connecting trace. There is a missing junction near the output if IC7A.Definitely document functional sections on the schematic, like the IC3C, IC3D, IC4A, IC4B filter. Describe what the filter does or add a mini graph showing the filter response.Add extra text to describe inputs and outputs. So OUT+1 and OUT-1 could have some text saying "Headphone socket" or similar. Same with PAD2, PAD3, IN and OUT. For IN and OUT, it is a good idea if possible to show both wires of the input and output together. It may be obvious to you that the input is between IN and GND, but it may not be so obvious to someone else. After all, V+ is the signal common for all the opamps - perhaps the input is meant to be between IN and V+? Make it clear. Even if you provide a board layout, some people will be building your circuit from the schematic only.It is a good idea not to use up spare opamps, etc just because they are there. People viewing your circuit will assume everything has a reason.I know the schematic is not complete, but at the moment IC3a and IC3B are two unity gain amps is series, connected via an unnecessary C8, R6 and R7 and that makes it puzzling. If there is a subtle reason for some parts that is not obvious, some text on the schematic to explain the reason is great. Otherwise keep the circuit as simple and as clean as possible. If there are left over opamps, it is much better to leave them unused, then to get them to do an unnecessary task.I am particularly worried by the paralleled opamps (IC7). Opamps are just not designed to work like that. It may appear to work, but the reality is the two opamps will probably be permanently in current limit as they fight each other. Definitely will waste power for no benefit at all. A single opamp will perform better then two in parallel.Richard

author: PStevenson
author_rank: Regular Contributor
timestamp: January 18, 2012, 12:43:36 am
content: thanks for the advice, the op-amp parts that have a bit of concern surrounding them are part of a harmonic distortion effect, one side boosts high frequency harmonic distortion and the other low frequency, it's quite a nice circuit but it does not leave a clean circuit, basically it's part of a guitar amplifier for a very niche genre of music that requires that particular sound (Djent)the circuit "modules" have been tested so I know those work, there are other parts that aren't there yet which is why there are little blank areas,the parallel op-amps was an oversight, I was trying to decide which package to use and I thought I would put facility to use one or the other on the PCB so that won't be an issue at the end design.I'll work on eliminating the 4 way junctions, and I will definitely change it from black to white once it's done, I do like to have a printout myself when I finish these things and I will "smash" the component names and make sure they are better readable.all the ins and outs will eventually be in one chain.I should have really explained better thinking about it now! but as you say, when you know something like the back of your hand, it's easy to forget that everyone else doesn't

author: vk6zgo
author_rank: Super Contributor
timestamp: January 18, 2012, 04:12:49 am
content: Don't beat yourself up about the "know it like the back of your hand" stuff,it is pretty much endemic among Electronics manufacturers(especially European ones),to assume the person trying to use the schematic is psychic!Most Techs & Engineers are "Psycho",but that's a different thing!Just a niggle,but IC3a & IC3b are incascadenot in series,Richard.Series implies a kind of circuit which was used with discrete components,known as "Cascode".VK6ZGO

author: gxti
author_rank: Frequent Contributor
timestamp: January 18, 2012, 04:47:11 am
content: I'm definitely guilty of over(ab)using net labels to connect things together, especially near microcontrollers. Makes blocks much easier to manipulate, but harder to spot where things are connected.On a technical note: export schematics as PNG, not JPG -- it preserves line drawings etc. much better than JPG. Note the fuzziness and smeared color, especially around curved lines. Often PNG files will be smaller, too. Rule of thumb is to use JPG for photographic data, and PNG for drawings and other generated images.

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 05:04:28 am
content: Quote from: vk6zgo on January 18, 2012, 04:12:49 amThat may be right, but who even uses the word "Cascade" nowadays? Oops - I just did.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 18, 2012, 06:40:50 am
content: Quote from: amspire on January 18, 2012, 05:04:28 amI would suggest that most Electronics textbooks do,for a start.The point is,that they refer to two totally different concepts,so if we are supposed to be Electronics people we should use the appropriate terminology.Actually "Cascade" beer is quite nice!VK6ZGO