Why do my inverted connectors resize?

New to KiCad.
I created a symbol which has some inverted output signals:

But when I insert this symbol into my schematic, the circles get resized. Why is this/what am I doing wrong?

The general schematic-setup parameter “Pin symbol size” affects this presentation. It allows to globally change the appearance of a schematic according to the users viewing-liking.

File–>Schematic Setup–>General–>Formatting–>Symbols–>pin symbol size. Change to a smaller value. I think the picture from your symbol-editor equals around 10…12mil.

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More like 50 mil.

The default is 25 mil.

Ah. I see. The mils confuse the hell out of me. I’m trying to convert to mm and make everything follow ISO standards but I am beginning to see this will probably not work out as I want.
Thanks for the help.

The problem is the whole schematic system revolves around arbitrary increments someone decided to call mils. They could just as easily be called “peanuts”. They are not measurements as such, more like ratios.

Measurements in Schematic are pretty much meaningless as the file is printed to fit the sheet of paper.
Schematics are just an abstract, hopefully easy to follow, view of the PC assembly.

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I get that now. Which is a shame really. It means having to make and maintain 2 circuit diagrams. I understand KiCad isn’t made for professional use but even as a hobbyist I like to document my projects properly. Its part of the fun. So be it. There are worse things in life.

Is the 7406 for practice or are you really going to use one? There is already a 7406 symbol in the library, but with 7 units (6 inverters, usual triangle with inverting output + 1 power unit) which may make your schematic easier to read as you do not have to route the wires to a single rectangle that’s your symbol above.

It was both for practice and use. Like I said: I wanted an IEC/ISO compliant circuit diagram. Using parts isn’t :wink:

What ISO standard tells that symbols must be defined in millimeters? Why do you have to make 2 circuit diagrams? What does this have to do with documenting projects properly?

BTW, KiCad is made for professionals – it’s the vision of the project, even though it can’t still fully compete with some of the more expensive commercial software. If you can tell what’s the actual problem here which should be fixed for KiCad to be suitable for professionals, please tell.


The standards that deal with technical drawings. They define line thickness, text height and symbol-sizes etc. E.g. iec60617 but there are others.

I’m sorry to say this but, You’re Wrong. Mil’shave been a standard used in engineering and drafting for over 100 yrs… One ‘Mil’ - 1/1000 inch. I grew up using Mil’s and confusion is not too different from listening to smart people on the New’s shows use the word “Preliminary” but, pronounce it, “Puliminary”. That’s not a real word, is it

This, The introduction of the thousandth of an inch as a base unit in engineering and machining is generally attributed to Joseph Whitworth[12] who wrote in 1857


ADDED: Take a look a the Gerber Specification, you’ll see (example)


I think jmk does know what mil (also called thou) means.

In the schematic the units are not important, the size of the lines does not mandatorily need to be mils, mm or peanuts. Just some length unit.

I grew up using mm. When I first time used PCB design software (about 1989) I first time heard about mils.

This is true only if you regard the schematic as just an intermediate to make a pcb. But if you want the schematic itself to conform to industry standards then it does matter. And yes, I understand that KiCad is not e.g AutoCad and not intended for that use. I am not criticizing or complaining. I was just confused and baffled by the choice to not follow international standards.

I have been a technical draftsman for 10 years in the past (30+) years ago for an engineering firm. Drawings need to adhere to both international, national and company standards. The way you use symbols, which symbols, text placement, line thickness, etc. Obviously KiCad is not intended for making such drawings but for making pcb’s. But this means you now have 2 circuit diagrams: one official one and one used to create a pcb and they use different drawing styles and symbols. This is a maintainers nightmare and adds to costs, not to mention the potential for mistakes and confusion.
I have no idea how to solve that but at the very least there should be some type of import/export to dxf where measurements do not get messed up.

The mils is pretty much legacy and the library of parts has developed with them. That is the main issue. One world, one measurement system? That would be nice but it isn’t reality. A schematic is not to scale so I really don’t see how measurements are ‘standard’ except in how the symbols relate to one another.

Still. It’s a matter of, if Kicad doesn’t currently meet you needs, check back later but most just work with it. Personally though, I’ve never dragged out a ruler and started measuring things on a schematic, but, that’s me.

Lol. Drawing standards are for consistency, maintainability and readability. And sofar I very much like KiCad for its intended use. I just struggle with how to integrate it into my workflow as it is pretty much isolated from other software. It was not my intent to criticize or complain or start a discussion.

As far as i have read 60617, it allows to resize and/or scale but it states that the line width should stay the same (I don’t know what that width would be…). I think the document about those things was 11714 that now changed to 81714.

On the KiCad’s side, grid points can be changed, and symbols can be designed as required. This is not a limitation, this is just the lack of those kind of symbols in the official libraries.

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Yeah it does. But it also relates to (if I’m not mistaken) ISO 128. The symbol sizes relate to the text size of their labels. So the resizing is limited to e.g. 2.5 or 3.5 mm text variations. And it needs to be consistent across the sheet. All symbols also relate to each other as 60617 defines them to a common grid.

Drawings have revision control, are signed by Drafter, Engr and Mgm’t

The companies and gov’t I’ve worked for had a Documentation Dept, wherein engineers/drafter turned in the working drawing/schematic and someone-else made them into official doc’s for signature and release and control.

For small companies with a more ‘informal’ system, well… depends on what you want, where you work and the “Client’s” requirements.

There are Resources for gaining an understanding of this…

There are ‘Standards’ (those we often see, such as ANSI…etc) and many resource-aids that filter the standards into a more specific, useful pamphlet…

Example screenshot (I can’t locate my Electronics guide)