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Proper? way of drawing circuit diagarams

This topic has probably been hot for as long as conscious circuit design has been exsistent. I personally have had various discussions with colleagues and friends, and I have been changing my opinion about circuit drawings for a number of times throughout the past ten years. Randomly browsing online, I stumbled upon this:

IEC-61082-1 INTERNATIONAL STANDARD - Preparation of documents used in electrotechnology

Such a wonderful useless document, which also costs 310 CHF which today is equivalent of ~254 EUR, whaaaat? I admit probably the 310 CHF is the fact that makes it totally useless. This is a document which is supposed to be a primer, an example of how one should document circuit designs, so that the latter are readable by others. I assimilate this document as e.g. an English-English or any other language dictionary, how can you learn and follow one language, when you have closed resources?

If we disregard my anger that this rag costs a fortune, let's have a brief look at it, or at least focus only on how in accodrance to IEC-61082-1 one should draw nets and junctions. Luckily someone has uploaded a 2002 draft version of this document in the semi-disgustingly-pirate website Sribrbrbrrdddd.

Let's zoom into the junction and wire crossing problem, which probably forms the "prettiness" of a circuit. Or at least if one follows one junction and wire crossing rule in his schematics "everything" tends to go well.

Excerpt from IEC-61081-1 (draft version 2002), source:Scribd

Reading further in the document we see that wire crossings sould be done at 90 degree angle and the hopping-over style according to this standard is considered as wrong. In many aspects I can see why it is considered as a bad practice, as if one has many wire crossings the hopping-over style tends to mess-up the diagram. Just a guess about where the hopping-over style comes from is that (maybe) back in the old days when one had to use pens (possibly fountain too) and ink, it is kind of easy to draw a joint unintentionally just by slowing down when drawing you line, or in general shaking your hand, you get what I mean. So, based on the 61081-1 draft here's a summary of the junction and wire crossings:

A simplified summary of the 61081-1 year 2002 standard in terms of junctions and wire crossings

In practice - so far I have seen an infinite number of tastes when it comes to schematic diagrams. Probably the most important rule to have in mind is not really following the standards, but to be consistent in how you draw. If we disregard junctions and wires, there come the symbols, and these may vary a lot with EDA tools and various foundry PDKs. E.g. how come the bulk of a mosfet should go out in the middle of the "transistor channel" and there should be no drain/source markings whatsoever. There IS a difference between drains and sources, that's why people have given them different names!

And at last, the famous "in accordance with standard" circuit diagram from xkcd.

Electric eels save the day, source: xkcd

I am wishing you happy Saturday's circuit designing!

Date:Sun May 31 10:40:00 CEST 2014


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