In writing, do I need to define an abbreviation when it is already an industry standard term? When writing academic and scientific literature, are there any good guidelines to when you can omit defining an industry standard abbreviation? Are there any guidelines to where you can draw the line? When looking the this up I found a few sources like this blogpost that suggested using dictionaries - if it is in the dictionary as a word, you don't need to explain it. 

However, in my field (electrical engineering) there are many industry standard abbreviations that are not in any dictionaries. Examples would be terms like opamp (operational amplifier), ADC (analog-to-digital converter), CPU (central processing unit), MOSFET (Metal-oxide-semiconductor field-effect transistor). Applying their rule would mean I have to define every term, but this would seem somewhat excessive to me. 

How do I deal with industry standard terms that are still abbreviations? The safe bet would be to always define them in their first use, but are there any general rules to use when dealing with these?
Let us assume that your publisher / journal / conference / style manual has no restrictive guideline regarding abbreviations (otherwise, follow that guideline obviously in first place).

You do have to define every abbreviation. (As an example, I was confused yesterday by finding out that CRT is not only a cathode ray tube, but also the Chinese Remainder Theorem). Consider, e.g., the huge list at https://en.wikipedia.org/wiki/ADC . But you can do it in a clever, space-conserving way by


providing a list in an appendix,
defining them in footnotes on their first usage,
defining all of them in small size in a "preliminaries section" or in endnotes,
giving a reference to a standard Web site with the abbreviations you need,
giving a reference to your own Web page with the abbreviations you need, 
citing some electrical-engineering dictionary which defines them unambiguously the way you need,
…


Of course, pay attention that your paper reads well in first place; there may be no general advice on which of the above list items applies best to your paper.