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Re-examine assumptions for better designs

Posted: 18 Feb 2008 ?? ?Print Version ?Bookmark and Share

Keywords:recheck assumptions? debug design? logical troubleshooting analysis?

We design and debug using many assumptionsfor example, how much to bypass those power supplies, what constitutes an adequate ground, and where to separate analog and digital grounds. Some of these assumptions are apparent, but many of them are built into our thinking and not called out explicitly.

Experts, tutorials, experience and learned lessons have embedded them in our engineering psyche.

Working with these assumptions is usually a good thing. This is because without them, little would be done in any reasonable time, and we'd make mistakes that could have been avoided. We'd be learning the hard way what others already have found out.

At the same time, these spoken and unspoken assumptions can blind us when things are, to put it bluntly, different.

Out-of-the-box thinking
There are occasions when the standard guidelines (also called "rules of thumb") don't apply. Sometimes, you have to ground the other end of that cable's shield or ground both ends, even though it's usually better to ground just one.

Or sometimes, things just don't add up right, and some out-of-the-box diagnostic thinking is needed so you can figure out why the bugs in the system won't succumb to any.

Two reasons
It's not just our niche that needs reassessment of assumption. A January 2007 article in Popular Mechanics entitled "Your Dad Was Wrong" showed that a lot of traditional automotive wisdom no longer holds up. For example, "let the engine idle to warm up on cold days" is not true today.

There are two reasons your assumptions need to be re-examined. First, the conditions under which they are valid may not be present in a specific situation. Second, things change. When you have technology that changes as quickly as it does in our field, there are eternal truths but also constant revisiting of the implications of those truths.

Perhaps we should remember that there is nothing certain except death and taxes. I would add to these Maxwell's equations, F=ma, E=mc2, and only a few others.

- Bill SchweberSite Editor, Planet Analog

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