On Thu, 21 Jan 2010 16:15:53 -0800 (PST), Bill Sloman
>
> wrote:
> >> >> On Wed, 20 Jan 2010 21:18:43 -0800, John Larkin
Snip . . . .
>It's more that John Larkin is good at electronic design, and has
> >recognised precisely how useful the 555 is - which is to say, not a
> >useful device in most applications.
>
> Why then is it STILL one of the most widely used chips in existence?
>Legacy design. It worked for specifc applications, back in 1971 when
> Hans Camenzind designed it, and people have been copying these
> circuits ever since. Not because there isn't a better alternative -
> there almost always is - but because finding out what the better
> alternative is, qualifying the new component and explaining to the
> boss why you've wasted your time solving a non-problem all take time,
> and while the time is usually well-spent, in the long term, lots of
> people have more immediate short-term concerns.
Snip some more ....
Hans R Camenzind has some interesting information on IC design for those that would like to try their hand at it. Search for the article "Redesigning the old 555" by Hans Camenzind. It was published in the IEEE Spectrum Volume 34 Issue 9, Sept. 1997. IEEE Explore has a copy of the article.
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Google might have a link to a free copy of the IEEE Spectrum article.
A short article on Hans Camenzind and the 555 design history is available at
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The text and audio recordings of an interview with Hans on the design of the
555 and PLLs are available at
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It covers most of the info in the IEEE Spectrum article. There are however more detail and diagrams on the 555 design in the IEEE article.
I consider my self lucky to have experienced the days of BIG IC mask drawings and peeling Rubylift.
Enjoy the weekend
Gerhard van den Berg CSIR