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Topic: What is the 555 timer I.C and why is it so famous? (Read 1 time) previous topic - next topic

westfw

With a slow net connection, I wouldn't be looking for videos.
Here's a tutorial (search for "555 tutorial") that I found good enough to save in my bookmarks:
http://www.kpsec.freeuk.com/555timer.htm

floresta

#6
Nov 14, 2011, 03:24 pm Last Edit: Nov 14, 2011, 03:42 pm by floresta Reason: 1
I have a recommendation no matter which tutorial, article, or book you use.  

Always draw your 555 diagrams (or redraw the diagrams of others) with the same pins in the same location.  
 I always put two pins on each side of the box representing the 555.  
 Going clockwise from the top left they would be 8,4 on top, 3, 5 on the right, 1, 2 on the bottom, and 6, 7 on the left.

Now, when you compare all the multitude of diagrams you will find that there really are only two basic variants.
 The astable (square wave generators) circuits have a resistor between pins 6 and 7.
 The monostable (pulse generators) circuits have pins 6 and 7 connected together.


Don

floresta

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I have a 24 k.bps speed and it's a pain.

You should have mentioned that earlier.  I agree with westfw about the videos.

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What is it and why is it so famous.

It provides an easy and inexpensive way to generate fairly stable 'square' waves or trigger pulses.  
It is a linear device that does not require a regulated supply voltage.  
One thing that makes it easy to use is that the triggering is based on ratios.  That is, something happens when one voltage is a certain percentage of another (I don't remember all the details).  This means that if the supply voltage changes you can expect the frequency of your square wave to remain essentially the same.


Don

westfw

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why is it so famous

The wikipedia article is interesting; it includes some history:  http://en.wikipedia.org/wiki/555_timer_IC
The 555 is a chip designed near the beginning of the history of integrated circuits, and survives largely unchanged (at least in terms of external connections) 40 years after its birth.  It's simple enough to analyze at the transistor level (we did so !) and managed to implement such generic functionality that it is still useful.

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