What is the 555 timer I.C and why is it so famous?

I am new to electronics and I see the I.C 555 timer everywhere. What is it and why is it so famous. I found it's price to be only 15 cents in an indian store ( 6 rupees). So cheap. but so famous. Where can I find more info about it. What is it used for. What projects can I do with it? ---Thaks in advance. :) P.S: Please point to any youtube vids that explain I.C 555 timer.

Off topic: I'm reminded of 666 the Devil's Number. L.O.L XD

I shouldn't have to say what is so obvious but you can easily get answers to questions like this by doing a search. The English version of Wikipedia has a nice write up.


Sorry about that . I took a look at wikipedia's page(Brain error 100101: Not enough rum to handle the data) . Had a lot of info. Can you give me links to "good" youtube vids explaining the timer and a brief explanation.

Can you give me links to "good" youtube vids explaining the timer and a brief explanation.

I would have to do a search, just like you should. Just add 'youtube' to '555' when you search. You will only get 45 million hits, one of them is probably good.


Yeah! But I was hoping someone who actually have seen a video would help. I have a 24 k.bps speed and it's a pain. I'm sorry about that. :~

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

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.


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.

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.


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.