Subject: Re: 555 Clock Circuit
Date: Sun, 15 Sep 2002 12:00:08 +0200
Organization: Wanadoo, l'internet avec France Telecom
NNTP-Posting-Date: 15 Sep 2002 10:00:08 GMT
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> Hi all,
> I'm very new to electronics, and just wanted to start with something
> small. I was thinking of constructing a binary clock, and have drawn out
> my design. I was just wondering what to use for the impulse to my 4-bit
> binary counters. I was thinking of using a 555 IC set to 1hz. Is it
> possible to create a clock with the 555 IC, or will it never be accurate
> enough with my cheap materials to produce an Impulse that doesn't lose
> time? Is there any other device that I could use? If it is possible, I
> would like to use the 555, as I already have those on hand and available.
> Thanks for any help in advance,
It depends on the accuracy you need and your learning objectives. You won't
acheive the "real clock" frequency stability without a quartz crystal. A
straightforward way would be to use a CD4060 type of IC
(http://us.st.com/stonline/books/pdf/docs/2055.pdf ) which incorporates the
oscillator circuit and a divisor; this is very simple. Note however that if
you were using the most popular 32.768kHz crystals, it would provide 2Hz and
you would need to add another stage of division by 2.
Then if you want to learn the analog electronics, we could look at some
discrete quartz oscillators.