# Digital Clock Using Gates

Discussion in 'The Projects Forum' started by ryandezz, Jan 2, 2011.

1. ### ryandezz Thread Starter New Member

Dec 4, 2010
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i'm building a circuit using this diagram,is there any problem with the circuit above?i realised there's a frequency generator needed for pin 6 of the multiplexer...is there any way i know what frequency to insert in there?and if i were to replace it with a 555 timer,how would i do it?Any suggestions are most welcomed,i want to try to do this circuit.thank you in advance!

Dec 4, 2010
4
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3. ### edgetrigger Member

Dec 19, 2010
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i don't see any circuit. pls reload it.

half sec pulse or 1 sec pulse will serve as a clock source, and 555 is good enough for this job.

4. ### hgmjr Moderator

Jan 28, 2005
9,030
214
You can use a 555 but only if you are not interested in maintaining accuracy. For accurate time-keeping you will need to use a crystal oscillator. Many solutions use a 32768 Hertz clock that is divided down to 1 Hertz.

hgmjr

5. ### ryandezz Thread Starter New Member

Dec 4, 2010
4
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the link to the diagram is this>> http://img171.imageshack.us/i/ttlclock2ug7.png/

how would i connect it using the 555 timer? i've searched around but i dun really understand the diagram such as stated in this link

i notice one of the pin on the 555 timer has the frequency symbol....does it mean i need to connect to the frequency generator?

and do i need to consider connecting to the other ic's?how can i do it?all your feedbacks are greatly appreciated!

6. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
The imageshack link is unreadable, the resolution is just too low to make out any details.

A better AAC link would be something like this, I drew it up for beginners in logic.

There are many chips that will plug into the boxes shown on this block diagram, many.

A 555 is low accuracy, it drifts. A crystal oscillator is much more accurate, and is what most digital watches use.

Quick note, this site has its own albums, it is a lot easier to use the local albums for posting pictures that an outside website.

Another good website that may have what you want is Bowden's Hobby Circuits. It has several schematics of various digital clocks.

Last edited: Jan 2, 2011
7. ### ryandezz Thread Starter New Member

Dec 4, 2010
4
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thank you,i will slowly look into it