help in digital clock project using 555 timer

Hello,
I have been asked to design a Digital clock using a 555 timer as clock generator and a 7-segment display to display clock.

I have no idea how to start, could u give me some hints.

many thanks,,,,,,

 

What kind of circuits are you allowed to use in your assignment?

 

the gates to be used were not specified, if it is possible, I need to use the simplest available gates. The thing is that I don't even know how to use 555 timer in this case,

 

You will need to use some logic ICs.

TTL and 4000-series CMOS have been around for years, and are still pretty readily available. You will need to chose one logic family to work with.

TTL (54xx/74xx series) requires a voltage supply of 5v; minimum 4.5v max 5.5v.

CMOS can work over a voltage range of around 3v to 16v, and requires much less current than TTL.

This link has pages that describe in general terms a good portion of TTL (74xx series) and CMOS (4xxx series) ICs:
http://www.kingswood-consulting.co.uk/giicm/

A couple of handy ICs that you will need are BCD to 7-segment drivers.
There are TTL versions in the 7446, 7447
CMOS has the 4033, 4511 and a few others.

You will need some decimal/BCD counters (NOT Decade/Johnson counters). I suggest that you avoid HEX/binary counters, as that will make extra work for you.

You may also need AND, OR, NAND, NOR, XOR gates and inverters.
The 4093 is a very handy IC to know about; it is a quad Schmitt-trigger NAND gate. You can construct any other logic gate using combinations of NANDs.
http://en.wikipedia.org/wiki/NAND_logic
The Schmitt-trigger input is very useful for "squaring up" slowly transitioning waveforms.

 

Thanks a lot Bill_Marsden, I started to get the idea, I am stuck now to get an output pulse from the 555 with a width of 1s.

-am I right in the 1s width?-

 

mr.Bill, I have succeeded in connecting the six 74ls160 ICs to the 7-segment displays. I tried giving clocks with different frequencies from a function generator. The seconds, minutes and hours are being showed correctly. --:--:--. My problem now is to get the right input frequency to the first counter, what's the right frequency? I want to try supplying it firstly using the function generator then I will design the 555 timer according to this frequency.

(first counter is for seconds --:--:--'the one in red')

 

- 60 Hz.

(pad, pad, pad.)

 

@mr.harm
What happened to your ingenuity and engineering gene?

 

tel me how do i reset my clock from 13 to 01. it can be easy to bring in 00 but its difficult for me to make 00.