Help about building a Digital Clock

Thread Starter

zarabotkalesna

Joined Nov 22, 2015
18
Hello everyone.

I have intention to build a Digital Clock.
I want to reduce the number of ICs on breadboard to the minimum.

My first thought was to use 4026 counters because they have the BCD decoder integrated, but they count from 0 to 9 and I didn't find a way to reset them when count reaches 3, or 5 (if you know any method for resetting please tell me).

Second thought, to use 6 x 74LS193 (or 4510) counters plus 6 x 74LS47 (or 4511) BCD to 7-Segment Display Decoders plus 4 x AND gates for resetting 4 counters. That's a huge number of ICs so I don't want to use that option.

I also read that the NE555 is not very stable when it's used for large timing intervals, e.g. 1 minute or larger.
So I thought it might be wise to remove the "seconds" from my circuit and use a LM555 as a timer providing 1 minute clock (F = 0,0167Hz). But I would still have 4 counters and 4 BCD decoders. So I don't know how to reduce more this number of ICs.

I also don't want to use microcontrollers such as PIC or Arduino or others...

What would you suggest me?

Thanks,

Robert
 

ISB123

Joined May 21, 2014
1,236
You are going to have to ask Ahmed Mohamed, he is an expert when it comes to building digital clocks.


If you are new to electronics I would advise against building a digital clock since its fairly advanced project.
 

k7elp60

Joined Nov 4, 2008
562
Here is a circuit for a 1Hz clock. If you are in the U.S I would be glad to send you the parts, as I have multiple of each part.1hz.png
There still are digital clock IC's available that have all the necessary counters, decoders etc.
 

Sensacell

Joined Jun 19, 2012
3,432
A 555 timer circuit will not provide an accurate enough time base for a clock- unless you are ok with gaining / losing 15 minutes a day?

Most electronic clocks use:

(1) 32.768 Khz clock crystal oscillator.
-or-
(2) 50 / 60 Hz mains frequency as a time base.
 
the TS said:
Second thought, to use 6 x 74LS193 (or 4510) counters plus 6 x 74LS47 (or 4511) BCD to 7-Segment Display Decoders plus 4 x AND gates for resetting 4 counters. That's a huge number of ICs so I don't want to use that option.
Look at that 19x series to figure which one is more appropriate. You only need the gates for the count to 5 and reset.

24 hour is easier to do than 12 hr with AM/PM.

You can always multiplex the digits.

Don't forget leading zero blanking for a 12 hr clock.

A power line timebase works. So, does something that uses a 32768 Hz crystal. The power line has very good long term accuracy.
 

Thread Starter

zarabotkalesna

Joined Nov 22, 2015
18
Look at that 19x series to figure which one is more appropriate. You only need the gates for the count to 5 and reset.

24 hour is easier to do than 12 hr with AM/PM.

You can always multiplex the digits.

Don't forget leading zero blanking for a 12 hr clock.

A power line timebase works. So, does something that uses a 32768 Hz crystal. The power line has very good long term accuracy.
Thank you all guys.

I couldn't find that IC... can you please provide me a link or something?

Thanks
 

AnalogKid

Joined Aug 1, 2013
10,986
First, you can surf for digital clock schematic and get tons of schematics to help you decide on chip technology/count/complexity.

Please give us a little background. What is your intent for the project? you said no PIC and I totally support that, but it still leaves some options. All TTL / CMOS, a fully integrated clock chip, direct drive displays, multiplexed displays, power line reference clock, crystal oscillator...? Also, what is your skill set for designing and building electronic circuits? Will this be hand-wired on perf board or are you going for a pc board? Is a kit that is all TTL chips and a pc board out of the question?

The more we know about the entirety of your project, the better the guidance will be.

ak
 

Picbuster

Joined Dec 2, 2013
1,047
Building a clock for normal use is simple.
Use a lm8705, fuse, 3 caps, 3 resistors, pic one, xtal and a display.

When wanted I can supply schematic and basic program.
 

hp1729

Joined Nov 23, 2015
2,304
Hello everyone.

I have intention to build a Digital Clock.
I want to reduce the number of ICs on breadboard to the minimum.

My first thought was to use 4026 counters because they have the BCD decoder integrated, but they count from 0 to 9 and I didn't find a way to reset them when count reaches 3, or 5 (if you know any method for resetting please tell me).

Second thought, to use 6 x 74LS193 (or 4510) counters plus 6 x 74LS47 (or 4511) BCD to 7-Segment Display Decoders plus 4 x AND gates for resetting 4 counters. That's a huge number of ICs so I don't want to use that option.

I also read that the NE555 is not very stable when it's used for large timing intervals, e.g. 1 minute or larger.
So I thought it might be wise to remove the "seconds" from my circuit and use a LM555 as a timer providing 1 minute clock (F = 0,0167Hz). But I would still have 4 counters and 4 BCD decoders. So I don't know how to reduce more this number of ICs.

I also don't want to use microcontrollers such as PIC or Arduino or others...

What would you suggest me?

Thanks,

Robert
Are chips like the MM5314 still available? Single chip clocks.
 
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