A Newcomer (Digital Clock)

Hi Guys and Girls,
I am so glad to find such forum on the internet after about 4 days searching so I wish you can help me here.
First , I wannna inform you that I am a Student in The Faculty of Engineering here in Egypt but I have my own works too , So that's my first try to make my first Electronic Device, so forgive my unconscious mistakes in writing this topic.
Now I am trying to make a Digital clock using 555 to make a pulse , 7490 as a counter ,7447 as a BCD Decoder and a 7 segment displays.
Now I managed to make a units of the seconds I mean by the units the 0-9 part and went to make the tens part (0-5) but here is the problem as I can't force the 7490 to work as a 6 decade counter so please inform me on how to do with it and if you got any idea of R91,R92,R01 and R02 please tell me about them As I think that the problem is in joining those pins , Yours Aly

It is hard to build a clock with basic components, look at Sams clock: **broken link removed**

Secceeded

Hi Guys,
I finally managed to make the 74ls90 work as a 6 decade counter (0-5) and if anyone wants to know the way just ask about it and I'll be so glad to answer.
Yours, Digimanic

Re: Secceeded

Digimaniac said:

Hi Guys,
I finally managed to make the 74ls90 work as a 6 decade counter (0-5) and if anyone wants to know the way just ask about it and I'll be so glad to answer.
Yours, Digimanic

Click to expand...

A counter that counts from 0 to 5 is not a decade counter. It is a Modulo 6 counter. A decade counter is a Modulo 10 counter.

If you search my posts, you will find some Modulo 6 counters in answer to Alex (johnsoax) See the posts dated Mar 10 and Mar 12.

Len

could you please make a diagram on digital clock... i really need it

https://www.google.co.nz/search?q=TTL+decade+counter+with+7490&hl=en&lr=&start=40&sa=N


Try above link which has a simple TTL counter with a schema.

Hope it works

renren1227 I have just posted a thread with a complete TTL clock schema.

Digimaniac The R0¹ and RO² can be linked together for the normal clock applications same for the R9¹ and R9² terminals.

You leave these separated when a 24 counter without a 7400 is needed. For example: and can be wired by connecting the R0¹ from the hours and ten hours to the Q2 output from the 10 hour decoder.
Then the R0² from the hours and ten hours have to be connected to Q3 from the hour decoder.
The R9¹² can be bonded together to the negative rail.

hi guys.... i'am in the same proyects.. somebody can helpme?? Some people told me that i cant use the house electric line that contains a 60 Hz...
I hope some anwers...thank.. and sorry for may bad english, i'am a spanish talker...

well you can use the 60 Hz house electric line. I hope all u need for your project from the line is DC 5 or 12 Volts

dear aly i am m3tasm from egypt also this digital clock is my project this year i am just starting to search for suitable diagram if u find one please send me
also i will apply it in PCB
please help me

anthony123 said:

hi guys.... i'am in the same proyects.. somebody can helpme?? Some people told me that i cant use the house electric line that contains a 60 Hz...
I hope some anwers...thank.. and sorry for may bad english, i'am a spanish talker...

Click to expand...

It's been a common feature for many years-

HowStuffWorks "How Digital Clocks Work"

RODALCO said:

renren1227 I have just posted a thread with a complete TTL clock schema.

Digimaniac The R0¹ and RO² can be linked together for the normal clock applications same for the R9¹ and R9² terminals.

You leave these separated when a 24 counter without a 7400 is needed. For example: and can be wired by connecting the R0¹ from the hours and ten hours to the Q2 output from the 10 hour decoder.
Then the R0² from the hours and ten hours have to be connected to Q3 from the hour decoder.
The R9¹² can be bonded together to the negative rail.

Click to expand...

Hi RODALCO

The link does not lead to a thread or am I missing something?

This is Rodalco's TTL clock, good project with lots of info.

https://www.electro-tech-online.com/threads/ttl-clock-with-7447-7490-and-7400-ics.25628/

Mark