TTL Clock with 7447 7490 and 7400 IC's

[Nigel Goodwin]

I disagree, If one uses a cmos version and a good quality film capacitor the frequency can be adjusted to exactly 60Hz and it will be very stable.

Sorry, it would be rubbish! - a crystal is hundreds of times more accurate and stable (if not thousands?) than an RC oscillator.

 

[Sceadwian]

As far as temperature stability goes, RC oscillators are horribly unstable unless you use matched NTC and PTC resistors and caps for the circuit, at which point why not just use a crystal...

 

[Nigel Goodwin]

As far as temperature stability goes, RC oscillators are horribly unstable unless you use matched NTC and PTC resistors and caps for the circuit, at which point why not just use a crystal...

And even using the matched temperature coefficient components it's still a LONG way short of a crystals performance! - it makes no sense NOT to use a crystal.

 

[berem]

please help 7400 oscillator

hello..
I'm Turkish.my english is very bad.but I must to write the mail.
I want to a oscillator circuit with 7400.Do you understand me.please help me.
have a good time...

 

[RODALCO]

berem, What do you want to drive with it ?

What frequency do you require ?

The 50 or 60 Hertz mains frequency is very accurate long term.
Some short term variations may happen, but over a 24 hour period it is very accurate.

A 7400 is a NAND gate, in TTL it is most often use to divide 12, 24 or 60 counters.

Regards, Raymond

 

[Diver300]

You can use an oscillator. They are as easy to use as a 7400 IC. Just provide 5V and the output oscillates at TTL levels, or CMOS if you want.

You can now buy oscillators that contain the dividers so you can obtain them at low frequecies like 50 or 60 Hz.

 

[Top Cap]

Hi Barem, if you want to make your own basic crystal oscillator then this site may help you:-
http://www.z80.info/uexosc.htm

I tend to agree with the other posts on here though, you can by a ready made crystal oscillator in a can, same size as a 14 pin chip, some even have a trimmer for accurate setting.
Les

 

[iyung_w]

another version of the TTL clock

Hi all, This is my version of the TTL clock, it displays 0:00:00 to 23:59:59. [REVISED]
Make sure you read the datasheet to the TTL IC's on the +5V and GND connection pin.

Schematic:
http://www.geocities.com/iyung_w/files/24hrs_clock.pdf

Datasheet:
**broken link removed**

Good Luck!

 

[RODALCO]

Thanks for posting that schema.

Should't it be 23:59:59 ?

Cheers, Raymond

 

[zhdsdf]

hi to all.....i m new member......i have to make a digital clock using TTL IC's 7492,7447,74160,7490 etc..............i have read all the threads............but i was very astonished that there was not pin diagrams of these IC's ........any one who can tell me the whole schematic diagram please tell me as soon as possible.............thaks

 

[blueroomelectronics]

Just download the IC datasheets for the pin diagrams. Prefix SN to make the google search easier. SN7492, SN7447 etc...

 

[Krumlink]

Just download the IC datasheets for the pin diagrams. Prefix SN to make the google search easier. SN7492, SN7447 etc...

You should check out my binary clock (works awesome, uses up quite alot of milliamps (about 500), so it is kind of pointless to run it battery power. I should switch it over to wall plug in

Mine was a ton of work, but is really cool. The attachments are the pictures of it. (wrong Computer profile, cant access my pictures )

 

[RODALCO]

zhdsdf

Try to Google for data sheets, most of these are standard TTL IC's, otherwise try to get hold of the TTL Cookbook from Don Lancaster.

Cheers, Raymond

 

[berem]

thanks

hi.
thanks for your answer.but I relinquished them.anymore it isn't my project.

 

[Krumlink]

aw, you would have had fun with it like my clock

 

[RODALCO]

Ok here are some photo's of the diagrammes to make it easier for our members who can not find these TTL IC details.

This info is from my TTL Cookbook which i bought years and years ago, but occasionally these are for sale on Ebay.

Info for the 7400, 7408, 7447, 7490, 7492 and 74160 attached.

There are very good PDF files on the internet available as long the LS or SN is put in the search engine ( 74LSxx ) or ( SN 74xx )

Hope this wil help,

Regards, Raymond

edited to improve picture details

 

[blueroomelectronics]

I've got those somewhere, Don Lancasters books were great.
https://www.tinaja.com/

 

[zhdsdf]

thanks for reply.............
i think now i will be able to solve my problem.......
thanks to alll

 

[zajioftheasuka]

hello guys...im a newbie here...

i need ur help, i've been making my own digital clock using this diagram...
**broken link removed**

i already connected the minute and second digits and its working, but the problem is that it doesnt start at 00:00 rather 15:14...pls help me guys...

and if anyone knows how to add a set and reset button...

i appreciate ur help guys, thnx in advance...


and BTW, ive also tried the schema posted by rodalco but i can't understand the labels on the 7490...if its R0(1),R0(2),R90,R91...

i'd appreciate it if anyone can post a much more detailed schematic...

thnx guys...

 

[iyung_w]

I am not trying to discourage you, but actually its a clock, then you don't need to have the clock at 00:00 everytime you turn it on, since you already have fast and slow counter to set your clock.

Take a look at the 7490 datasheet for pinout here:

**broken link removed**

cmiiw, to reset the Decade Counter, MR1 and MR2 pin set to Hi. Then it will give Lo output to Q0-Q3 which will make the 7447 set the 7segment to display 0. But it looks like your 10th hour can only display '1' and blank, not '0' and '1'.

good luck!