Picture of 12 Hour TTL clock
This was the final project for my Digital 2 class it was so well received that I thought I would share it. To begin the project I created the circuit virtually. By starting this way I was able to work a lot of the kinks out of my design while also making sure to use only the parts that I had in my kit.

Step 1: Gather your parts

Picture of gather your parts
Parts List:
1. 555
2. 7408 AND gate
3. 7447 BCD to decimal decoder
4. 74LS90 Decade counter
5. 74LS93 Counter
6. 74LS76 JK flip flop
7. 331 resistor chip
8. 104 capacitor, 1µf cap, and a 10µf cap
9. (2) 503 potentiometers
10. 10K potentiometer
11. (6)or (3 dual) seven segment displays (common anode)
christanto7 months ago
christantoangga1@gmail.com . My email sir
christanto7 months ago
Sir please can you give me the schematics for my final task school sir.. pleasee..

sir is that a home-made trainer.....and please make the pic. clear so that i can see the PICS. clearly....thank you???

can you please send me the schematics??
cdurfey10 months ago

Please send me a copy of your circuit diagram with the complete parts list. I would like to make this with my son. Thanks


LiQ10 months ago

please send me a copy of your circuit diagram !! help me !!

gmail : tanphat250394@gmail.com

thank you very much

please send me a copy of your circuit diagram !!

help me !!

yahoomail :: vincentgonzales372@yahoo.com

jnimes1 year ago

the list of materials is not complete...

what diode did you use?

what value of resistor if I can't buy anywhere the 331 resistor chip?

what is 503 and 205 in the picture? is 503 really a potentiometer but it looks like a ceramic resistor?

also, in the schematic you provided there is the 3 input and gate which is 74ls11 if i'm not mistaken but you didn't include it in the list...

the schem you provided is blurred, can't read the labels of each component clearly....

i hope you would reply immediately ^^ i have read other comments saying it is working and I want to make it to but there are some missing information in your post. Thanks in advance :D

rezacumi1 year ago
does it can set the clock time?
imsajid2 years ago
Sir please send me the clear circuit. I have to submit my project report ..... please Sir My Email id is: Almurshid5@gmail.com
ughani22 years ago
plz send me circuit diagram for 12 Hour TTL clock
my email
darthneo3 years ago
Wow this is very impressive!

Can i ask how accurate your clock is with the 555 timer?
josgrg (author)  darthneo2 years ago
It is not as accurate as a real clock it loses appox. .68 sec a day which doesn't sound like much but over a large period of time say a week or a month the lose is significant.
waddaphak3 years ago
good day sir! can i have a copy of your pdf without having PRO ACCOUNT please.. ill be using it as a references in our on going project.. thanks
josgrg (author)  waddaphak2 years ago
I no longer have a copy of it. But if you do a internet search for a diagram you should find one easily.Sorry
Orion16152 years ago

I was wondering if you could use these parts to make a simple 30 second counter that would activate something or bleep when it comes to 0, with one button to reset it while its counting...

Its for a tiny little project so the simpler the circuit, the better, and this seems like a whole lot more advanced circuit... Any ideas?

josgrg (author)  Orion16152 years ago
Yes, it is possible but it is not very efficient or accurate. Because the 555 is used for a 1 Hz square wave the "timing " is not as stable as it needs to be for an actual timer.I would use a RTC ( real time clock) IC for the circuit you want it would make eveything much simpler.
trialex3 years ago
Wow excellent work!

I've been mucking around with a design using TTL chips like the very useful 4026 which combines a decade counter and 7-seg decoder into one chip. Of course nothing is simple, and I think I need a transistor driver between the 4026 and the LEDs, thereby negating the "all-in-one" advantage of the 4026.

How much current does your clock draw?
chochinooo3 years ago
this was awesome..thanks much but what was the led for??..
josgrg (author)  chochinooo3 years ago
The LED indicates A.M. or P.M.
duggerpato4 years ago
I did a counter on a giant breadboard similar to this in a digital electronics class too. Fun fun.