How to make a 12 hour clock - Electronic Circuits Projects Diagrams Free

IlordrossI · 22nd February 2005, 04:25 AM

I am trying to build a digital clock using
( 6 ) 7492 Binary Counters
( 6 ) 7447 BCD to 7-Segment Decoder/Driver
( 6 ) 150 Ohm Resister Packs
( 6 ) 7 Segment Displays

I have figured out how to make the seconds and minute’s sections of the clock. But I am unable to make the 12-hour section. I just can't figure out the right way to connect the 7492 counters to the 7447 BCD Decoders. Anyone who might know please help me out. I will be forever great full.

bonxer · 22nd February 2005, 03:36 PM

You've managed to take a 7492's output of 0-1-2-3-4-5-8-9-A-B-C-D and correct it to 0-1-2-3-4-5-6-7-8-9-reset, yet you can't make a simple one digit correction built onto that for the 12 hour? :shock: I'm assuming that instead, you used a 7490 to get 0-9 for the ones digit, and then a 7492 to get 0-5 for the tens digit. If so that makes a lot more sense, as there would be no correction logic necessary at this point.

Anyway, on to correcting a 7492's output to result in 12-01-02-03-04-05-06-07-08-09-10-11. Use a truth table and Karnaugh maps to transfer from your given bit patterns to the desired bit patterns.

Code:

  Given         |  Desired
                |
  Q3 Q2 Q1 Q0   |  Ten-HR   1-HR      D4 D3 D2 D1 D0
----------------+------------------+------------------
0  0  0  0  0   |       1      2   |   1  0  0  1  0
1  0  0  0  1   |       0      1   |   0  0  0  0  1
2  0  0  1  0   |       0      2   |   0  0  0  1  0
3  0  0  1  1   |       0      3   |   0  0  0  1  1
4  0  1  0  0   |       0      4   |   0  0  1  0  0
5  0  1  0  1   |       0      5   |   0  0  1  0  1
8  1  0  0  0   |       0      6   |   0  0  1  1  0
9  1  0  0  1   |       0      7   |   0  0  1  1  1
A  1  0  1  0   |       0      8   |   0  1  0  0  0
B  1  0  1  1   |       0      9   |   0  1  0  0  1
C  1  1  0  0   |       1      0   |   1  0  0  0  0
D  1  1  0  1   |       1      1   |   1  0  0  0  1

You'll feed D3-D0 into the 7447 to get your hours digit output. As for the ten-hours output, it looks kind of funny to have a leading zero, so it's simple. It's either completely off, or it displays a 1. Just connect your D4 line straight to your 7 segment's B and C lines, so when D4 is on, a 1 displays, when D4 is off, nothing displays.

Another possibility is that you use a 7493 chip, which counts up to 16. When it starts out at 0, simply convert that to a 12. All of the rest of its outputs will be correct. Then when it reaches its own 12, have that trigger a reset so it starts the cycle all over again.

gifthot · 24th February 2005, 01:07 AM

Can you provide the circuit to me
Thank you very much
Best reqards

bonxer · 24th February 2005, 07:04 PM

Here's a quick MS-Paint diagram. I leave it up to you guys to do the table correction. Part of the fun of electronics is coming up with clever solutions to small problems, as opposed to just plugging stuff in and seeing that it works.

If you're still stuck, I'll fill in more details if needed.

FRIED · 25th February 2005, 01:50 PM

You need to leave Q0 disconnected on displaying '92s and use Q1-Q3 as inputs to the '47

bonxer · 25th February 2005, 03:35 PM

Good call! The /2 input is disconnected (or perhaps grounded would be better), which leaves Q0 output idle. Q1-Q3 are the only active pins feeding into the 7447.

mahmoud1919 · 26th June 2007, 06:29 PM

i make it its easy but its better to make the counter is 7490 BCD because this counter is -ve edge and u dont have to use 6 150 Ohm Resister i make it u can use ine resistace 1K ohm and i am sure from what i say i make it by my hand if u want to see my desgin send to me mail

**Nigel Goodwin** · 26th June 2007, 07:08 PM

Quote:

Originally Posted by mahmoud1919

i make it its easy but its better to make the counter is 7490 BCD because this counter is -ve edge and u dont have to use 6 150 Ohm Resister i make it u can use ine resistace 1K ohm and i am sure from what i say i make it by my hand if u want to see my desgin send to me mail

You might perhaps try reading the date on the threads?, this one is over TWO YEARS OLD!.

mahmoud1919 · 26th June 2007, 07:22 PM

what i mean if he use a -ve edge counter he dont need to check on the 9 to make pulse to the next counter because u will take the LSB and connect it by the clock of the next counter os with u get number 8,9(1000,1001) and u take the LSB and -ve edge so when the LSB get zero(0) so the next counter will take pulse to change the number so u dont need to check on the 9 to make all the counter connect to each other and use of variable resistace is better because he can control the density of ligth of the 7-Segment by put all the 7-segment on one Vcc and before the connection by the Vcc connect the variable resistace of 1K ohm i think this is better than this

mahmoud1919 · 26th June 2007, 07:29 PM

http://pdf1.alldatasheet.com/datashe.../ETC/7447.html
this is the decoder
3,4,5 no connection
7,1,6,4 the input
3 is the check that u connect the 7-segment rigth beacuse when u connect this by ground or Vcc i dont remmber but u will got 8 on the 7-segment and this is the check

mahmoud1919 · 26th June 2007, 07:32 PM

and about the counter i use 7490 and i dont know what about this counter
7490
http://pdf1.alldatasheet.com/datashe.../ETC/7490.html
this is the counter
connect 11 by 1
13,4 mean no connection
(i do it as aproject in my colleage)
goodluck

mneary · 26th June 2007, 08:06 PM

@mahmoud1919:
Your eagerness to help is admirable, but -

The original poster reported that the problem is solved, more than two years ago.
(He) has not posted on this board since December 2005.

mahmoud1919 · 26th June 2007, 08:31 PM

i am so sry but i dont read it
i want to help that is all

mneary · 27th June 2007, 12:11 AM

As I said, your eagerness is admirable. I just didn't want you to waste a lot of time on an old problem.

regards,
Mike

22nd February 2005, 04:25 AM	(permalink)
IlordrossI New Member	How to make a 12 hour clock I am trying to build a digital clock using ( 6 ) 7492 Binary Counters ( 6 ) 7447 BCD to 7-Segment Decoder/Driver ( 6 ) 150 Ohm Resister Packs ( 6 ) 7 Segment Displays I have figured out how to make the seconds and minute’s sections of the clock. But I am unable to make the 12-hour section. I just can't figure out the right way to connect the 7492 counters to the 7447 BCD Decoders. Anyone who might know please help me out. I will be forever great full.

22nd February 2005, 03:36 PM	(permalink)
bonxer Experienced Member	You've managed to take a 7492's output of 0-1-2-3-4-5-8-9-A-B-C-D and correct it to 0-1-2-3-4-5-6-7-8-9-reset, yet you can't make a simple one digit correction built onto that for the 12 hour? :shock: I'm assuming that instead, you used a 7490 to get 0-9 for the ones digit, and then a 7492 to get 0-5 for the tens digit. If so that makes a lot more sense, as there would be no correction logic necessary at this point. Anyway, on to correcting a 7492's output to result in 12-01-02-03-04-05-06-07-08-09-10-11. Use a truth table and Karnaugh maps to transfer from your given bit patterns to the desired bit patterns. Code: Given \| Desired \| Q3 Q2 Q1 Q0 \| Ten-HR 1-HR D4 D3 D2 D1 D0 ----------------+------------------+------------------ 0 0 0 0 0 \| 1 2 \| 1 0 0 1 0 1 0 0 0 1 \| 0 1 \| 0 0 0 0 1 2 0 0 1 0 \| 0 2 \| 0 0 0 1 0 3 0 0 1 1 \| 0 3 \| 0 0 0 1 1 4 0 1 0 0 \| 0 4 \| 0 0 1 0 0 5 0 1 0 1 \| 0 5 \| 0 0 1 0 1 8 1 0 0 0 \| 0 6 \| 0 0 1 1 0 9 1 0 0 1 \| 0 7 \| 0 0 1 1 1 A 1 0 1 0 \| 0 8 \| 0 1 0 0 0 B 1 0 1 1 \| 0 9 \| 0 1 0 0 1 C 1 1 0 0 \| 1 0 \| 1 0 0 0 0 D 1 1 0 1 \| 1 1 \| 1 0 0 0 1 You'll feed D3-D0 into the 7447 to get your hours digit output. As for the ten-hours output, it looks kind of funny to have a leading zero, so it's simple. It's either completely off, or it displays a 1. Just connect your D4 line straight to your 7 segment's B and C lines, so when D4 is on, a 1 displays, when D4 is off, nothing displays. Another possibility is that you use a 7493 chip, which counts up to 16. When it starts out at 0, simply convert that to a 12. All of the rest of its outputs will be correct. Then when it reaches its own 12, have that trigger a reset so it starts the cycle all over again.

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24th February 2005, 01:07 AM	(permalink)
gifthot New Member	Can you provide the circuit to me Thank you very much Best reqards

25th February 2005, 01:50 PM	(permalink)
FRIED Experienced Member	You need to leave Q0 disconnected on displaying '92s and use Q1-Q3 as inputs to the '47

25th February 2005, 03:35 PM	(permalink)
bonxer Experienced Member	Good call! The /2 input is disconnected (or perhaps grounded would be better), which leaves Q0 output idle. Q1-Q3 are the only active pins feeding into the 7447.

26th June 2007, 06:29 PM	(permalink)
mahmoud1919 New Member	i make it its easy but its better to make the counter is 7490 BCD because this counter is -ve edge and u dont have to use 6 150 Ohm Resister i make it u can use ine resistace 1K ohm and i am sure from what i say i make it by my hand if u want to see my desgin send to me mail

26th June 2007, 07:22 PM	(permalink)
mahmoud1919 New Member	what i mean if he use a -ve edge counter he dont need to check on the 9 to make pulse to the next counter because u will take the LSB and connect it by the clock of the next counter os with u get number 8,9(1000,1001) and u take the LSB and -ve edge so when the LSB get zero(0) so the next counter will take pulse to change the number so u dont need to check on the 9 to make all the counter connect to each other and use of variable resistace is better because he can control the density of ligth of the 7-Segment by put all the 7-segment on one Vcc and before the connection by the Vcc connect the variable resistace of 1K ohm i think this is better than this

26th June 2007, 07:29 PM	(permalink)
mahmoud1919 New Member	http://pdf1.alldatasheet.com/datashe.../ETC/7447.html this is the decoder 3,4,5 no connection 7,1,6,4 the input 3 is the check that u connect the 7-segment rigth beacuse when u connect this by ground or Vcc i dont remmber but u will got 8 on the 7-segment and this is the check

26th June 2007, 07:32 PM	(permalink)
mahmoud1919 New Member	and about the counter i use 7490 and i dont know what about this counter 7490 http://pdf1.alldatasheet.com/datashe.../ETC/7490.html this is the counter connect 11 by 1 13,4 mean no connection (i do it as aproject in my colleage) goodluck

26th June 2007, 08:06 PM	(permalink)
mneary Experienced Member	@mahmoud1919: Your eagerness to help is admirable, but - The original poster reported that the problem is solved, more than two years ago. (He) has not posted on this board since December 2005.

26th June 2007, 08:31 PM	(permalink)
mahmoud1919 New Member	i am so sry but i dont read it i want to help that is all

27th June 2007, 12:11 AM	(permalink)
mneary Experienced Member	As I said, your eagerness is admirable. I just didn't want you to waste a lot of time on an old problem. regards, Mike