Problems with digital clock - Electronic Circuits Projects Diagrams Free

tphebert · 25th March 2008, 06:06 PM

Hello,

I builted a ttl digital clock, using 7490's, 7492's, and 7447. Its a 24 hour clock and works great. The only problem i am having is with the set switches. My first switch to turn the frequency , which is 1 hz, on and off to the clock works fine. The second switch is connected to the 1hz and the output is connected to the minutes 7490 Qa. The third switch is connected to the 1hz and the output is connected to the hour 7490 Qa. The minute switch when turned on will count to 5 the go to zero and then stay on zero. The hour switch will count to 3 go to zero then stay on zero. Will a capacitor help this problem,i haven't tried this yet.

RODALCO · 25th March 2008, 07:25 PM

Post us your diagramme.

It could have to do with no pull up or down resistors. reset and set TTL gates like to know what to do.

tphebert · 25th March 2008, 07:42 PM

I can have it up in a couple of days. Thanks

i'm in the process of drawing it now.

BeeBop · 25th March 2008, 10:30 PM

I think your problem may be switch bounce, but I'll wait until you post your schematic.
Anyway, I see you got your question posted.

tphebert · 27th March 2008, 08:38 PM

I'm looking in my book and that makes perfect sense. I'll try it Monday. Thanks

BeeBop · 27th March 2008, 08:55 PM

OK, keep us posted.

tphebert · 27th March 2008, 09:15 PM

I made my schematic today, but my friend accidently picked it up. i'm trying to see if she can email it to me. I worked all day on it.

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25th March 2008, 06:06 PM	(permalink)
tphebert	Problems with digital clock Hello, I builted a ttl digital clock, using 7490's, 7492's, and 7447. Its a 24 hour clock and works great. The only problem i am having is with the set switches. My first switch to turn the frequency , which is 1 hz, on and off to the clock works fine. The second switch is connected to the 1hz and the output is connected to the minutes 7490 Qa. The third switch is connected to the 1hz and the output is connected to the hour 7490 Qa. The minute switch when turned on will count to 5 the go to zero and then stay on zero. The hour switch will count to 3 go to zero then stay on zero. Will a capacitor help this problem,i haven't tried this yet.

25th March 2008, 07:25 PM	(permalink)
RODALCO	TTL clock problems Post us your diagramme. It could have to do with no pull up or down resistors. reset and set TTL gates like to know what to do. __________________ There are more ways to get to Rome. Electricity, Electric clocks, Meters and Trains are great.

25th March 2008, 07:42 PM	(permalink)
tphebert	I can have it up in a couple of days. Thanks i'm in the process of drawing it now.

25th March 2008, 10:30 PM	(permalink)
BeeBop	I think your problem may be switch bounce, but I'll wait until you post your schematic. Anyway, I see you got your question posted.

27th March 2008, 08:38 PM	(permalink)
tphebert	Thanks Beebop I'm looking in my book and that makes perfect sense. I'll try it Monday. Thanks

27th March 2008, 08:55 PM	(permalink)
BeeBop	OK, keep us posted.

27th March 2008, 09:15 PM	(permalink)
tphebert	Thanks I made my schematic today, but my friend accidently picked it up. i'm trying to see if she can email it to me. I worked all day on it.