# digital clock using counters

Discussion in 'Homework Help' started by rpinnint, Nov 19, 2008.

1. ### rpinnint Thread Starter New Member

Nov 11, 2008
4
0
I need to design a Digital Clock in Multisim for my final project using Counters. Can anyone describe me the process of designing. I have to show minutes, hours, AM/PM and days of a week. Actually, I have studied about flip-flops and counters, but I don't know how to implement them in building a digital clock.
I saw a design online, but it used resistors, capacitors which are not allowed to use in my project.

Thanks.

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
This sounds like your last post. There are any number of ways to make a digital clock, but all use resistors and capacitors. Perhaps Multisim is more forgiving.

I guess if you use one of the CMOS TTL families that don't need pullup resistors and can specify a clock source, then you can just do a series of counters. Hopefully you can find a display that doesn't need current limiting.

Look up the data sheet on a 74HC160 to see how a decade counter works.

3. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
The display is the biggest problem, you HAVE to use resistors unless you are using a prepackaged module, which will have resistors in it.

Just a straightforward counter is no big deal, although if you intend to have push buttons you again have to have resistors. Why, because a button only defines one logic level, the resistor defines the other. These are called pull up/pull down resistors.

You really need to touch base with your professor and find out how he expects you do deal with these real world issues. If you never intend to set your clock (just make a simple counter) it is straight forward and easy. Assuming a clock base of 60 Hz (or 50 Hz if you aren't in the USA) you build a divide by 10, divide by 6, which brings it to one second, repeat, which brings it to one minute, then divide by 10 followed by divide by 2, which is hours. It's more of the same for the AM/PM and days of the week.

But somewhere I'm willing to bet you have to set the clock, which means resistors.