Need to create a 5V clock signal

[Sneak33]

Hello, I'm needing to make a 5V clock signal every second or so. I can't seem to find a clock IC that outputs a 5V signal. Should I use a uC or is there an IC that I can use?

 

[daddles]

How about something simple like this?

 

[poor mystic]

Another good method is to count pulses of AC from the mains. This method has the advantage of great long-term stability, since mains frequency is very closely controlled. Usually a 'count to 50 (or 60) and then reset counter to zero' technique is used.

 

[Sneak33]

Thanks for the responses, I'm going to try the 7555 timer for low power consumption. Also. I can't use the AC mains because this circuit will be off the grid.

 

[(*steve*)]

7555 is also a good choice as its output swings closer to the supply rails (which is important if you have a 5V supply and want a 5V logic signal).

Note that it can't drive anywhere near as much current into a load as a 555 can. This doesn't sound like it will be an issue as I assume you're driving logic. (Hmmm, maybe not a good assumption...)

 

[KMoffett]

Hack a 1.5V battery desk or wall clock. Diode-OR the coil outputs and drive an NPN transistor to boost the signal to 5V. Small size, low power consumption, and very accurate.

Ken

 

[poor mystic]

Wow. That's practical! Can I suggest a little transformer instead of the transistor? I don't mean to say it's a better idea, but depending on circumstances...

 

[KMoffett]

I can't visualize the circumstances. But, try it and see.

Ken

 

[Sneak33]

Yes I have a 5V supply and I'm driving logic so I need a 5V logic signal. Also I want the duty cycle to be 50%. How would I change the duty cycle in KMoffett's design?

 

[(*steve*)]

To get a 50% duty cycle you could extend the pulses using a monostable. This would not be extremely accurate, but may be close enough.

It all depends on why you need the 1Hz signal and what you're doing with it.

 

[duke37]

The cmos 4047 can give an approximate 1 pulse/sec with an accurate 50% duty cycle. It does this by running at double frequency and dividing by two. It all depends on what you want.