atomic clock ?

Hello i'm Ben and new to the arduino forum only been dabbling with arduino, mainly following a tutorial here or there.

but i have a project in mind (early stages) i've broken it down in to sections and cant find an answer for this section i'm either asking the wrong way or missing something. so if any one can point me in the right direction it would be much appreciated.

so i would time to make a time clock, (and by that i mean a relay where by you could set times when it would switch on/off).

but i dont want a backup battery, or connected to a network and obviously if power was to fail i would want it to keep time when it came back on line.

any thoughts ??

Thanks

A Real Time Clock may be what you want. They keep accurate time without external connections. They have a backup battery, but it is usually a small coin cell that lasts for years.

So called "atomic clocks" receive and decode the super accurate WWVB radio service in the North America, or DCF77 in Germany and some other parts of Europe.

You can buy inexpensive, compatible receiver modules and download the software for free, for example here.

OP.... are you talking about something like a rubidium clock module? If you are.... then quite accurate... but requires power all the time.

And not cheap.

Allan

How accurate do you need it to be?

So no backup battery. No connections to anything. Just an arduino which will figure out what time it is once it's switched on?

GPS has time, just use a GPS module.

Or use a board to connect to mobile phone network.

Lots of ways to update the time on boot up.