Help to get me started with a timer project

Hi I need a timer to operate a relay which will activate a Ham Radio WSPR beacon transmitter.

The requirements are that I need the realay to operate momentarily exactly at the start of every fourth minute and only on even numbered minutes so, 10:02/10:06/10:10.....etc.

So,just need some start off help with this. If I add an RTC to my Arduino, can I somehow interrogate the output of that to test for an even mintue and to test for a 4 minute pass? Maybe there's a better way to do this....

Thanks for any guidance folks

Regards Philip

That looks an easy project, but if you want it to keep accuracy over the months and years, you might be best with a GPS module to keep the time ( or if you are in Europe or the States there are radio time standards you can lock on to )

What exactly do you mean with "exactly"? According to you question it is not 100% clear if you just need the signal to be within 2 Minutes with some reasonable frequency deviation e.g. 2ppm (-->DS3223 RTC would do) or if you need to lock to an official signal --> GPS, DCF77 or other means come to mind. If you are in Europe I would go for DCF77 as it is cheap and easily acquired. I am preparing some blog entries to show how to lock DCF77 in the presence of significant noise. Will most probably appear 1st of January.

Thanks guys...

It would need to start on the minute with no more than a couple of seconds off... I'm in the UK and do have an MSF module so will have a read about that.. I also saw the adverts for the temperature controlled RTC modules which look accurate enough..

Just got to read up on how to get meaningful data from a clock module for this task..

Total noob to all this so some head scratching is called for..

Thanks again Regards


"RTC modules which look accurate enough.."

Thats the way to go then, ( I use GPS for clocks that are mounted on towers, so I dont want to go back every year if its a minute or two out )

Or the MSF ( we have no time signals that I know of here in South Africa unfortunately )

You say you have the Arduino, go through some of the examples, and simple projects, and you will soon be at a stage to write your sketch, and search for clocks or time on Arduino and take bits from other projects and play with them.

Once you have some sketch together, even if it doesnt work at all, post it here ( highlight it and select the # button above to save space here ) and there are some clever guys to help.

Will do.... thank you..