Step 1: Find out about the master clock you are replacing

Picture of Find out about the master clock you are replacing
The master clock that was replaced by this project was a "Rauland 2490 Master Clock". It had stopped working during a storm with heavy lightning. The slave clocks were moving very quickly (continuous synchronization signal), and the master clock was subsequently shut off.

Thus the clocks in the school all showed about the same time, but all wrong, and always wrong. This proves that the expression "even a broken clock is right two times a day" is false.

You will need to know:
* what protocol is used by the slave clocks (can probably guess based on the make of the clocks)
* how many zones are used for bells (indoor, outdoor, different buildings etc)

Your school (or other location) may even have documentation in the form of wiring diagrams. These can be very helpful when installing the new clock.

KC0GRN5 years ago
I wonder if this system could be used in a smaller scale, and without the slave clocks.

Here is my situation. My church has a manual electric buzzer system (push one of the 3 buttons in the church and the buzzers go off, it only buzzes for as long as you hold the button) for signaling Sunday School, Church and Wednesday night programs.

What I thought would be nice is to have an arduino controlled clock to automatically sound the buzzers at the proper time intervals, and for the proper length of time, like a short or a long buzz to signal a 5 minute warning.

Obviously this doesn't need slave clocks, it just needs to operate a relay switch to take over for the manual buzzer buttons.