Step 1: 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.

Superb project, <br>Please instruct me how to set alarm without using java programming i.e only use of hyper terminal etc, Bcz Java code doesn't work in my system.And please send schematic i would be a great help to me. <br>regard <br>Krish <br>
This is awesome - I realise this is an old project but it's a perfect solution for multiple automated bells in the small factory I work in. Is there a way to get a schematic for this?
could it start a motor instead of a bell
Hey,<br>Just a quick note to say that this is an awesome project. <br>Cheers!<br>Zak
Most cool. Looking to replace a brain-dead (no NTP support) expensive dukane controller. Has this been tested with Dukane clocks, to your knowledge?
Nice instructabe!<br /> <span class="short_text" id="result_box"><span style="background-color: rgb(235,239,249);">How do I download the </span></span>schematics<span class="short_text" id="result_box"><span style="background-color: rgb(235,239,249);">?</span></span><br /> thanks.<br />
&nbsp;A schematic would be reeeaaaaaalllllllyy helpful! &nbsp;I've got an old school slave clock that will look great in my kitchen, and is my reason for getting into arduino projects (and, by extension, electronics). &nbsp;So a schematic would be a huge help!
As an art project, I need to stop an analog clock (which would most likely be a slave clock) for 2 minutes and restart it after the two minutes have passed. The clock then needs to switch back to display the correct time. Could you think of a way of doing this?<br />
Hmm. The slave clocks in the school run on 24V 60Hz, and they just keep running. The correction signal, depending on length, moves the hands to the next hour, or to six o'clock. You might be able to use these, 2 cases:<br /> (1) You only stop the clock 2 minutes before the hour, and then apply the correction signal on the hour. You could only stop/start once per hour though.<br /> (2) If you used a higher frequency (120Hz) the clock would run twice as fast, maybe that could be useful?&nbsp;<br /> <br /> It would be so much simpler with a digital clock!&nbsp;<br /> <br /> Perhaps taking an analog clock apart could help, I don't know exactly how they work.&nbsp;<br /> <br /> Also, there are other slave clock protocols. Some advance only when sent a signal by the master clock. I think these are referred to as &quot;impulse&quot; control. I don't think they have second hands though. Maybe driving the second and minute hands separately somehow can achieve what you need.&nbsp;<br /> <br /> Sorry I don't have a clear answer. I'll think some more and try to come up with something!<br />
Hmm, I didn't even know there was a correction signal. how does that work? <br /> <br /> I could go with option 1 then. <br /> <br /> How does the master clock know the position of the hands on the slave clock?<br /> <br /> Thanks for replying so quickly.<br /> <br />
&nbsp;The master clock does not know the position of the hands, but after the hourly sync (I said correction, but sync is better) the slave clock minute hand will be in a known state. Similarly, after the 12 hour sync, the hour hand will be in a known state. The second hand just keeps going.&nbsp;<br /> <br /> So if the slave clock is slow, it will be corrected. If it is a little fast, nothing happens (I think), if it is very fast (or ahead), it will be an hour ahead after the sync. Hence the 12 hour sync, when everything will be 6 (pm or am looks the same).&nbsp;<br /> <br /> There are some different protocols. &quot;My&quot; clocks use the National, or Standard Time protocol. There are some other similar, but slightly different ones.&nbsp;<br /> <br /> For you, it would be a simple matter to cut the power for two minutes, and the &nbsp;clock hands would not move (not the second hand either). Turn on the power and it moves normally, except that it is 2 minutes behind. Apply the sync signal (for 25 seconds in my case) and the clock hands move fast to the next hour.&nbsp;<br /> <br /> I hope this helps<br />
Ok, I'm not sure if you''ll know much about this but I though I mite as well ask. <br /> <br /> On a radio controlled clock mechanism, when the battery is inserted, the clock turns to 12. It then stops and waits for the correct signal. If the signal is recieved, the clock turns to the correct time. If the signal is not recieved, the clock starts operating as a quarts mechanism from 12. <br /> <br /> Do you know is there any way we could make the clock work as a quarts movement without waiting for the signal?<br /> <br /> Thanks Niamh<br />
I don't know much about radio-controlled clocks. <br /> Maybe if you take one apart it would be clearer.&nbsp;<br /> <br /> Regular quartz clocks can be manipulated. They have a simple&nbsp;<br /> motor that takes (~1.5V) pulses of alternating polarity, one short&nbsp;<br /> pulse per second. If you generate these pulses (say with an Arduino)&nbsp;<br /> they can be slower or faster in any way you wish. If you stop the pulses,&nbsp;<br /> the clock will stop. If you send 10 pulses every second, the clock will&nbsp;<br /> move 10x as fast, the second hand moving around the dial in 6 seconds!<br /> It is tricky and unreliable to make it go backwards, as the direction is&nbsp;<br /> designed into the metal parts of the motor (people make clocks that go backwards by flipping this piece of metal).&nbsp;<br /> <br /> Anyway, If you use this idea, the clock (especially the second hand)&nbsp;<br /> will move quickly as you &quot;catch up&quot; to real time. Using electronics&nbsp;<br /> to generate the pulses allows for a lot of flexibility.&nbsp;<br /> <br /> Let me know if I need to explain more.&nbsp;<br /> Good luck!<br />
&nbsp;To me it seems like the jar file is broken. I am unable to download it. Your file would be perfect to experiment with since I have often dreamed of getting a java program to interface with my arduino.&nbsp;
&nbsp;Apparently Instructables renames the files to &quot;something-weird.tmp&quot;<br /> Just change the name of the file you download to what it is supposed&nbsp;<br /> to be, and it should work. Let me know if there is a problem. It should&nbsp;<br /> definitely work on Mac OS X (it may not find the right port on Windows).&nbsp;<br /> <br /> I'll see if I can get you the source code somehow, that would probably&nbsp;<br /> be more useful for you.&nbsp;<br /> <br /> The easiest communication is just by using the serial console in the&nbsp;<br /> Arduino IDE. That's a good place to start.&nbsp;<br />
I wonder if this system could be used in a smaller scale, and without the slave clocks.<br /> <br /> 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.<br /> <br /> What I&nbsp;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.<br /> <br /> Obviously this doesn't need slave clocks, it just needs to operate a relay switch to take over for the manual buzzer buttons.<br />
&nbsp;Yes, this should be simple enough. You do not have to connect the slave clocks. You do not have to connect the bells. You do not have to connect the LCD. It's mix and match!&nbsp;<br /> <br /> Right now the bells only go off Monday-Friday, and the duration is always the same (but adjustable). Right now there are two bell &quot;zones&quot;, but it shouldn't be very hard to add one more (need to change the Java controller software a little though).&nbsp;<br /> <br /> Let me know if you need more help.<br />
Oh man. I wish I had this Instructable when I was in high school. I can think of some mighty fun ways to use this knowledge to get expelled.<br /> <br /> Great Instructable.
Yes, there are some fascinating possibilities! There is a good reason no Ethernet shield is used for this project even though that would have allowed for an automatically setting clock (using internet time servers). Some fully-featured master clocks for sale do have this feature...<br /> <br /> Thanks!<br />
My spanish teacher currently does not have a clock in his class, so it's annoying for everyone who wants to know what time it is. He's trying to get a new clock, but the beauracratic system is insanely slow, and him getting a clock is a low priority. The clocks that are in other classrooms look like the clock you took a picture of, and there are 4 (I think)&nbsp;wires that would go into the clock. Could you possibly give me some information on how to make a slave clock? I am very good with technology (I built a <a href="http://makerbot.com" rel="nofollow">MakerBot</a>, <a href="http://picasaweb.google.com/cyrozap/MakerBot000117Spartan?feat=directlink" rel="nofollow">#000117</a>) and have an arduino, so this should be a piece of cake.<br /> <br /> Maybe it could have 4 large 7-segment diplays made by using 1 led each and diffusing plastic. I have the LEDs on hand.<br />
The easiest solution and most low-tech, but also the least fun, is just to go to Stapes (or whatever) and get a large battery-operated clock to hang on the wall. <br /> <br /> If the classroom has the wires already, then you could attempt to build a slave-clock. Beware that the wires could be 120V AC. The slave-clocks in the school where I installed this master-clock run on 24V AC. There are three wires for the clock, hot, neutral, and synchronization. There are a couple of other wires for the PA system housed in the same cabinet (also used for the bell signals). <br /> <br /> The protocol for &quot;my&quot; slave clocks is that the sync wire goes hot on the hour for 25 seconds, except at 6 am and pm, where the signal lasts 25 minutes. To build a slave-clock, you just need a &quot;regular&quot; arduino clock, with some sort of connection from the sync wire to an arduino input. A diode and then two resistors (say 10K and 1K) with a capacitor (say 10 microF) in parallel. The Arduino ground goes to the neutral wire, and the Arduino input senses the voltage over the 1K resistor (this is assuming 24V AC on the sync). The Arduino input can only handle up to 5V (DC of course). <br /> <br /> You add some code to a basic clock that senses when the sync signal goes on, and when it goes off the clock should display either X:00:25 or 06:25:00 depending on the length of the sync signal and the time (X) when the sync signal started. Thus if your clock is a little slow or a little fast, it can adjust on every sync. <br /> <br /> Good luck! And if you are building a slave-clock, feel free to ask more questions.<br />
&nbsp;oh that happend at are school every 5 minutes it went into &quot;time travel mode&quot;
Just out of curiosity (since it is unlikely I'll get a chance to do this) - <br /> *&nbsp;How do you interface the master clock to the other (slave) clocks?&nbsp;What kind of signal do they expect? Are they wired or wireless?<br /> *&nbsp;Is the clock protocol openly available?&nbsp;(The manufacturer you mentioned doesn't appear to disclose anything)<br />
The slave-clocks are wired. There is one wire that carries the synchronization signal, 25 seconds on the hour every hour, except at 6 (am and pm) where it is 25 minutes (12 hour sync). There are other protocols. <br /> <br /> Even though the manufacturers themselves do not disclose the protocols, they can be found on the internet. <br />

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