I recently purchased an old school clock from a show but didn't realize it is suppose to be hooked up with a master clock to run properly. When plugged in the clock works but there is no way to adjust the time on it. There is a single extra wire which I am under the impression is to go to the Master clock to adjust the time. To my understanding the Master either tells this clock to stop (if it is fast) or to speed up (if it is slow) through this wire. However, I can't seem to find any information and how this is transmitted through the single wire.

Is anyone aware of what voltage needs to be applied to this wire in order to get it to speed up and stop?

Your help is appreciated.

-Steve

 

With the clock unplugged, it will be accurate twice a day. Wait for one of those moments and plug it in again. Piece of cake.

 

This type of clock often works by receiving a low current impulse at a fixed interval - typically once every 30 seconds. This site: http://www.hvtesla.com/masters/index.html illustrates typical examples of master/slave clock arrangements.
By wiring the slave clocks in series, it is possible to drive any number of slaves from one master clock impulse generator.

Although they were usually electronmechanical in operation, you can recreate a 'master clock' using an electronic crystal oscillator and divider, driving an external relay or solid state current sink devices, which is designed to provide a (typical) 200mA pulse every 30 seconds.

I fitted one to an old bowling club clock 'slave', a while back. (Video of the installation here: http://www.vimeo.com/1084861 if you're interested)

If that's the kind of thing you're looking at, I'll try and find the circuit if it's likely to be of any use?

 

rogs - thanks very much for the reply. If its not hiding too far I'd love to take a look at the circuit used.

This is a classic analogue North American school clock which would be one of many slaves all connected to the single master. I believe these were only time corrected once an hour or maybe even once a day (I remember being in class and seeing the needle stop... those were the worst minutes!). It doesn't need anything applied to it in order to tick along. Does the one your referring to require a impulse every 30 seconds to keep it going?

I'm still a little confused on exactly what signal needs to be applied in order to get the clock to stop/speed up.

Again, thanks for your help.

Jaguarjoe - thanks for the offer but I'd thought about that one Just not as fun, and these were somewhat notorious for not holding the most accurate time as they would need to be corrected to the master quite regularly.

 

As I recall, there were three wires going to these clocks. One line was common, another line received pulses once per minute UNTIL one minute before the hour. A clock that was accurate switched over to the third line internally. Clocks that were slow stayed on the normal 1 pulse per minute line. When the master reached the 1 minute before the hour point, the normal 1 pulse per minute line went into high gear putting out a long series of pulses. A slow clock would advance to the 59 minute point, at which time it would internally disconnect that line. The remaining line would pulse once at the proper minute point to move all accurate clocks to the even hour point. I don't remember exactly how many make-up pulses were supplied during the one minute period but it wasn't enough to make up a major error in one go. Hope this makes sense.

Check out page 5 of http://www.ats-usa.com/pdf_apnotes/MCMODES.pdf

 

Just correcting BillB's link:
http://www.ats-usa.com/pdf_apnotes/MCMODES.pdf

 

Does the one your referring to require a impulse every 30 seconds to keep it going?

I'm still a little confused on exactly what signal needs to be applied in order to get the clock to stop/speed up.

Yes, the type I'm referring to simply neds to receive a short 'pulse' every 30 seconds, to energise the slave clock solenoid, and advance the clock face one half minute postion.

To set and correct the clock, you have to manually stop and/or advance it as required.

I'm attaching a copy of the circuit I used for the clock in the video I linked to -- which is a Synchronome clock. It's accurate to about a second a day, using a standard commercial crystal, with no temperature compensation.
Not that accurate by today's standards of course, but more accurate than the original electromechanical mehanism!

Not as sophisticated as the type BillB3857 refers to of course, but here in the UK impulse clocks were widely found in industrial, educational and public locations. The one I added the driver to was installed in 1927!

I say 'added', because I left the beautiful original mechanism as it was -even though it doesn't work!!

 

I very much appreciate the help everyone.

BillB, I believe that is the exact situation I am in. So my next issue I guess is how to replicate this Master clock. I don't need to have it automatically set every hour but I'm thinking more of a dial where it either lets it run freely, stops or speeds it up.

The note mentions an AC voltage needs to be applied to clock correction coil, however it doesn't give the details about this AC voltage and what signals do what to the clock correction coil.

rogs - thanks for digging that up for me, I'm sure it will come in handy. It seems like though that clock is a little bit more sophisticated than what I need to get going.

Thanks.

 

If you want to use a single once or twice per minute pulse (depends upon the clock), just tie both of the signal lines together. The clock would need to be set manually, of course, possibly by a simple push button to simply add pulses as needed. We had a problem in one of our engineering labs where one clock failed internally and shorted the signal lines together. It really messed up all the clocks in the building. Our answer was to install diodes on each signal line at each clock to prevent backfeed from any failed clock.

 

We had a problem in one of our engineering labs where one clock failed internally and shorted the signal lines together. It really messed up all the clocks in the building. Our answer was to install diodes on each signal line at each clock to prevent backfeed from any failed clock.

That problem is of course reversed for the type of clock I'm working with. All the clocks, master and slaves are wired in series, with adjustments made to the supply voltage of the 'pulse' generator, to allow sufficient current to flow in what could be dozens of slaves, all connected in series. Problem there is not short circuits, but open circuit solenoids. One open circuit slave solenoid stops all the clocks!!
The system does have the advantage of being able to operate in the event of a power outtage, with only minimal power required from battery support supply.

Providing all the clocks are set to show the same time initally, it's a pretty robust system. All clocks will always show the same time as the master, without any remote corrections required.

Keeping the masters accurate, using electromechanical pendulums, was quite a challenge, but the history shows some pretty ingenious solutions to those problems.

Not very valid these days, of course......

 

If you want to use a single once or twice per minute pulse (depends upon the clock), just tie both of the signal lines together. The clock would need to be set manually, of course, possibly by a simple push button to simply add pulses as needed. We had a problem in one of our engineering labs where one clock failed internally and shorted the signal lines together. It really messed up all the clocks in the building. Our answer was to install diodes on each signal line at each clock to prevent backfeed from any failed clock.

When you talk about pulses what do you mean exactly? Is there a select frequency/voltage? And what creates the difference between stopping and speeding up? Sorry for the noob questions. I claim not to be slow, but sometimes feel like it! Thanks again!

edit: So it looks like there is a solenoid or magnet of some sort inside which has 1 wire connected to the live wire from the wall socket and the other side is connected to this extra wire I have. I'm guess then turning this on would speed up the clock? But how to stop it? Does this mean its activated by a pulse of like 12/15VDC?

 

The 'frequency' of the pulse will be once every 30 or 60 seconds, depending, as Bill says, on the clock.
The 'voltage' will depend on the current requirement of the clock solenoid. If it has a DC resistance of say, 100R, and needs a current of 100mA to activate, then you're going to need a DC supply of 10volts, that can supply 100mA.

The 'length' or duration of the pulse will either be specified by the clock maker, or you'll have to find out by trial and error. On the circuit I sketched, I included a variable resistor, to allow changing the pulse length of the trigger monostable. 200mS might be a good starting point.

Edit: of course, I'm thinking about this from the point of view of an impulse clock, so perhap it's not quite the same requirements for 'correction' pulse generators. But the basic principles are the same, I think.

Edit 2: This article : http://sound.westhost.com/clocks/alternate.html goes into some of the details for different types of clock, and the page has a link near the bottom of the page for further info on synchronous clocks.
Might have some interesting pointers towards what you need to do??

 

Thanks again for the help thus far everyone.

I have some more info about the clock in question. It is a "SIMPLEX" clock. There is a "Clutch Magnet" inside which is used to control the time. As I mentioned, the clock runs fine without using the clutch magnet, however this is used to correct the time. On the back of the clock the specs for the clutch magnet are as follows:

Clutch Magnet Volts: 115 V.A. 3 cycles: 60

So I'm assuming it is controlled via standard wall power. Since one side of the wall power is connected to the one side of the clutch magnet does it make sense that connecting the other side of the clutch magnet to 1 prong will stop it and the other prong will speed it up?

Thanks!

 

Look at page 25 of this......... http://www.simplexgrinnell.com/SiteCollectionDocuments/Time%20Systems/TimeManual_6351-400.pdf

Apparently, the clutch is used to stop the clock during correction periods. How it knows it needs correction must be built into the clock itself. I'm not familiar with the synchronous clocks.... only the impulse variety.

 

Thanks. Your support is appreciated

Looking at pg 25 it seems like the NO connection is what would be delivering the correction signal to the other side of the clutch magnet. I'm guessing this signal would be a pulse from the 120VAC line? Think it would be safe to test around to use a 100ms or so pulse from the 120V line? I really don't want to bust the clock mechanism as I don't know too much about them!

 

I'm really not sure exactly what the clutch in you clock does. From the drawing on Pg 25, it looks like it takes 110VAC, just like the regular synchronous motor running the clock. Does it dis-engage the clock motor? Reset the minute had to the 12 position? I couldn't find any description of the action, but to be honest, I really didn't read the entire document, either.

 

I tried playing with it briefly, I just want to ensure that I don't damage it.

After pulsing it twice the clock stopped. On the third time it sped up the minute hand until it stopped one minute before the hour. Once the second hand caught up to the hour it began to work normally. I think I'm going to do a little testing... since it sounds like the magnet can handle 110V I doubt I will be harming it me pulsing it like this. I'm assuming that's what the controller board would be doing anyways.

Thanks again for the help.

 

Hello,

What is the voltage for this Simplex? 110 ?

I recently purchased an old school clock from a show but didn't realize it is suppose to be hooked up with a master clock to run properly. When plugged in the clock works but there is no way to adjust the time on it. There is a single extra wire which I am under the impression is to go to the Master clock to adjust the time. To my understanding the Master either tells this clock to stop (if it is fast) or to speed up (if it is slow) through this wire. However, I can't seem to find any information and how this is transmitted through the single wire.

Is anyone aware of what voltage needs to be applied to this wire in order to get it to speed up and stop?

Your help is appreciated.

-Steve

 

I have an IBM Type:S3 56-12 School Clock
Works on 110v ac (Regular ac plug - no third wire)
Uses 3510 Hz to set time
Would like to build circuit to inject audio on ac to set time.

 

I worked for a large west coast university on fire alarm and clock / bell systems for 15 years. This was back in the day when people actually needed to look at a public clock on the wall !

The entire campus clock and bell system was synchronized from a central location from a controller synchronized from WWV.

The impulse clocks operate on 24 vdc (non filtered) and have 3 wires. A common, Hour correction, and Minute correction. A 1 second pulse on the hour control advances the clock to the next hour and a 1 second pulse on the minute control wire advances the clock 1 min. A longer pulse on the hour control set the clock to 5 hrs 59 mins.

The AC clock (Simplex) has 3 wires as well, AC common, 120Volt Line, and a clutch control line activated by a 120VAC pulse to advance the clock to the nearest hour, or with a longer pulse to set the clock to 5 hrs 59 mins.

If you take the protective cover off the back of the clock, you should be able to see how everything works.

At times, the clocks in a large building 'scatter' due to power glitches or power failures. At these times it is a lot easier to set all of the clocks to 6 and advance all of them to the correct time. If a 'scatter' occurs during a weekend or holiday, any clocks not reporting a correct time after 24 hours are in need of adjustment or replacement.

If the time happens to be for example 9:30Am, you would set the clock for 9 and let the hour correction pulse set it to the correct time at 10am.

Also when daylight savings time comes along setting the clocks back an hour requires the controller to advance all of them by 11 hours.
Setting them ahead is easier.

I never worked on the frequency controlled ones.

One way to test a synchronous clock is to hold it facing you with power applied and tilt it to your right for about 4 seconds and when the hour hand begins to move, immediately rotate the clock back to upright. The hour and minute should go to the next hour and 59 mins. If you tilt it for a longer time (10 12 secs) the clock should go to 5hr 59mins.

One impulse clock I worked on was installed in 1927 and required only a minor adjustment to get running again.