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Old 7th Mar 2008, 2:42 pm   #1
350i
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Default Master Clock Substitute?

Hi all
I just wondered, after seeing some nice slave-clocks for sale over the years, if there was something you could buy (or make yourself) which would send the low voltage pulses and take the place of the master-clock?
Thanks
Trevor
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Old 7th Mar 2008, 3:24 pm   #2
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Default Re: Master Clock Substitute?

The good folk at ELEKTOR thought this too - They published an article some years back - It used a 4 transistor "bridge" to generate the alternate pos and neg pulses every 30 secs. I modified it to give 1 second pulses and then connected it to 2 cheap battery clocks, using just the "drive" sectionof each clock. It worked quite well synched from the mains, but you will need something more accurate as a ref standard oscillator as the mains is not always spot on !
I'll see if I still have the article, or ELEKTOR'S website may be worth a try
Andy
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Old 7th Mar 2008, 4:12 pm   #3
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Default Re: Master Clock Substitute?

Never tried it, but a cheap quartz battery clock movement makes an extremely accurate source of pulses at 1s intervals.

I'm sure you could run a pair of wires from the impulse electromagnet and feed the signal to the slave via some kind of simplish interface (maybe with a divider if nec.).

Nick.
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Old 7th Mar 2008, 5:03 pm   #4
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Default Re: Master Clock Substitute?

Hi,

The answer is yes...

The best way of doing it is to use the 50Hz mains frequency and simply divide it by 10 and 5 to get the 1Hz.
Or to use a 32KHz watch crystal ad divide from that.
You can do this with (dare I say) a couple of CMOS IC's (not vintage sorry) well they could almost be, the way things are going.
If you would like more details, I could help you with this.

Daniel.
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Old 7th Mar 2008, 6:18 pm   #5
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Default Re: Master Clock Substitute?

Such things are for sale, at a price! I cannot understand why anyone would buy one; a 99p quartz clock with a seconds hand and either two reed switches or an optocoupler plus a few junkbox bits would be fine.

Or a cheap synchronous mains timepiece to do the same?

However, a real master clock is much more interesting than a few impulse dials (commonly, but erroneously, called slave clocks).
I made one in 1987.

Most impulse dials give 30s pulse intervals and require about 1.5v and maybe 300mA. Polarity is not important.
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Old 7th Mar 2008, 9:14 pm   #6
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Default Re: Master Clock Substitute?

Hi!

Is this any good - Elektor's Circuit ready for plugging into Eagle......!!!

Chris Williams
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File Type: zip Clock Controller.zip (207.9 KB, 283 views)
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Old 7th Mar 2008, 10:47 pm   #7
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Default Re: Master Clock Substitute?

This is well worth a look.

http://uk.geocities.com/brettoliver@..._electronic_1a

Must say, I'm very impressed indeed by this and will have a go at building one myself one day. I do possess a few old master clocks though and find them infinitely more interesting than any electronic alternative.
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Old 8th Mar 2008, 12:16 am   #8
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Default Re: Master Clock Substitute?

Ah, that was the site I was looking for!
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Old 8th Mar 2008, 11:18 am   #9
Kat Manton
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Default Re: Master Clock Substitute?

Hi,

I haven't got a slave clock but if I had, I'd arrange to generate the pulses from one of the computers here, probably our main server.

One of the machines here is synchronised via Network Time Protocol to three of the United Kingdom zone NTP pool servers and the rest of the machines are synchronised to that machine.

Given I already have at least one computer running 24/7 with its clock not far removed from a time standard somewhere, it'd be ideal for synchronising a slave clock.

This thread has got me thinking now; it'd be good to have a nice-looking clock or two around the place, showing accurate time...

Cheers, Kat
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Old 8th Mar 2008, 1:45 pm   #10
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Default Re: Master Clock Substitute?

About 12 years ago I acquired a brand new Microquartz 6 master clock which was being thrown out at work as it wasn't compliant with the then new EMC regulations and couldn't be sold. It's a microprocessor controlled clock with an output for synchonising slave clocks in several different formats and can also be connected to a DCF radio receiver for accurate time.

From the manual it looks as if the slaves can be controlled by pulses every minute, 30s or hour at either 24v or mains.

It doesn't look as impressive as the pendulum master clock in the engineering building at university. This had a few problems as the slave clocks were in a complex series parallel combination and when the clock batteries were low some slaves stopped working resuming operation when the batteries were recharged. This lead to each slave clock having its own time zone and two clocks in one of the lecture theatres showing different times.

Keith
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Old 8th Mar 2008, 1:59 pm   #11
Chris55000
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Default Re: Master Clock Substitute?

Hi!

I'm poring over the plans from the Geocities site now! I was going to make Elektor's circuit but this one's much better!

Chris Williams

PS! Rotten yahoo keep blocking access to it!!!

Last edited by Chris55000; 8th Mar 2008 at 2:16 pm.
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Old 8th Mar 2008, 3:02 pm   #12
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Default Re: Master Clock Substitute?

I was thinking of GPS receivers, these usually have a TTL (or sometimes RS232) output that could be converted to a usable clock pulse.
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Old 8th Mar 2008, 7:45 pm   #13
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Default Re: Master Clock Substitute?

Setsappeal said:

Quote:
It worked quite well synched from the mains, but you will need something more accurate as a ref standard oscillator as the mains is not always spot on !
This is quite right, the frequency does drift a bit, so it's not so good as a standard frequency oscillator.

However, the CEGB does monitor frequency, and over a 24 hour period they manage to speed up or slow down the whole country's generators to make the total number of cycles extraordinarily accurate. So, at any instant, a mains-derived clock may be a few seconds fast or slow, but it won't cumulatively gain or lose time.
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Old 8th Mar 2008, 8:32 pm   #14
Dave Moll
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Default Re: Master Clock Substitute?

This is borne out by my two VCRs. The reasonably modern VHS machine displays a time maintained from broadcast information, whereas the much older Betamax machine has a time display presumably synchronised to the mains. They are never more than 30 seconds apart (and usually much less), but either one can be ahead or behind at any given time.
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Old 9th Mar 2008, 12:36 am   #15
350i
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Default Re: Master Clock Substitute?

Hi
thanks for all of the replies. My original thought was for something giving 30s impulses and compact enough to fit out of the way, the Elektor circuit looks very interesting. I must admit though, after seeing what has been available on ebay recently, I'm warming to the idea of buying a master-clock. My wife will be happy to know that after taking up our floor and shelf space with radios I'm starting to think of taking up wall space as well!
Regards
Trevor
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Old 9th Mar 2008, 9:49 am   #16
Mike Phelan
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Default Re: Master Clock Substitute?

Trevor
PM me if there is anything you spot and need advice on it - I know about such things.
Synchronome usually fetch the most money, but there are also Gents and TMC which are similar.

A sobering thought; how accurate do your domestic clocks actually need to be?
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Old 9th Mar 2008, 10:10 am   #17
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Default Re: Master Clock Substitute?

http://evingar.www.idnet.com//cpld_f...n_service.html.

If anyone is interested, I can supply one for £6, to include (UK) postage. I'll even throw in a PLCC PTH socket so it can be constructed on Veroboard / tripad (etc).

Click on the link on the linked page to download the data .PDF.
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Last edited by evingar; 9th Mar 2008 at 10:15 am.
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Old 10th Mar 2008, 4:23 pm   #18
350i
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Default Re: Master Clock Substitute?

Mike
They don't need to be particularly accurate because we have plenty of modern clocks in the house. I'm just interested in them from a collectors point of view and already have a couple of antique mechanical clocks.
Thanks for the offer of advice , I may need it when I get one!
Regards
Trevor
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Old 10th Mar 2008, 6:14 pm   #19
Mike Phelan
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Default Re: Master Clock Substitute?

Quote:
They don't need to be particularly accurate
To be honest, Trevor, I find that within 5 minutes is sufficient for most things!
It is a problem here if they all strike at the same time and someone phones me!

Quote:
because we have plenty of modern clocks in the house
Never mind
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Old 26th Mar 2008, 6:29 pm   #20
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Default Re: Master Clock Substitute?

Just seen something on eBay, which may or may not be useful. It's item # 200209452531

Nick.
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