A recent discussion on electric clocks, started by a spammer but turned into a proper discussion by some of our regulars, prompted me to rekindling my interest in electric clocks.

I've always like Smiths clocks and remember seeing them in the classrooms of the schools I went to - a time when electric clocks, fitted with mechanisms powered by a synchronous motor, were the preferred option as they don't lose or gain time when in good working order.

In the last week or so I have purchased three preloved electric clocks and have restored the first one tonight as a practice run. It is a Smiths Sectric Bakelite clock, no doubt intended for the kitchen because of its bright colour. This model (pictured) comes in numerous colours, amongst them; white, cream, green, blue, red, mint and walnut. There could also be other colours though these are the ones I've seen.

This one will hang in my kitchen once I install a new flex and a clockpoint plug on it.

My question is, is there enough interest amongst members here for a forum relating to vintage clocks?

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A valve a day keeps the transistor away...

I understand that it used to be a function of the grid system control to finesse the system frequency in the early hours to keep synchronous motor clocks on time. I wonder if this still happens in these days of crystal controlled time pieces.

If there are any doubts about the thread, a post on a clock-radio would settle the issue. I've got a Hanimex flip-clock that was bought at K Mart in the sixties when I went on shift work. Slowed down when the motor bearings dried out. Replaced an open circuit transformer. Retired it after it slowed down after the third motor oiling.

I've got a cheap Chinese Goldair CR909 digital green digits AM/FM clock radio that I bought as an emergency measure at the local pharmacy in 1988 and it's still going strong.

I was only thinking a few days ago how it's lasted much longer than I would have expected. I don't know what technology the display uses but it hasn't faded or lost any digits -- so far.

I've grown quite fond of old reliable.

That green display is a valve and they are still in use today in HiFi gear. If you look very closely you'll see two heating elements going across the display and the number segments have a coating of phosphor.

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A valve a day keeps the transistor away...

This is a clock radio!
It is a Goblin Time Spot, made in England and is one of my recent restorations. The radio was quite straight forward to get running but the clock was a challenge. It is a synchronous movement, relying on the accuracy of the 50 Hz mains frequency for time keeping, as noted in an earlier post.
Harold

"That green display is a valve and they are still in use today in HiFi gear. If you look very closely you'll see two heating elements going across the display and the number segments have a coating of phosphor."

If it's a VFD it's probably alive because it's a clock,
and the digits change so that segments aren't left on days at a time.

So far nothing looks better, and I think that's the only reason they are still around:
http://www.noritake-elec.com

I can't use them because you can't leave any static display on them
(at leas the ones they make now), and expect them not to dim.
I tried to cheat that:
http://www.youtube.com/watch?v=lpduqsea5Kk
It's obvious why it didn't make any difference to significant digits!
You would have to move the clock display across the screen.

So if the 50cycle standard is important to things like the scan rates of CRTs and the spin rate of audio turntables, how would it not be reliable enough for a synchronous clock?

Apart from blackouts, the only thing I can think of is if spikes or brownouts caused the synchronous motor to miss the odd phase, and these glitches could accumulate over a period to lose some time.

Is there ever significant variation in the frequency of mains supply? Just curious.

As an aside, I have noticed that modern mass-market electronic clocks will drift away and need correction every now and then. Not sure if these are actually "crystal" controlled, or just using IC counters with a capacitor resonator for timing control. Capacitors will rarely be absolutely on spec.

As to "old and reliable", my general observation is that the higher the degree of electronic integration, the lower the reliability and higher the likelihood for total failure from a single fault.

Maven

I termed my 1988 clock "old reliable" because it's both. I haven't pulled it apart to see how it's made, nor will I lest I let the Genie out.

Where low end consumer grade goods are concerned, I'd agree with your point about reliability and single point of failure.

Gandhn "This is a clock radio!"

You said it!

Beautiful piece. One I'd love to own myself.

I doubt they are using the mains freq anymore for timing Maven.
In digital clocks it was done with the secondary of the mains transformer.
Then you already have a 50Hz pulse.
This was convenient because the transformer is in the same
case as the clock chip, and doesn't cost anything because
the mains AC had to be rectified for the clock chip anyway.

Now I think it would be just as cheap and easy to use the 32.xxx crystal.

They still drift over a year either way.