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USSR Clock

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kimbear

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Ok, I have a really nasty, orange Bakelite (or equivalent ugly plastic) Green Fluorescent display clock from the USSR. Very much like a stray dog, its beautiful in its own way, and is a great example of a utility design.
It is stamped 220v, and that voltage is easily obtained, even if I have to replace the mains transformer in it.
What Id like to know is:
-since its absolutely inaccurate at 60hz, what would the operating frequency be? (Ive tried it on 220vac and it doesn't keep particularly good time, leading me to believe it requires something other than 60hz.).
Is there a relatively easy way to "inject" its required frequency, if I did find out the frequency it likes?

..or should I just scoop out its guts, and replace it with a North American unit....a crying shame, but Ive done it before.

As per usual...thanks.

 

JimB

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DerStrom8

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I agree with JimB. Russia (USSR) uses/used 230VAC 50Hz mains. You would need an actual 50Hz mains power supply to properly drive this clock, unless you plan to completely redesign the circuitry.
 

Diver300

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So is there a way to INJECT a 50hz signal in to this, almost like a battery operated clock??
Probably.
Have a look and see if there is a signal that comes from the transformer that doesn't go through a rectifier.

The first thing to do is to run it at from 60 Hz (which I assume is what you have handy) and see if it is exactly, 20 % fast, so taking exactly 50 minutes to move on by 1 hour. If not, then the 50/60 Hz issue is not the only problem.
 

RODALCO

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USSR is 220 Volts 50 Hertz. Please put up a picture of the internal circuit board.
 

KeepItSimpleStupid

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Some ideas, are to reverse engineer the time base circuitry and work from there. The zero cross detector might be as simple as: http://www.bristolwatch.com/ele2/zero_crossing.htm

Building a square wave inverter is not that hard for low power. Making it crystal controlled might be a little harder.

Making it use 60 Hz time base and make a synced 50 Hz out of it, I'd be initially clueless except it might involve a phase locked loop..
 

dr pepper

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If there is a crystal on board (little metal can) then it might not require a certain mains freq, allthough soviet stuff tends to be done simply so it probably doesnt have an xtal.
The 50hz probably comes off a transformer, goes through squareing circuit which will convert it into logic levels and then onto either a counter chain or a uproc, you could put together a simple circuit that generates a precise 50hz waveform to drive the clock.
Probing with a 'scope wiould probably find it.
Can you post some pics?
I build weird and wacky electronic clocks with arduino's & pic's, sounds like the displays are glass tubes with 6 round fluorescent dots inside.
 
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schmitt trigger

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Please post pictures! Lots and lots of them!
I love retro electronic devices. USSR-made ones are the ultimate ones in that respect. You have a very unique unit.

To your question: I agree that it will most likely have a simple power line derived time base. Since Russia is 50 Hz, the electronic divider will run 20% faster at 60 Hz.

I would hesitate to modify such a rare unit. So....What I would do is build or buy a sinewave inverter with an output of 220v, 50 Hz. There are many low cost ones on Ebay, and you would supply it from a 60 Hz powered rectifier.
 
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spec

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The technically simple approach would be to make a little 50Hz 230V Xtal controlled inverter powered either from a battery or from your mains supply. The clock will not take much power so the inverter would be relatively easy to design and make.

spec
 

Nigel Goodwin

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The technically simple approach would be to make a little 50Hz 230V Xtal controlled inverter powered either from a battery or from your mains supply. The clock will not take much power so the inverter would be relatively easy to design and make.
Year ago I had a mains powered 2m transceiver, which had a mechanical digital clock in it.

The clock was 60Hz, but had been modified for the UK by the addition of a simple multivibrator driving a small mains transformer backwards.

Needless to say, it was wildly inaccurate, but using a crystal oscillator (as you suggested) would cure that problem.
 
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