I bought a cool Transformer clock for my 8 year old from England. It operates on 9v 50 hz. I would like to build or buy a converter that will convert 120volt 60hz to 9volt 50 hz.

Can anyone direct me to a set of schematics, plans, or store that could help me?

 

It depends weather the clock derives it timesignal from the mains frequency or from a crystal.

In case of the crystal, simply buy a 120 Vac / 9 Vac 60 Hz plugpack to run your clock from.

If it is taken from the 50 Hz mains you probably out of luck and the clock will be running 20 % fast at 60 Hz.

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Electricity, Electric clocks, Meters and Trains are great.

 

For larger equipment (at a machine tool mfr) we used to have motor-generator sets that ran off our 60 Hz power and delivered 50 Hz. Some of those were quite small - but still clearly overkill for your situation. Equally "overkill" - a variable frequency AC drive - it would do the job but not worth the effort.

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stevez

 

There is one way to do this that i can see, although to be honest it's going to be a lot cheaper to get a different clock.

Get a 12V DC PSU that the input is 110V? ( i assume) AC 60 hz as would be sold to anyone wanting to run 12V dc equipment off the mains power supply in USA.
Then take that 12V DC output and connect it into a 12V inverter (BRITISH ) this will have the necessary 50hz output but at 230V AC
then connect the output of this to a step down transformer to give you the 9V ac that you require. OR if the clock already runs from 230V AC 50 hz you wont need the 9V transformer

 

The suggestions are getting silly!

For a start you need to find out if it uses the incoming frequency for the clock timing - a simple and easy (but crude) test would be to try feeding it from a 9V battery, it 'might' work perfectly well like that!.

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I was rushing when I offered the first reply though I do recall seeing very small surplus motor-generator sets. What I don't know much about - the waveform provided by an inverter and whether or not the frequency is such that you can depend on it. All of that presumes that the motor is synchronous - hopefully RODALCO's thought about the crystal is correct - don't see many "motor" driven clocks any more but that doesn't mean they aren't out there.

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stevez

 

Is it based on a standard LED digital clock, such as this?:
http://www.shinyshack.com/product.ph...on-Alarm-Clock

It may possibly use a standard clock chip such as an LM8560 which has a 50/60Hz selection jumper pin.
http://www.alldatasheet.com/datashee...YO/LM8560.html

Perhaps it has some other type of clock chip that can auto-detect the frequency?

If it just has a resin "blob" chip with no selection jumper or auto-detection of mains frequency etc. then you could be out of luck.

 

An alterative could be to attach a frequency generator (PIC ,8051,AVR) to the sense lead, the clocks usually have a seperate input for line frequency measurement.

 

To get 50 Hz with the same accuracy as the power line, you could use a PLL. Rectify the 9V 60 Hz, and also feed the 60 Hz to a divide by 6 circuit. Feed this 10 Hz into one input of a 4046 PLL phase detector. Set up the timing capacitor on the 4046 so its center frequency is 100 Hz. Take the PLL's 100 Hz, divide it by 10 and feed it to the other input of the phase detector. Use phase comparator II. Make your loop filter greater than 1 second. Take the 100 Hz VCO output, divide it by 2 (to assure symmetry) and drive a low-power h-bridge, and pass it on to the clock. It probably won't mind a square wave.

If you do this all in old fashioned CMOS, it may not need level translators. (But use good static handling procedures).

 

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