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I recently bought a vintage flip-digit radio alarm clock from ebay, because I plan to refurbish it and basically use it for the rest of my life. However I only realized that the device must be connected to mains when I had already bought the thing. I was assuming it would just work on 12V like most small electronic devices, but I guess because it's from the 70's I can't live in such luxury yet.

This is the clock I'm talking about.

The alarm clock is rated for US mains, so 120V 60Hz, and requires only 8W of power. The ratings where I live (Europe) is 230V 50Hz, so I have a couple of questions that I would like to have answered. I searched the web but nothing could tell me the answer to my clock-specific questions.

  1. Can I just plug the thing in my 230V supply? Do you reckon it has an internal converter or is it really 120V only?
  2. I have found several cheap converters from US to EU power rated max. 100W, but they do not specify the frequency of the AC. Do you think these converters, which cost around $30, convert the frequency as well?
  3. Is it a problem if the frequencies don't match? Will my clock run 16.67% slower on the 50Hz AC?
  4. The clock is only 8W, so might the $30 adapter too imprecise (by lack of better words) when it outputs less than a tenth of its maximum power output?
  5. What do you recommend?

Thank you for your time and I'm looking forward to reading your responses.

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    \$\begingroup\$ Just emigrate to the US, it will probably be easier ;) \$\endgroup\$ – pericynthion Nov 2 '16 at 15:47
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    \$\begingroup\$ You know, with everything I've read on the subject so far I'm actually convinced you're right. \$\endgroup\$ – MicroParsec Nov 2 '16 at 16:32
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  1. No. The plugs & receptacles do not match, the voltage will ruin the device, & the AC frequency is likely too slow for the clock to keep proper time (even if you used a common step-down voltage adapter/converter.
  2. No. Cheap converters will likely not provide an increase from 50 Hz to 60 Hz (which is what your clock needs to keep proper time)--although, you may be able to find a pwm or switched mode power supply that will provide 60 hz output from a 50 Hz source. Definitely verify that capability before you buy an adapter/converter.
  3. Yes, it will be a problem if you want your clock to keep proper time (not that there is any guarantee that your old clock will actually keep proper time at 60 Hz ;) ). Yes, it will most likely run slower (but, it really depends on how the system was designed). If you have a cheap AC adapter/converter, then try it to see if/how much the time difference is--it won't likely be damaged by running it at 50 Hz. If the time difference is too much, then look for a better power adapter/converter.
  4. No. The 100W spec is the max power that the adapter is rated to provide. It will provide any level of power from 0-100W. If your load is only 8W, then that just means it uses less power through the adapter than the adapter is capable of providing.
  5. Search for a transformer based pwm or switched mode power supply that transforms 50Hz AC @ 230V to 60Hz AC @ 110V. Try here.
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  1. If you plug it in to 230VAC it will be destroyed, without question.

  2. They do not convert the frequency.

  3. Yes, I believe it will run slower on 50Hz. The timing motor (probably a synchronous motor) may also overheat.

  4. No the 100W converter (assuming a transformer type, which is usual at that power level) is fine for converting the voltage.

  5. Try to find an adapter specifically designed for clocks. Even if the frequency was converted it would not likely be accurate enough for a clock by default. It will not likely be particularly cheap, but your vintage clock radio is priceless, right?

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  • \$\begingroup\$ DANGIT, but thanks for the quick insight! EDIT: oh my god an 160$ clock adapter, that's three times the price of the clock... haha shoot me \$\endgroup\$ – MicroParsec Nov 2 '16 at 14:36
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It might be worthwhile taking the radio apart and examining the clock motor. There is a good possibility that it is a motor combined with a gear in one case to provide 1 RPM or 60 RPM. You might be able to find a replacement motor for 220 volts, 60 Hz with the same output speed.

You may also find that there is a transformer for the radio that can be replaced with a 220 volt, 50 Hz transformer with the same secondary voltage as the original.

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  • \$\begingroup\$ That's a great idea--and possibly less expensive than other solutions. \$\endgroup\$ – zeffur Nov 3 '16 at 2:41

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