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Digital clock

Discussion in 'General Electronics Discussion' started by Karthik rajagopal, Dec 31, 2016.

  1. Karthik rajagopal

    Karthik rajagopal

    191
    5
    May 9, 2016
    Hi all,
    I had a old digital clock along with a radio which works in 110v. I used a 220v -110v converter as the domestic power supply here is 220v. While the clock runs , for every minute it loses about 12 seconds. But when we were using it in USA we got the correct time without any loss. Why is there a delay when I connect it with the converter (220v - 110v) in India? Is there any problem with its circuit?
     
  2. duke37

    duke37

    5,253
    726
    Jan 9, 2011
    The clock probably uses the AC supply as its frequency reference. The supply in the US is 60Hz whereas I think you have 50Hz so the clock will run slow at 5/6 the rate.

    Also it is not clear what you convertor is. If it is just a transformer (likely) there is nothing you can do about it.
     
  3. Karthik rajagopal

    Karthik rajagopal

    191
    5
    May 9, 2016
    Do we have any circuit which converts 220-110v along with frequency ?
     
  4. duke37

    duke37

    5,253
    726
    Jan 9, 2011
    It can be done but is hardly worth while unless you want to do it for fun. This would be done by transforming to DC and then using a free running invertor to generate 110V 60Hz. The frequency may not be sufficiently accurate.

    One way is to make a 300Hz oscillator which is phase locked to the 6th harmonic of the 50Hz input. Then digitaly divide this by 50 to get 60Hz.
    An audio amplifier could then be used to provide sufficient power to run the radio, transformed to the appropriate voltage

    If you are capable, then it may be possible to connect the oscillator/divider inside the clock and use the original power circuit to drive the radio and clock power supply.
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
    2,694
    Jan 21, 2010
    It is also possible that the clock has an option to select 50 or 60hz internally.

    It is also possible that even if this option exists it isn't obviously switchable or even documented.
     
  6. 73's de Edd

    73's de Edd

    2,732
    1,122
    Aug 21, 2015
    Sir Karthik . . . . .


    With your given information and the time error amount given, I heartily concur with the last suggestion.
    If that units internals design is using old 1970s through 1980s design framework, I would expect a large 24 or 40 pin DIP performing the clock function .
    Examine inside of the unit and pass on to us all of the numbering I.D. On the large I.C. and I will research it for transition to 50 cycle operation, usually it's just being the utilization of 1 pin connection being wired in, instead of another on the connection being made to it .

    73's de Edd
     
    Last edited by a moderator: Dec 31, 2016
  7. Karthik rajagopal

    Karthik rajagopal

    191
    5
    May 9, 2016
    Thank you all for the reply.
     
  8. Karthik rajagopal

    Karthik rajagopal

    191
    5
    May 9, 2016
    That radio was bought in the year 1997. I will give you the information if I open it because I opened it once to replace the button while I noticed the switches and other components lead rusted. I will try to get the information without any damage so that I will able to rectify the mistake in that without any problem. If it is going to be a difficult task, I will go to a new one rather than struggling with this.
     
    Last edited by a moderator: Dec 31, 2016
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