My friend gave me a non working digital clock so he said. It works from two AA 1,5V Alkaline battery. When I took it home, I tried to use it with one of the 18650 cells since I have some now and it worked! The curiosity of this clock is that it is radio controlled. This means that it is automatically synchronized by a time code transmitted by a radio transmitter connected to an atomic clock in Mainflingen, Germany. The code of this station is DCF77. This station is 500 miles away from my home and it sends the signal 24 hours a day. It sends the exact time and date as well. The photo of the station is a bit similar to the conspiracy theories American weather controller station. But I do not believe in such things. :) The transmitted signal is repeated in every minute and each second sends its own information bits. Hour, minute, day, month, year. They do not transmit the seconds, I guess the clock automatically adjusts the time to the beginning of a minute.
It is very interesting that they also send the signal of the summer time change and the so called leap second as well. A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1. Wiki link. This is something like the leap year. Last year there was a leap second added on 30th June at midnight, when the clocks showed 23:59:60 second instead of 00. But it is sometimes added on New Year’s Eve. The wiki page worth the reading, as this leap second have caused problems for some companies before. For example at the airplane control, as a plane can move 0,16 miles in one second.
Until now there was a 14 bits unused space, in Germany they are just trying to use it for emergency information broadcast. I think this is a good idea. I just need a receiver.
The reception area around Germany:
One can buy a receiver circuit for DCF77, but they are a bit expensive.
It is fascinating that today when there are clocks everywhere and in every device, no one cares about a clock which is as accurate as an atomic clock. How much they would have respected it in the beginning of the last century! It is a bit luxury to have this and it also feels a bit strange, that the clock on the nightstand is as accurate as an atomic clock. And it is for free as well.
What I also noticed that it not always able to synchronize itself with the transmitted signal. For instance my computer's electronic radiation prevents the synchronization. If I put the clock into the window it finds the signal very fast. There is a signal power meter on the LCD, it is very convenient.
Some words about this clock. It's brand is: home by somogyi . The company: Somogyi Elektronic Kft was established in 1991 in Hungary with headquarters in Győr. They practically buying parts and products from China and they put the somogyi brand on them.
Luckily it can handle 4V Li-ion voltage well.
Its power consumption facts:
basic power consumption: 0,01mA
when it is looking for the transmitted signal: 0,29mA
if the backlight shines: 50mA (unfortunately I have broken this when I opened it and I was not able to solder the panel back)
So it consumes very little power, which is consumed by the big display.
One can set two different alarm times on it. It looks like this when opened. It was manufactured at the end of 2007, so it is older than 8 years. The big coil is required to receive the transmitted signal. There is the quartz crystal in the middle, on the right there is the tweeter. There are three chips covered with resin or something as it is cheaper than to box them.
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