Is the DCF 77,5 kHz radio signal too far away and your radiocontrolled clock gets out of sync? No problem ... here is an already tried and prove functional, old schematics. The complete schematics and explanations are here https://www.eeweb.com/dcf77-preamplifier/
The tranzistors and the ferrite ring are cheap and worth bought exactly as indicated. Very few tests are needed. The entire device fits inside the clock and can be powered from the same battery (6V in my case), and the amps is less then 1 mA. However, after many testes I chose to take out the internal DCF decoder and add some CAT5 cables (about 3 metres) and that gave me excellent results. The preamp was connected nearby the DCF module, all externally.
The tranzistors and the ferrite ring are cheap and worth bought exactly as indicated. Very few tests are needed. The entire device fits inside the clock and can be powered from the same battery (6V in my case), and the amps is less then 1 mA. However, after many testes I chose to take out the internal DCF decoder and add some CAT5 cables (about 3 metres) and that gave me excellent results. The preamp was connected nearby the DCF module, all externally.
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Another approach, is even better if the signal is very very weak. Obviously you do not want to always move the watch from one place to another and press the buttons for regaining sync. Here is step by step:
1) Take of the LC and DCF77 module from the watch and place them near a window where the signal is strong.
2) Take a CAT5 cable and connect 4 colored wires to each of the 4 terminals of the DCF module and the the remaining 4 whiteish wires blend them together but do not connecte them anywhere
3) The other side of the CAT5 cable connect it to the internal 4 wires band cable of the watch (each terminal must be noted exactly not to connect them in the wrong way).
4) The remaining witeish 4 wires from the 8 CAT5 cable (actually 4 pairs) blend them together, and connect them with the watch ground (-6Vdc).
5) The connecting point of the -6Vdc connect it now with another wire to an earth ground, from your home such as a water metal pipe, a gas metal pipe or enything which you know it does have an earth ground connection. The phtotos are selfexplainable ... so, this method is doing just adding an earth ground in order to facilitate the better reception of the signal, through a longer data cable, a very cheap internet CAT5 normal cable, nothing special.
But this method can be associated with the above one, adding a preamplifier, if necessary. In my case, the preamplifier (without the earth ground wire) is not working so good, but when I added the earth ground wire, the signal was so strong that I only used the internal original watch DCF module, without preamp.
PROBLEM SOLVED 100%.
1) Take of the LC and DCF77 module from the watch and place them near a window where the signal is strong.
2) Take a CAT5 cable and connect 4 colored wires to each of the 4 terminals of the DCF module and the the remaining 4 whiteish wires blend them together but do not connecte them anywhere
3) The other side of the CAT5 cable connect it to the internal 4 wires band cable of the watch (each terminal must be noted exactly not to connect them in the wrong way).
4) The remaining witeish 4 wires from the 8 CAT5 cable (actually 4 pairs) blend them together, and connect them with the watch ground (-6Vdc).
5) The connecting point of the -6Vdc connect it now with another wire to an earth ground, from your home such as a water metal pipe, a gas metal pipe or enything which you know it does have an earth ground connection. The phtotos are selfexplainable ... so, this method is doing just adding an earth ground in order to facilitate the better reception of the signal, through a longer data cable, a very cheap internet CAT5 normal cable, nothing special.
But this method can be associated with the above one, adding a preamplifier, if necessary. In my case, the preamplifier (without the earth ground wire) is not working so good, but when I added the earth ground wire, the signal was so strong that I only used the internal original watch DCF module, without preamp.
PROBLEM SOLVED 100%.
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06 ceas cu impamantare IMG_20231203_211018 copy.jpg -
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01 ceas cu impamantare IMG_20231203_211143 copy.jpg
Adding the preamplifier with a hidden framed wired supplemental antenna. I have observed that after few days of testing, both the above methods need to be implemented in order to get the needed DCF signal for the watch. So, here are some photos with the complete installation. This was the best simple solution from what I ever seen all over the internet. No special complicated antennas, no complex circuits, no coaxial cables and everything it can be powered directly from the watch, which I am about to do very soon after few days of testing. The signal was strong for more than 36 hours and the good news is that it really works fine with these modifications.
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antena suplimentara tip cadru 2,8 metri IMG_20231204_090437.jpg -
antena suplimentara tip cadru 2,8 metri IMG_20231204_090448 copy.jpg -
antena suplimentara tip cadru 2,8 metri IMG_20231204_090502 copy.jpg -
antena suplimentara tip cadru 2,8 metri IMG_20231204_090510 copy.jpg -
antena suplimentara tip cadru 2,8 metri IMG_20231204_090516 copy.jpg -
antena suplimentara tip cadru 2,8 metri IMG_20231204_090528 copy.jpg
How far are you from the DCF77 transmitter, that is in Mainflingen, Germany? I am at 875 km and don't have any reception issue in-house. I suppose the good reception is about up to 1200...1300 km.