Summary of A combined MSF/DCF atomic clock receiver
This article describes a DIY project comparing MSF and DCF atomic clock signals using two modified radio clock modules from Lidl. By swapping crystals, one module receives the UK's 60kHz MSF signal while the other retains the German 77.5kHz DCF signal. The circuit uses a 3.3V zener diode for regulation and includes logic gates to invert outputs. A custom BASIC V program visualizes the synchronized signals, highlighting timing differences like minute markers and leap second indicators.
Parts used in the Combined MSF DCF Atomic Clock Receiver:
- Two radio clock modules from Lidl
- 77.5kHz crystal (original)
- 60kHz crystal (replacement)
- 3.3V zener diode
- 5V power supply
- Ferrite rod antennas
- Four links for signal inversion
- PCB with four groups of NOT gates
- Seven 4000 series NAND chips wired as NOT gates
For this to work you must obviously live in an area that can receive both signals. My circuit is based on two modules taken from two radio clocks bought at Lidl’s supermarket. Originally both were for the DCF clock but by substituting the original 77.5kHz crystal with a 60kHz crystal, one of the modules was converted to MSF.
Notice that both antennas are lined up in my photograph. This is because Anthorn and Mainflingen – as seen from Limavady – are roughly in the same direction. The alignment of the ferrite rods obviously has to be adapted to your location.
Circuit description
I found that the circuit worked extremely well and reception is near perfect under most conditions.
The program
I have written a simple little single tasking graphics program which plots the output of both clocks one over the other. The MSF clock is yellow, the DCF clock is green. On the right is a small section of the output.
Not much can be learned. The most interesting bits are the beginning of minute markers. This is a half second ON for the MSF clock and a full second OFF for the DCF clock. Notice also the double pulse in first DCF second indicating a 100ms difference between atomic time and GMT. This used to be 400ms not all that long ago.
I have highlighted the interesting bits. Anything you see in red was not produced by my program but inserted via !Draw.
Here is a link to a zip file containing the draw file of the pcb layout, the circuit diagram and the BASIC V program below.
Version 2 of the program allows you to plot continuously or screen after screen. You can also change the time base.
For more detail: A combined MSF DCF atomic clock receiver
- How can I convert a DCF receiver module to MSF?
Substitute the original 77.5kHz crystal with a 60kHz crystal. - What is the required supply voltage for the circuit?
The supply voltage is 5V. - How do I adjust the antenna alignment?
Align the ferrite rods based on your specific location relative to the signal sources. - What does the yellow line represent in the program output?
The yellow line represents the output of the MSF clock. - What does the green line represent in the program output?
The green line represents the output of the DCF clock. - How long is the ON pulse for the MSF clock at the start of a minute?
The MSF clock has a half-second ON pulse at the beginning of the minute marker. - How long is the OFF pulse for the DCF clock at the start of a minute?
The DCF clock has a full second OFF pulse at the beginning of the minute marker. - What indicates the difference between atomic time and GMT in the DCF signal?
A double pulse in the first DCF second indicates the time difference. - Can the program plot continuously or screen by screen?
Version 2 of the program allows plotting continuously or screen after screen.
