A simple DCF77 receiver

If you can't find the specified DCF77 receiver (Conrad 19 06 91) you can try with a commercial DCF clock or alarm clock. Inside you should find two IC (a receiver and a clock chip): between these two ICs there should be a connection where the DCF signal is transferred (100 and 200 ms pulses). Some simple measurements with an oscilloscope will quickly allow you to find the right connection.
So connect this wire to pin number 2 (of the DIN3 connector) of the interface, remove the 100 kOhm resistor and the 100 nF capacitor connected to it and connect pin 1 to the receiver ground.
On pin 3 a stabilized voltage of 1.8 V is available, and can be used to power the receiver and its attached clock.
If the DCF signal is inverted on your receiver (LED stays always on and blanks off each second except for the 59th) swap pins 2 and 3 of the TL081.

The above photograph shows the Conrad receiver mounted in a plastic box with the ferrite antenna (the two capacitors are not visible since they are situated under the PCB).