PreamplifierCircuit DCF77


Posted on Feb 5, 2014

DCF77 Preamplifier Circuit DiagramA popular project among microcontroller aficionados is to build a radio-controlled clock. Tiny receiver boards are available, with a pre-adjusted ferrite antenna, that receive and demodulate the DCF77 time signal broadcast from Mainf lingen in Germany. DCF77 has a range of about 1, 000 miles. All the microcontrolle


 PreamplifierCircuit DCF77
Click here to download the full size of the above Circuit.

r need do is decode the signal and output the results on a display. The reception quality achieved by these ready-made boards tends to be proportional to their price. In areas of marginal reception a higher quality receiver is needed, and a small selective preamplifier stage will usually improve the situation further. The original ferrite antenna is desoldered from the receiver module and connected to the input of the preamplifier. This input consists of a source follower (T1) which has very little damping effect on the resonant circuit. A bipolar transistor (T2) provides a gain of around 5 dB. The output signal is coupled to the antenna input of the DCF77 module via a transformer. DCF77 Preamplifier Circuit Diagram The secondary of the transformer, in conjunction with capacitors C4 and C5, forms a resonant circuit which must be adjusted so that it is centered on the carrier frequency. An oscilloscope is needed for this adjustment, and a signal generator, set to generate a 77. 5 kHz sine wave, is also very useful. This signal is fed, at an amplitude of a few milli-volts, into the antenna input. With the oscilloscope connected across C4 and C5 to monitor the signal on the output resonant circuit, trimmer C5 is adjusted until maximum amplitude is observed. It is essential that the transformer used is suitable for constructing a resonant circuit at the carrier frequency. Our proto-type used a FT50-77 core from Amidon on which...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Car Parking helper
    Function-generator
    Ultrasonic-receiver
    Current Loop
    Precision Audio Generator For Musical Instrument Tune-Up Circuit
    200mW High Quality FM Transmitter With TX-200
    CSC231 Homework
    All 7-pin Tube Based Phonostage
    schematics Buck switching regulator based on ATtiny84a -- please critique!
    Wireless controlled Door-bell
    TNT1541 diy zero-oversampling dac
    LF356 composed of AD converter
    Single nozzle tracker circuit diagram
    YSS247 application circuit



    Top