Extinguishing spark transmitter
The extinguishing spark transmitter , also known as the sound spark transmitter , was a further development of the blast spark transmitter and, like it, was used to transmit Morse code signals in wireless telegraphy . It was developed by Max Wien in 1905 and was widely used in the early days of radio telegraphy, particularly in marine radio communications . It was also this type of transmitter that transmitted both the first FT emergency call in 1909 and the SOS signal of the RMS Titanic , which went down in history in 1912 .
construction
The extinguishing spark transmitter is based on the principle of exciting an electrical oscillating circuit through voltage flashovers , clocked by means of an alternating current source of z. B. 500 Hz. First, a capacitor is charged to a few kilovolts. When the minimum voltage is exceeded, the spark gap ignites and the capacitor discharges through the coil . Both together result in a series resonant circuit that transfers its energy to the antenna .
The structure of the spark gap is divided into several 0.2 mm long sections. In each individual section, the partial arcs are cooled by large metal packages so that they tear off ("erased") quickly. At 500 Hz alternating voltage, this enables approx. 1000 sparks per second (one charge per half-wave), compared to only around 30 sparks with the pop-spark transmitter, which is noticeable by a "pleasant" buzzing sound on the receiving side, which is in contrast to the "creaking" of the Easily distinguish pop-spark transmissions from atmospheric disturbances. This is why this type of transmitter was also called sound spark transmitter .
Since the sparks break off after a few microseconds, the power supply is not damaged, although it is repeatedly short-circuited. Their current is limited by the self-inductance and the high frequency is kept away by choke coils. The resonance circuits of Tesla transformers are often operated with quenching spark gaps.
In 1908 the Berliner Gesellschaft für wireless Telegraphie mbH, System Telefunken, introduced this type of transmitter. Extinguishing spark and pop spark transmitters generate damped vibrations as Morse code signals that could be heard with very simple detector receivers . For the transmission of speech and music, however, only constant (undamped) vibrations can be used, which are modulated accordingly, which requires other vibration generators. The subsequently developed arc transmitters , machine transmitters and then the transmitter systems with electron tubes were used for modulated transmission of voice and music signals .
See also
Web links
- Telefunken 1.5 TK extinguishing spark transmitter
- Extinguishing spark transmitter TK05 from Telefunken
swell
- ^ Hanns Günther : Wave telegraphy. A radio technical internship. Franckh'sche Verlagshandlung, Stuttgart 1921, p. 64.
- ^ Franz Fuchs: Outline of the spark telegraphy in a commonly understood representation. 12th revised edition. R. Oldenbourg, Munich et al. 1922.