Magnetic detector

The magnetic detector was one of the first devices with which it was possible to receive wireless radio signals through headphones. Although not quite as sensitive as other detectors at that time, magnetic detectors are preferably used because of their reliability on ships.

History

When Guglielmo Marconi carried out experiments to 1902 transatlantic communications in the year, he noted that the coherer previously used for the reception of very weak signals are too insensitive and too unreliable and was looking for better systems.

Function

An endless belt made ​​of iron runs, similar to a tape, at the poles of permanent magnets and is magnetized by thereby. At the same time acts on the tape one of the high-frequency current from the receiving antenna, which, depending on its amplitude, stronger or weaker demagnetized it. Characterized the remaining magnetization is modulated with the amplitude of the RF signal. Then, the low-frequency band described above is magnetically guided past a Tonabnehmerwicklung whose output voltage is applied to a headphone, so that the modulation of the received signal is made ​​audible.

• Wireless technology
• Historical communication device