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===The concept of a Transformer Microphone=== | ===The concept of a Transformer Microphone=== | ||
[[File:transformer_and_rectifier.gif|thumb|right|A Radio Signal Receiver]] | [[File:transformer_and_rectifier.gif|thumb|right|A Radio Signal Receiver [http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/amfmdet.html#c1 source]] ] | ||
To get rid of our big magnets, we build an electro magnet with the help a a sending coil that will build up a magnetic field. When the current though this sending coil changes, it will induce a magnetic field, that we can use to induce a current in the second (receiving) coil. Two coils that share their magnetic flux via the air are called an "air core transformer". Both coils will be printed on paper, but on different sheets, leaving a gap filled with air. If the sheets are close together the second coil induces more current and lesser when it is further away. It is important, that the currents change constantly, because only changing currents can induce magnetic fields. We will use a high frequency changing current (50Khz) on the sending coil, that we will receive on the other coil. When we change the distance between the coils, the actual amplitude (volume) of this high frequency tone increases or decreases. To get the actual volume information of this high frequency tone, we use the half wave rectifier. This circuit is commonly used in radio signal receivers, where the amplitude of the the frequency of a radio station is changing with the actual transmitted sound wave. This is called Amplitude Modulation (AM Radio). | To get rid of our big magnets, we build an electro magnet with the help a a sending coil that will build up a magnetic field. When the current though this sending coil changes, it will induce a magnetic field, that we can use to induce a current in the second (receiving) coil. Two coils that share their magnetic flux via the air are called an "air core transformer". Both coils will be printed on paper, but on different sheets, leaving a gap filled with air. If the sheets are close together the second coil induces more current and lesser when it is further away. It is important, that the currents change constantly, because only changing currents can induce magnetic fields. We will use a high frequency changing current (50Khz) on the sending coil, that we will receive on the other coil. When we change the distance between the coils, the actual amplitude (volume) of this high frequency tone increases or decreases. To get the actual volume information of this high frequency tone, we use the half wave rectifier. This circuit is commonly used in radio signal receivers, where the amplitude of the the frequency of a radio station is changing with the actual transmitted sound wave. This is called Amplitude Modulation (AM Radio). | ||