|Radio and Electronics (DED Philippinen, 66 p.)|
|6. RECEPTION OF RADIOSIGNALS (AM - TYPE)|
This part of the radio has to deliver a certain amount of a rather constant dc-voltage.
But this power supply alone will not helps us, because we cannot connect it directly to the transducer for example. If we would do so, we would hear only one crack and nothing else, because the current flowing through the coil of the earphone or loudspeaker would be constant and therefore the diaphragm would be at rest afterwards (not producing any sound).
This means: the current flowing from the power supply to the transducer has to be controlled in a way that the diaphragm of the transducer will oscillate with the frequency of the AF-signal but whit a stronger amplitude than before.
This function: the control of the current from the supply to the transducer by the rythm of the AF-signal is done by a so called amplifier.