Simpler FM transmitter design
In FM transmitter designs you need to think hard about how the signal generated will be modulated by an external audio source. In simpler circuits, the configuration features themselves facilitate modulation, but in a more critical application we need an appropriate circuit. In this paper we describe a varicap modulator that can be used on many types of FM transmitters, regardless of their power. In frequency modulation the generated RF signal having a fixed frequency when pure (without modulation) varies this frequency between two fixed values, following the intensity of an external audio signal, as shown in figure 1. Frequency modulation (FM) The frequency range in which the signal varies is determined by the depth of the modulation which is converted back into a low frequency audio signal in a (discriminator) detector. This recovered audio signal can then be amplified and reproduced. In the simpler transmitters, when we apply the audio signal in an oscillator transisto...