So, a 22pF trimmer is a good choice to be used as VC in the circuit. You should be able to change the capacitance of the variable capacitor from a couple of picofarads to about 20 pF. The information signal used in the transmitter to perform the modulation is extracted on resistor R1 and fed to the audio amplifier over a 220nF coupling capacitor (C1). That is, it has to be tuned between 88 and 108 MHz. Trimmer VC sets the resonance frequency of this oscillator to the frequency of the transmitting station that we wish to listen to. Transistor BF495 (T2), together with a 10k resistor (R1), coil L, 22pF variable capacitor (VC), and internal capacitances of transistor BF494 (T1), comprises the Colpitts oscillator. Here’s a simple FM receiver circuit with minimum components for local FM reception. Presented below is an FM Radio Circuit Diagram along with its full explanation. This allows a much larger range of frequencies to be transferred in FM and thus the quality of FM transmission is significantly higher than that of AM transmission. The maximum audio frequency transmitted in FM is 15 kHz as compared to 4.5 kHz in AM. The FM radio transmitter has a 200kHz wide channel. This bandwidth range is marked as FM on the band scales of radio receivers, and the devices that are able to receive such signals are called FM receivers. FM Frequency Rangesįrequency modulation is used in a radio broadcast in the 88-108MHz VHF frequency band. We have also designed a simple stereo amplifier circuit. It is also used in telemetry, radar, seismic prospecting, and monitoring newborns for seizures via EEG, two-way radio communication systems, music synthesis, magnetic tape-recording systems, and some video-transmission systems.Īn advantage of frequency modulation is that it has a larger signal-to-noise ratio and therefore rejects radio frequency interference better than an equal power amplitude modulation (AM) signal. Frequency modulation is widely used for FM radio broadcasting. Of the radio waves, FM is the most popular one.
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