Image of FM Transmitter
Part List :
10 Mfd, .01 Mfd, .001Mfd, 2.2pf, 4pf, 5pf, 27pf, 68pf
Coil : 6-7 Turns using 26 SWG Wire
3.3K, 2.7K, 3.9K, 220 Ohms
Mic = Condenser Mic
Battery 3V with Container, Switch
The circuit uses only single Transistor but good voice quality. This Circuit is very simple and uses few components. Main part of the circuit is LC ( Coil Capacitor ) Tank circuit to produce RF at required Frequency band. A transistor is used to power the LC circuit. The resonant frequency for an LC tank circuit is f = 1/(2pi * sqrt(LC) )
At FM receiver Device, Radio waves(oscillating magnetic lines) produces current in Arial. Which is further amplified, Demodulated and feed to a Speaker.
Circuit Diagram of FM Transmitter
This Video explains how Radio waves are produced.
This video explains how LC circuit works.
As you see energy decreases in a RC circuit so transistor is used to give power at same frequency.