This is a circuit of good quality fm transmitter. There are many fm transmitter circuits I have made this year but I found this one good because it is frequency stable and also eat low power from battery there fore the battery last longer. It has a good range and ideal for broadcasting your music or voice around house and yard, the circuit takes power from 1.5 volt cell.
The cell can be of any size you can also use watch battery. Make the antenna wire 15 or 20 cm long. But if you want to increase transmitter range than make antenna wire 80cm long. Keep antenna wire vertical and use good quality fm receiver. Cheap quality fm radio will not receive signal from far away. After completing the circuit start your fm radio. Now take your fm transmitter 3 to 4 meter away from radio, tune your radio between 103 to 108 MHz and try to find out your fm transmitter signal, if you can't find your signal then leave radio remain on in any blank space between 103 to 108 MHz and slightly move your fm transmitter trimmer capacitor. Now stop when you find your signal in your radio.
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Part List
R1 = 5.6K Resistor
R2 = 10K Resistor
R3 = 39K Resistor
R4 = 100 OHMS
C1 = 0.47 UF Electrolytic Capacitor
C2 = 1N Ceramic Capacitor
C3 = 27 PF Ceramic Capacitor
C4 = 5 PF Ceramic Capacitor
C5 = 3 PF Ceramic Capacitor
C6 = 62 PF Ceramic Capacitor
C7 = 10N Ceramic Capacitor
Q1 = 2N2222A transistor
TR = 1 to 30 PF Trimmer Capacitor
L = 2 Turns of #24 Enamel Wire on 5 mm Former
