Build Your 88-108MHz 4W FM Transmitter Circuit

TECHNICAL SPECIFICATIONS:

A stable DC voltage supply is provided: Vcc = 12~16V
The emitted frequency ranges from 88~108MHz.
Power consumption varies between 100~400mA.

Circuit Diagram:

Detailed Components:

[h3]Integrated Circuits[/h3] Two 2N2219 integrated circuits are utilized in this circuit. These are small-signal transistors, commonly employed for amplification and switching applications due to their low voltage and current requirements. They are typically used as switches or amplifiers in low-power electronic circuits.

Component List:

Resistors are rated at 1/4W.
R1, R2 – 10 kΩ
R3 – 47 Ω
C1, C2 – 1 nF
C3 – 4.7 µF / 16V
C4, C7, C8 – 0 ~ 45 pF trimmer capacitors
C5, C6 – 10 pF
C9 – 100 nF
L1 – 4 turns, 7mm diameter *
L3 – 3 turns, 7mm diameter *
L4 – 5 turns, 7mm diameter *
L2 – RFC (resistance 1 MOhm with wrapped around her inductor of enough coils from fine isolated wire. Scratch of utmost inductor and you stick in utmost the resistance making thus a parallel L-r circuit.)
T1, T2 – 2N2219
ANT – Simple dipole l/2.
MIC IN – Microphone dynamic or other type. (It can also connected to a cassette player unit)

PCB:

Ensure the screen resolution is set to 1280 by 1024 before printing with Microsoft Paint to achieve the correct scale.

Regulations:

The frequency is regulated with C4.
C7 and C8 are utilized to adjust the aerial resistance (practically, these are adjusted to ensure clear voice reception in the radio as you improve audio quality).

Notes:

The T2 is intended for refrigerator use.

author: Kyriakos Kontakos, kkontak@hotmail.com
circuit from http://www.electronics-lab.com/