This document describes the design and working of a wireless FM transmitter circuit that can transmit frequency modulated signals within the range of 88 MHz to 108 MHz using low power over a short range of 20 to 30 meters. The circuit uses components like transistors, capacitors, resistors, and wire to build an inductor and antenna. When an audio signal is input, it is mixed with the FM frequency for transmission. The circuit allows for wireless audio signal transmission that can be used in various places and institutions.

1. A transmitter is an electronic device
which produces radio waves with the
help of an antenna.A FM transmitter is
a low-power (FM radio transmitter) that
broadcasts a signal from a portable
audio device to a standard FM radio.
Objective:
To build a wireless FM transmitter
which can transmit frequency modulated
signal within the frequency range 88
MHz to 108 MHz using low power in a
short range approximately 20 to 30
meter.
Introduction:

2. List of equipment:
Transistor 2N3904,
Capacitor o.047 μF,10 μF,O.o1μF,
5.6pF, 5-20 pF(trimmer capacitor)
Resistor 27kΩ(2 pics), 4.7kΩ,270Ω
19-20 AWG wire (for inductor &
antena)
Voice input jack
9V battery
Circuit Diagram:

3. A Project
on
Communication
Project Tittle: FM transmitter
Submitted To,
Md. Mamunur Rahaman
Lecturer
Department of EEE
World University of Bangladesh
Submitted By,
Md Kawsar Ahmed Shamim(2859)
Shah Md Nure Nabi Isdani Apu(2861)
Mijanur Rahaman(2706)

4. Working principle:
When we will input the voice,it will
receive the audio signal is mixed with
range FM frequency to transmit.The audio
input is just bring to the FM radio
receiver tuned provide the radio only.
In Figure this circuit has very little
equipment,audio jack through it voice
will be input.The circuit is supplied to
the resistor 27K positive in the leg
microphone,and it is way out of with the
audio signal,through the coupling
capacitor to pin B of Q1, Which Q1 also
acts as both the radio frequency
generator and the audio mixer on the
Radio frequency is generated. and at B
pin of the Q1 have the resistor R2 –
27K with R3 – 4.7K are divider circuit,
Divided a number of voltage to the bias
for Q1. and the capacitor C2-0.01uF is
connected to ground for bypass the high
frequency, At C pin of the Q1 is
connected pass the coil to the positive
voltage.Using copper wire No. 19-20 AWG,
wrapped around the air core diameter of
7 mm and stretch to 15mm and connect it
to the trimmer capacitor. And pin C of
Q1 is connected to the antena.

5. This circuit can be used at any place to
transmit audio signals using FM transmission,
especially at institutions and organizations.
Here we made FM transmitter using lot’s of
electronic equipment.There is low or high of
noise oscillator function in this circuit,
equipment with high quality or not, The
soldering is good or not,for it’s difficult to
operate and determine the range.
Application:
Discussion: