radio transmitter

High Quality Stereo FM Transmitter circuit Diagram

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High quality Stereo FM Transmitter

If you want to transmit the music around the hause then you can make your own small radio station by making a project using this circuit. Make your own radio station with this circuit, and transmit the music around the house. You can transmit with the connecting of your mobile phone or another audio device and simply create a wireless link with you and a receiver in your area. The implementation is of this circuit easy. With the BA1404 HI-FI Stereo transmitter, you will be able to transmit MP3 music from your mp3 player, computer, TV / SAT receiver, and many other audio sources. In this ckt mic not use but directly audio input connects with the audio jack.

The Ba1404 ic is a good quality digital Fm transmitter.  BA1404 transmitter design that improves sound quality, has very good frequency stability, maximizes the transmitter’s range, and is fairly simple for everyone to build. We are happy to announce that this goal and expectations have been met and even exceeded. 

stereo fm transmitter circuit diagram

The transmitter can work from a single 1.5V cell battery and provide excellent crystal clear stereo sound. It can also be supplied from two 1.5V battery cells to provide the maximum range.

 Tunable RF coils are ideal for precise frequency tuning because their magnet wire is halfway embedded within the plastic, which minimizes frequency drifts. Regular air coils are not preferred for professional broadcasting because the coil expands and contracts with temperature changes. That’s the very reason why the variable coil was chosen as a substitution for an air coil and a variable capacitor.

One of the qualities of the BA1404 FM transmitter is excellent frequency stability. This is mainly due to the use of high quality 3.5 turn variable coil.

   There are several factors that account for improved sound quality and separation. The first reason is the use of 38 kHz crystal which provides rock-solid frequency for the stereo encoder. Another quality of the BA1404 transmitter is a crystal clear stereo sound and improved sound separation. Another reason is the use of two 1nF decoupling capacitors one for the BA1404 chip and another for 3.5 variable coil. These capacitors have to be as close as possible to a BA1404 chip and a variable coil because this will GREATLY improve the sound quality, sound separation, and even frequency stability as well. What they do is filter out the noise in the incoming DC voltage. If the noise enters the BA1404 chip stereo generator will include it in a transmitted sound affecting both the sound and multiplex signal that is responsible for the generation of the clear stereo signal. If that noise enters it will also be included in a generation of subcarrier frequency affecting the frequency stability. 

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For optimum transmission range, the length of the antenna should be 1/4 or 1/2 of the wavelength of the transmitted frequency. Use this simplified formula to determine the antenna length for 1/4 wavelength antenna type: (30000 / Transmitted Frequency) / 4 = Antenna Length (in cm)

  (30000 / 108MHz) / 4 = 70cm Antenna


 47k        2

 27k        2

 5.6k       1

 150k      1

 270Ω      1


1nf        6

10uf      4

220pf    1

10pf      5

Cristal 38khz  1

IC= BA 1404

L = enameled coil of copper 3 turn of 5 mm round

Frequently Asked Questions
What is the range of BA1404 Stereo FM Transmitter?
The range of the transmitter depends on many factors.
a) Length and type of the antenna (copper wire or pipe will radiate radio waves better than aluminum) 
b) Supplied voltage (3V Max power output)
c) Weather conditions (clear skies & no humid, greater distance)
d) Elevation above the ground (the higher the better) 
e) Line of sight (no buildings or trees, greater distance) 
f) Whether external amplifier is used 
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1 thought on “High Quality Stereo FM Transmitter circuit Diagram”

  1. my names are Amos Soko and would like thank you for helping me understand how bass boost for home thearter works and works very well.
    am requesting if you could assist me with the circuit diagram for active tone control that uses I.C. UPC4558 and be able to put out sound. Sir I tried the one that uses LM741 the performance was but the moment I used a line amp of transistor the sound loud characterised with heavy distortions .Sir help me to come with powerful pre amp yet using available components.
    Thank you Sir may the good Lord be with you.

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