Circuit of stereo FM transmitter Hi-Fi with IC BA1404 with power stage

With this circuit you will be able to mount a mini stereo FM station and broadcast to your entire home, a simple way to have an audio link wireless with ease. With the FM transmitter BA1404 Hifi Stereo you can stream your music from your iPod MP3, satellite receiver, computer, DVD player, Mobile Phone, MP4 player and MP3 and other audio source directly to an FM receiver with crystal clear sound.

Schematic of the FM stereo transmitter BA1404

Schematic of the FM stereo transmitter BA1404This is the diagram of the transmitter, the connectors CN1 and CN2 are stereo audio inputs of the trimpot (pots can be added) are for the volume adjustment capacitor + resistor (R1 / C4 and C11 / R2) form the pre-emphasis filter in the case of Brazil is 75μS.

The crystal ensures 38KHz stereo broadcast, in case you do not find this component to the assembly of your circuit, you will have a mono high-quality transmission, the MPX signal (with 2 audio channels multiplexed), leave the pin 14 and join with the 19kHz pilot signal (pin 13) and return to ci on pin 12 and will take the stage high-frequency oscillator formed on pins 9 and 10, the coil of 3.5 turns of the type found in FM radios in parallel with the 10pF capacitor C13 will be responsible for the fluctuation in the FM band.

The following high-frequency signal of the transistor T1 pin 7 to ensure a greater distance n transmission, the antenna coupling capacitor C9 which may be a telescopic or a piece of stiff wire.

The power supply should be a battery 9Volts preferably rechargeable 9-volt feed to the power transistor, as BA for the integrated circuit 1404 is required only 3 volts or it can burn. then 3 1N4148 diodes are used as a reference voltage of 2.1 volts in this source.

When assembling this circuit, make sure all components are positioned in the correct place and then connect the battery, then connect an audio source such as an MP4 and a nearby FM receiver, adjust the coil, using a “little key “plastic or wood, until you hear the signal on the radio. If you can not try to set other values ​​for C13, and without then redo the settings.

Suggested PCB mounting stereo FM transmitter with integrated BA 1404 and crystal 38KHZ

Suggested PCB mounting stereo FM transmitter with integrated BA 1404 and crystal 38KHZSide of the copper

Suggested PCB mounting stereo FM transmitter with integrated BA 1404 and crystal 38KHZComponent side

Silk-screen components

List of material for assembly of the FM transmitter with BA1404

Resistors 1/8 Watt 5%
R1, R247K – Yellow, Violet, Orange, Gold
R3, R7270 – Red, Violet, Brown, Gold
R410K – Brown, Black, Orange, Gold
R54.7K – Yellow, Violet, Red, Gold
R6150K – Brown, Green, Yellow, Gold
R8, R922K – Red, Red, Orange, Gold
R10470 – Yellow, Violet, Brown, Gold
C1, C5, C10, C1210µF/16V – Polarized Electrolytic Capacitor
C2,C4, C7, C9, C11, C15, C171nF – 25V Ceramic Capacitor
C3, C6, C8, C13, C1410pF – 25V Ceramic Capacitor
C16470µF/16V – Polarized Electrolytic Capacitor
IC1BA1404 – FM stereo transmitter chip
T12SC2458 – RF Transistor
D1, D2, D31N4148 – Diode
L13.5 turns coil with adjustable core
P1, P21k – Trimpot – Volume Adjustment
ANTConnect telescopic antenna or piece of stiff wire
B19V battery
CN1Left audio connector
CN2Right audio connector
X138KHz quartz crystal
Solder, wire, printed circuit board, box, connectors, etc..

Download .BRD e .SCH Eagle files
Download .BRD e .SCH
Download PDF PCB files
Download PDF


  1. Hi, Toni!… I must thank you, the author of this article “Circuit Of Stereo FM transmitter Hi-Fi With IC BA1404”, for being kind and giving us the chance to get access to all the details of this project. I am Brazilian, too, and I’ve never found in the main Brazilian Electronics magazine such a solution for my need to broadcast indoorly the sound of my computer or the audio output signal of my DVD player.

    P.S. —-> Parabéns, Toni!… Continue assim… compartilhe seus projetos com os amantes da Eletrônica!…
    P.S. —-> Congratulations, Toni!… Keep going this way… share your projects with all Electronics lovers!…


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