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Stereo Digital FM Transmitter Circuit

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In this project, I have introduced a compact stereo digital FM transmitter circuit that operates in the frequency range of 87MHz to 108MHz. The frequency can be adjusted using two tactile push-buttons, with a 0.1MHz step size. The heart of the circuit is an ATMega8 microcontroller, which communicates with a 0.96-inch SPI OLED display and the KT0803L FM transmitter chip via an I2C interface. You can directly connect a microphone or an AUX cable to the board to broadcast your desired sound, such as playing a piece of music from your cellphone, computer, … etc. After conducting some tests, it was found that the circuit operates quite stable, and the received sound is clear and sharp.

To design the schematic and PCB, I used Altium Designer 23 and shared the project with my friends to get their feedback and updates using Altium-365. The fast component search engine (Octopart) allowed me to quickly consider components’ information and also generate the BOM. To get high-quality fabricated boards, I sent the Gerber files to PCBWay. I am confident that utilizing this circuit will be an enjoyable and fulfilling experience for you.



Schematic + PCB + Code: https://www.pcbway.com/blog/technology/Stereo_Digital_FM_Transmitter_Circuit_64d799f3.html

[1]: TLV1117-5.0: https://octopart.com/tlv1117-50cdcyr-texas+instruments-669252?r=sp

[2]: TLV1117-3.3: https://octopart.com/tlv1117-33idcyr-texas+instruments-669250?r=sp

[3]: MMBT304: https://octopart.com/mmbt3904lt1htsa1-infineon-21387159?r=sp

[4]: 2N7002: https://octopart.com/2n7002-7-f-diodes+inc.-335069?r=sp

[5]: KT0803L: http://radio-z.ucoz.lv/kt_0803/KT0803L_V1.3.pdf

[6]: ATmega8-AU: https://octopart.com/atmega8u2-au-microchip-77760652?r=sp


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