Dilshan R Jayakody’s Web Log

This tuner circuit is a quick prototype which I build to test the RDA5807M FM radio tuner IC. RDA5807M is a single-chip tuner IC with RDS and MPX decoder, and it equipped with I 2 C interface for control. The main reason to build this prototype is to understand the behavior of this chip. The prototype version of the RDA5807M receiver. At the time of this design, the website of the RDA microelectronics is not accessible from my location. Because of this reason, I download different versions of RDA5807M datasheets from the internet. While going-through those datasheets, I observed that it comes with limited information. Finally, I decided to build this receiver to verify some of those parameters and to review the RDS functionality of the chip. I build this receiver around ATmega16A MCU. I choose this MCU because I got a few of ATmega16A MCUs in my inventory and also due to the higher number of  I/O pin count. RDA5807M module. In this design, the volume is contro...

BA1404 is quiet famous FM stereo transmitter IC manufactured by ROHM Semiconductor . This 18pin chip contains FM stereo multiplexer, 19 kHz pilot tone generator and RF output stage with the oscillator. The FM transmitter in this article is also based on BA1404 and 78L33 voltage regulator. The FM transmitter in this article is specifically designed to transmit audio signals generated by PC/Laptop sound cards. To archive this goal, this transmitter is designed to drive using a 5V DC power source. Except for Q1 (38 kHz crystal) and L2 (oscillator inductor), this transmitter uses commonly available electronic components. 38 kHz crystal is vital to generate 19 kHz pilot tone and this crystal is available to purchase in several web stores. For L2, wind 3 turns of 22 S.W.G enameled copper wire on 5mm bobbin with an adjustable ferrite core .  This variable inductor is used to select the output frequency of the transmitter. To archive good quality output and frequency stability ...