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 ...
This blog contains electronic, amateur radio, and embedded system projects, which I did during my free time. Unless otherwise noted, all the articles and projects described on this blog are based on my original designs.