Simple FM Radio Receiver Using KA 2101

This intermediate-level project implements an analog FM radio receiver designed to capture standard 88-108 MHz broadcast signals. The signal capture begins at the front end with the BF494 RF transistor, which handles initial radio frequency amplification and helps tune into the desired frequency band alongside the various passive capacitors (such as the 47pF, 68pF, 33pF, and 0.04uF values) and tuning elements. The core demodulation and intermediate processing rely on the 14-pin KA2101 integrated circuit, seated securely in an IC socket on the 5cm x 7.5cm Vero board. The KA2101 works in conjunction with components like the 5.5 MHz IFT coils or 5.5 MHz ceramic filters to isolate the intermediate frequency and extract the audio signal from the carrier wave. Because the KA2101 handles signal processing rather than heavy audio driving, the extracted audio output is routed to an external audio amplifier section—built around a TBA 810 or TBA 820 IC and speaker—to drive audible sound waves into the room. The entire analog system is powered by a standard 9V battery and clip, making it a completely self-contained analog receiver circuit built without any programmable microcontrollers or software.