This two chips AM radio receiver circuit is a tuned radio frequency (TRF) receiver of the standard AM (amplitude modulation) radio with broadcast frequencies at 550kHz-600kHz. This is a simple and easy to build AM radio circuit which only using two integrated circuits (IC). This circuit works with 9V voltage supply, you could use 9V standard battery to supply this AM radio circuit.

Parts list:

Two Chips AM Radio Receiver Circuit Works

The coils on the ferrite rod antenna (L1 and L2) and the variable capacitors (C2) make up a “tuned circuit”. It is a very selective filter. The frequency is selectable over a certain range by adjusting the tuning capacitor. The selectable signal is passed into IC1 (integrated circuit 484) where it is amplified and then detected. The 484 is a monolithic integral circuit equal to a ten transistor tuned radio frequency circuit. The resistor R2 and the capacitor C3 set the automatic gain control of IC1. The 484 requires a low voltage power supply (1.1 -1.8V). The voltage drop across diodes D1, D2, and resistor R4 is the correct supply voltage to IC1.

The output from a diode detector of the 484 is typically 40 – 60mV. This audio signal is too weak to drive a speaker directly. Capacitor C3 filters out the radio frequency component of the signal, leaving a clean audio signal.

The amount of gain control is varied by potentiometer R3, which also varies the audio level and consequently the volume. Capacitor C5 couples the audio signal from the volume control to the input of the audio amplifier. Our kit uses the standard design for the audio amplifier on the base of the integral circuit LM-386. To make the LM-386 a more versitile amplifier, two pins (1 and 8) are provided for gain control. With pins 1 and 8 open, the gain at 20, the capacitor will go up to 200. Capacitor C7 blocks the DC from the speaker while allowing the AC to pass.

Download the MK484 datasheet:

MK484 Datasheet

1 file(s) 429.98 KB

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This circuit available in kit module, you can purchase the kit at electronickits.com, or download the kit manual

Two Chips AM Radio Kit

1 file(s) 482.76 KB

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All general purpose transistors should work in this circuit, you can use BC549 transistors for this circuit.

The circuit use a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now replaced by the MK484. The design is simple and sensitivity and selectivity of the receiver are good.

All connections should be short, a veroboard or tagstrip layout are suitable. The tuning capacitor has fixed and moving plates. The moving plates should be connected to the “cold” end of the tank circuit, this is the base of Q1, and the fixed plates to the “hot end” of the coil, the junction of R1 and C1. If connections on the capacitor are reversed, then moving your hand near the capacitor will cause unwanted stability and oscillation.

AM Radio Receiver PCB Design:

The image below is an actual size (scale= 1:1) copy of the copper layer. Note that this is reverse so the veropins appear now on the left hand side at the top. Remember that this is the lower (solder) side, by viewing the top image you should be able to match up the positions of all components.

Please visit this page for detail explanation from author, schematic diagram and PCB layout of mini AM Rradio receiver circuit.