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

Download Datasheet

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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Components List:

The MK484 we use is a Japanese copy of the original ZN414. It contains an RF amplifier, active detector and automatic gain control (AGC to improve sensitivity) all in a 3-pin package. The input impedence is typically 4M ohm. It operates over a range of 150kHz to 3MHz. DC supply of 1.1V to 1.8V & 0.3mA current drain makes it ideal for battery operation. The output is typically 40 – 60 mV of audio signal. Optimal AGC is provided by R3 and C2 (see Figure 2). R3 (the AGC resistor) should be in the range 100R to 1.5K. A bandwidth of about 4kHz is achieved.

Download the MK484 datasheet:
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The MK484 is now a discontinued IC. It was made by New Japan Radio although it does not appear anywhere on their website(s). You may try to find the equivalent IC for MK484.

Download the complete explanation of this AM radio receiver circuit:
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Note: The kit for this circuit is available at kitsrus.com.