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This amplifier circuit is very cheap, because not a lot of components that are required, and the voltage or amperage required is also not too large, so the transformer or power supply is also quite cheap. IC which can be used in power amplifier circuit is the KA2201, LM820M, TBA820M, U820. This amplifier output of 2 W and 4 ohm impedance, which can be applied to the speaker with 4W power, on such small speakers in front of a PC. For the required minimum input voltage of 3 volts and a maximum of 16 volts, for the recommended voltage of 12 volts. Parts Resistor R1 = 100K R2 = 120R R3 = 100R R4 = 10R Capacitor C1 = 0.1uF C2 = 100uF C3 = 47uF C4 = 100uF C5 = 470uF C6 = 220pF C7 = 100nF IC U1 = KA2201 , LM820M, TBA820M, U820

Description. Here is the circuit diagram of a simple and low cost AM radio. The working of this radio circuit is straight forward. Inductor L1 and capacitor C1 forms the necessary tank circuit. Diode D1 performs the job of de-modulation. Transistor T1 is wired as a preamplifier whose output is further amplified by the IC LM386 to drive the head phone Z1. The 10K POT R3 can be used as a volume controller. Circuit diagram. Notes. The circuit can be powered from a 9V PP3 battery. Use a 100cm long metal wire as antenna. Experiment with the value of L1 for catching other bands. The circuit can be assembled on a Vero board.