Here is a Simple Audio amplifier using a single IC AN7523. This amplifier gives an output power of 3 Watt in to an 8 Ohms loudspeaker on power supply of 9Volts.
An IC AN 7523 is a 9-pin legs IC. This IC 7523 is very common and available in a market easily and also is not expensive.
Circuit Description
The circuit shown is simple and straight forward. Only one semiconductor IC1 (AN7523) is used in this amplifier and few passive components like C1, C2, C3 and C4 and resistors R1 and R2.
Pin 1 of IC1 (AN7523) is connected to +9Volts power supply. An electrolytic capacitor C1 (470uF/25V) is connected to +9V and ground by facing positive terminal to +9V and negative terminal to ground.
Pin2 and 3 of IC1 (AN 7523) is connected to 8 ohms/3W speaker. Pin 3 is connected to ground.
Pin 5 is connected to +9V though a resistor R1 (47K). Resistor R2 ( 33K) and capacitor C3(10uF/25V) are connected between pin 5 and 7.Pin 7 is connected to ground. An electrolytic capacitor C4 (1uF/25V) is connected between pin 9 and pin 7 by facing positive terminal to pin 9 and negative terminal to ground.
Pin 6 of IC1 is and AF input terminal. A variable resistor VR1 (10K) connected to a negative electrolytic capacitor C2 (1uF/25V) and ground. A center pin of VR1 (10K) is connected to input terminal.
Construction and Adjustment
A PCB board given is suitable for building your amplifier. After making a PCB at first take an 18 pin IC and cut it in half. Now put the half of 18-pin IC on a PCB board and solder it. Do not insert an IC socket during soldering. Take a 2-pin IC socket and connect it to speaker terminal of amplifier. Take an AF socket and connect it to an AF input terminal o amplifier. Now take all the remaining components and place them and solder all of them.
Now take a power supply of 9Volts and connect it to power supply terminal of amplifier.
Take an 8 ohms/3W speaker and connect it to the speaker terminal of the amplifier. Rotate a VR1 and put it in middle terminal.
You’ll hear a humming sound coming out from a speaker while touching an input terminal with a small metal screwdriver.
Now your amplifier is working and ready for use.*
Parts List
IC1: AN 7523
Resistors
R1:47K
R2:33K
VR1:10K (preset)
Capacitor
C1: 470uF/25V
C2: 1uF/25V
C3:10uF/25V
C4:1uF/25V
Miscellaneous
9Volts battery, 18-pin IC sockets, 2-pin socket, 2-pin connector, wires, 8 ohms/3W speaker. t.c.
