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18W Audio Amplifier circuit diagram

2015-01-03 16:31  
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This circuit diagram is quite simple and cheap…

18W Audio Amplifier circuit

Amplifier parts:

P1 =22KLog.Potentiometer (Dual-gang for stereo)
R1 = 1K1/4W Resistor
R2 = 4K71/4W Resistor
R3 = 100R1/4W Resistor
R4 =4K71/4W Resistor
R5 = 82K1/4W Resistor
R6 = 10R1/2W Resistor
R7 = R224W Resistor (wirewound)
R8 = 1K1/2W Trimmer Cermet (optional)
C1 =470nF63V Polyester Capacitor
C2,C5 = 100?F3V Tantalum bead Capacitors
C3,C4 = 470?F25V Electrolytic Capacitors
C6 = 100nF63V Polyester Capacitor
D1= 1N414875V 150mA Diode
IC1= TLE2141CLow noise,high voltage,high slew-rate Op-amp
Q1 = BC18250V 100mA NPN Transistor
Q2 = BC21250V 100mA PNP Transistor
Q3 = TIP42A60V 6A PNP Transistor
Q4 = TIP41A60V 6A NPN Transistor
J1RCA audio input socket

Power supply parts:

R9= 2K21/4W Resistor
C7,C8 = 4700?F25V Electrolytic Capacitors
D2100V 4A Diode bridge
D35mm. Red LED
T1220V Primary, 15 15V Secondary 50VA Mains transformer
PL1Male Mains plug
SW1SPST Mains switc


Can be directly connected to CD players, tuners and tape recorders.Don’t exceed 23 23V supply.Q3 and Q4 must be mounted on heatsink.D1 must be in thermal contact with Q1.Quiescent current (best measured with an Avo-meter in series with Q3 Emitter) is not critical.Adjust R3 to read a current between 20 to 30 mA with no input signal.To facilitate current setting add R8 (optional).A correct grounding is very important to eliminate hum and ground loops. Connect in the same point the ground sides of J1, P1, C2, C3 &C4. Connect C6 at the output ground.Then connect separately the input and output grounds at the power supply ground. 


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