|
|
Circuits > Audio > 18W Audio Amplifier
18W Audio Amplifier
|
-- High Quality very simple unit
|
|
-- No need for a preamplifier
|
Circuit diagram:
Amplifier parts:
|
P1 = 22K
|
Log.Potentiometer (Dual-gang for stereo)
|
|
R1 = 1K
|
1/4W Resistor
|
|
R2 = 4K7
|
1/4W Resistor
|
|
R3 = 100R
|
1/4W Resistor
|
|
R4 = 4K7
|
1/4W Resistor
|
|
R5 = 82K
|
1/4W Resistor
|
|
R6 = 10R
|
1/2W Resistor
|
|
R7 = R22
|
4W Resistor (wirewound)
|
|
R8 = 1K
|
1/2W Trimmer Cermet (optional)
|
|
|
|
|
C1 = 470nF
|
63V Polyester Capacitor
|
|
C2,C5 = 100µF
|
3V Tantalum bead Capacitors
|
|
C3,C4 = 470µF
|
25V Electrolytic Capacitors
|
|
C6 = 100nF
|
63V Polyester Capacitor
|
|
|
|
|
D1 = 1N4148
|
75V 150mA Diode
|
|
|
|
|
IC1 = TLE2141C
|
Low noise,high voltage,high slew-rate Op-amp
|
|
|
|
|
Q1 = BC182
|
50V 100mA NPN Transistor
|
|
Q2 = BC212
|
50V 100mA PNP Transistor
|
|
Q3 = TIP42A
|
60V 6A PNP Transistor
|
|
Q4 = TIP41A
|
60V 6A NPN Transistor
|
|
|
|
|
J1
|
RCA audio input socket
|
Power supply parts:
|
R9 = 2K2
|
1/4W Resistor
|
|
|
|
|
C7,C8 = 4700µF
|
25V Electrolytic Capacitors
|
|
|
|
|
D2
|
100V 4A Diode bridge
|
|
D3
|
5mm. Red LED
|
|
|
|
|
T1
|
220V Primary, 15 + 15V Secondary 50VA Mains transformer
|
|
|
|
|
PL1
|
Male Mains plug
|
|
|
|
|
SW1
|
SPST Mains switch
|
Notes:
-
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.
Technical data:
Output power: 18 Watt RMS @ 8 Ohm (1KHz sinewave)
Sensitivity: 150mV input for 18W output
Frequency response: 30Hz to 20KHz -1dB
Total harmonic distortion @ 1KHz: 0.1W 0.02% 1W 0.01%
5W 0.01% 10W 0.03%
Total harmonic distortion @10KHz: 0.1W 0.04% 1W 0.05%
5W 0.06% 10W 0.15%
Unconditionally stable on capacitive loads
Title: 18W Audio Amplifier
Source: www.redcircuits.com
Published on: 2005-02-01
Reads: 1117
Print version: 
Circuits > Audio > 18W Audio Amplifier |
|
