This circuit diagram is quite simple and cheap…
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 = 100?F | 3V Tantalum bead Capacitors |
| C3,C4 = 470?F | 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 = 4700?F | 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 switc |
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.
