9012, 9013 OTL discrete component power amplifier circuit diagram

Q1 is the excitation amplifier tube, which provides sufficient push signal to the power amplifier output stage; R1 and RP2 are the bias resistors of Q1; R3, D1, and RP3 are connected in series on the Q1 collector circuit to provide bias for Q3 and make it static is in a micro-conduction state to eliminate crossover distortion; C3 is a damping capacitor, used to eliminate possible self-excitation in the circuit; Q2 and Q3 are complementary symmetrical push-pull power amplifier tubes, forming a power amplifier output stage; C2, R4 Form a "bootstrap circuit", R4 is the current limiting resistor.

Circuit debugging

Connect the 3-6V DC power supply, adjust RP2 so that the midpoint voltage of Q2 and Q3 is 1/2 the power supply voltage; adjust RP3 so that the quiescent current of the power amplifier output stage is 5-8mA; repeatedly adjust RP2 and RP3 to make the two parameters equal. reach the above value.