30W Class AB power amplifier circuit diagram using power transistor. Set the above amplifier up by adjust the variable resistor R1 to maximum and R12 to zero. After this set up is done, the activate / turn on the amplifier. Adjust the R1 so that the measured output offset is between 30 and 100mV. Once set, adjust the R12 slowly to achieve a quiesc
ent current of around 120mA. Keep checking the quiescent current as the amplifier heats up as it might change due to voltage drop changes in the output devices because of the heat. The heatsinks should be 0. 6K/W or less for two amplifiers.