This circuit is an improvement of the previous one, with the use of two transistors produces a higher power audio output. The original circuit is from a Radio Electronics 1990. The magazine is no more published, but the circuit can be assembled easily with the modernizations we did. The transistors may be the BD548 and BD558 for power 9 V and BD135 and BD136 in output or other complementary pair of power supply to 12 V. The power supply must be symmetrical 9 + 9 V. The source must have excellent filtering and the input impedance is high. As load can be used an 8-ohm speaker.
