In the figure we have the way to obtain more power from an operational one using an exciter transistor. The transistor can be the BC548 for currents up to 100 mA or the BD135 for currents up to 500 mA. The power supply must be dual.

In the figure we have the way to obtain more power from an operational one using an exciter transistor. The transistor can be the BC548 for currents up to 100 mA or the BD135 for currents up to 500 mA. The power supply must be dual.