This circuit, from a former publication of 1968 was originally designed for germanium transistors, but with the changes in the polarization resistors is adapted to work with silicon transistors. However, depending on the gain and applications, the reader can change the resistors of the base ground of the transistors, in order to obtain better performance. The circuit has low power consumption and can be powered by battery. 20 µF capacitors may be replaced by types 22 µF. The circuit consumption is very low and the powering is made by source, must have excellent filtration. Note the use of PNP transistors with inverted power source.
