We found this circuit in an Electronic Engineering of the 90s. The circuit can be implemented with any logic and next to the diagram the truth table for the indications is given.
This two stages amplifier is used with high impedance earphones. The transistors are very old...
August 2017 - The new N-channel MOSFETs from Vishay's TrenchFET Gen IV family can now be purchased from...
This circuit is from a documentation on the MC1539 from Motorola and may, however, be implemented...