This very low power amplifier is designed by Amperex for hearing aids. It is based on TAA370 which is not an integrated circuit that can be found today.
This circuit of a documentation on very old oscilloscopes uses the first commercial transistor of...
This circuit was found in an application note of the LTC1164 from Linear Technology of the 1990s....
September 2017 - Can be purchased from Mouser Electronics Triacs with 20 A and 30 A currents...