This circuit is from Motorola's Linear Interface ICs from 1993. The MC1723 is the equivalent of the well-known 723. The transistor supports equivalents.
This circuit, from the 70's, can be assembled with a more modern FET like the BF245. The circuit is...
We found this telephone amplifier in a European publication from the 1980s. The transistor can be...
This is the factory setting (National Semiconductor) of the TDA2006 as an audio amplifier. The...